Reaction Injection Moulding of Syndiotactic Polystyrene: The Effect of Reaction Parameters on Monomer Conversion and Polymer Properties

Colin Li Pi Shan

A ehesis subrnitted to the Department oÇChemistry in conformity with the

requirements for the degree of Mas ter of Science (Engineering)

Queen's University

Kingston, Ontario, Canada

September 1997

copyright O Colin Li Pi Shan, 1997 National Library Bibliothèque nationale I*I of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. rue Wellington OttawON K1AON4 Ottawa ON K1A ON4 Canada Canada

The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sel1 reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la fome de microfiche/^ de reproduction sur papier ou sur format électronique.

The author retains ownership of the L'auteur consenre la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fkom it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Abstract

The primyy objective of this research wu to investigate the narure of the conversion limitation in the developrnent of a novel syndionctic polystyrene (sPS) rel-ctioii injection mouldiiig

@Ili) pmcess. By vqing the reaction p*Lu;uIieteeof the estent of mising, reaction rime wd mould wall tempenture, the effects on the monorner conversion ünd polymer properties were determinrd.

Cdiztng a two component medlocene cataiyst system comprised of Cp*TiuMe~and B(Cfi F-),3, styrene monomer \vas polmerized in bulk in a specially constructed RIM app;irJtus to produce syndior~ctic polysryrene. Ir \vas obsemed diat the reÿction wÿs highly esothecmic md that hi& conversions to hi$? syndiotactic polymer occurred.

It w:is found tliat r-ing the mould w;Jl tempenture Ii:id the largest effecr on tlic polynerization. .At the lower mould tempemures, increases ùi the conversion were fouiid. At Liotli the highest and lowest rempenture estrernes snidied, it wvs discovered that die polymer proprrries detecior~ted. In studying different reaction times, it was found t1i:ir the catalysr activity ç:ui I)c sustaîned for longer duntion to increase the conversion while m~iiitaiiiilgthe polyner propertics.

.it short reaction times the polyrnerizarion occurs quite mpidly -and hi& convenioiis cmbe diievcd within minutes. Vsqing the estent of misuig had little to rio effect on die coiiversion and polymrr properries.

In dl die conditions snidied to reduce an- difhsion or temperature limirritions, a limitirig conversion w;is sdl reached. Investigations into the cystdlirie iiamre of the polymer revealed thac the coiivenion limitation of the polymerïzation may be due to the enrrapmenr of styrene monorner widiin die c~srailùieregioiis of sPS. This entrapmenr is hypodiesized to occur via a styrene-sPS rnolecuhr cornples which is related to the hel ical conformations of s yiidio tactic pol ystyrene. Acknowledgements

1 would like to thank Dr. Vi.E. Baker for his guidance and supervision, riot onlv in the

aspects of the project but as educator in the aJLiing of Engmeering Cliernists. 1 dso esrend my

thanks CO both Dr. M.F. Cunningham and Dr. K.E. Russell whose researcli esperieiice ïiid

suggestions were induable. -Yso, 1 musr acknowledge Dr. MC. Baird aid his Iab goup fr)r

providing the srarting materials and technicd expertise for the cntalysc sydieses.

My thmks, dso spreads out to the members of the Baker L;lb who suppocted my

frustrarions ÿnd triumphs while making the esperience enjoyable. Specid diÿnks so to D. (Iuk :uid

S. Hojabr for helpfLl discussions and to Dr. T. Liu for his previous esperieiice -and assistance witli

the ariaiyticd TG.% work.

Lastly, 1 would like to express my sincere gr~titudeco rny Eimily hr alwïdys supporurig my endeavours. -4 special tvord is dso bestowed ro my friends, for the friendships 1 have treasured at

Queen's. Table Of Contents

Absuact Acknowledgements Table of Contents List of Figures List of Tables List of Symbols

1.0. Introduction

Z.I. Syndiotaak Polysîyrene 1.1.1 Background to sPS 1.1.1.1 Properties of Polystyrene 1.1.1.2 Structud Polyrnorphism of sPS 1.1.2 Syndiospedic Polymerization O f Styrene 1.1.2.1 Cadysa and Mechanisms 1.1.2.2 Effect O t Po1ymeriz;ition Conditions on Catalyst ;ictivity ;ind Material Properties 1.1 .î.3 High Conversion Styrene Polymerizations 1.2 Con ven ti'onai Sryrene PoI'erÙatio~ 1.2.1 Thermÿl and Bulk Polymerization of Styrenr 1.2.2 Difhsion ControIIed Phenomena 3.3 MM Processing 1.3.1 Introduction to RIhI 1.3.2 Wh1 Processing Requirements 1.3.3 Previous studies of RIhl Processing of sPS 1.4 Auns ofdiis Study

2.0 Expetimental

2.2 Mateds 2.2 Metdocene Cacllyst Synthesis 2.2.1 Prepmtion O t Cp0Tihfe,Catdyst 2.2.2 Prepmtion of B(C,Fd, Cocatdyst

2.3 Reaction Injecrion MouidUIg PolymerUations 2.3.1 RliLl hlising =\pparatus 2.3.2 Rihl Technique 2.3.3 Temperature Monito~g 2.3.4 Esperimennl Studies 2.3.4.1 Prepolymerization of Styrene by Borne Coçaralys t 2.3.1.2 Benchmark Control Study 2.3.4.3 M.sing Study 2.3.4.4 Reaction Time Study 2.3.4.5 .\lould \Xd Tempemture Study 2.3.5 Rcsidual LIonomcr Loss/(:onversion Estimate Table of Contents Cont'd.

2.3.5.1 \Txuum Oven drying 2.3.5.2 Thermogravime tic rùidilysis

2.4 Charactenkarion of PS Polymers 2.4.1 Deterrnination of sPS/aPS Frxtions 2.4.2 Product Identification and Txticity Analysis 2.4.3 Determination of ThedProperties 2.4.4 Deterrnination of Molenilar Weight 2.4.5 Estimaaon ofsPS Crystdlinity and Identification of Crysnlline Forms

3.0 Results and Discussion

3.1. EstUnating the Monomer Conversion ofBulX-Pof'enZed RIM Samples 3.2 Control Smdy ofRIM Polperizations 3.2.1 Benchmark Reproducibility 3.2.2 Characteristics of RIhl Polystyrene 3.3 Effect ofilhkihg on the MM Poiymerization 3.3.1 Effect of Mising on Conversion 3.3.2 Eifect of hllxing on Material Properties 3.1 Effect of Theon the RIM Polymerization 3.4.1 Ef'fect of Retiction Tirne on Conversion 3.4.2 Effect of Reaction Tirne on Marerixi Pro perties 3.5 Effecrof Mouid Temperature on the MM Polymnkatio~ 3-51 Effect of Mould \Vail Temperature on Conversion 3.5.2 Effect of Mould W'dI Temperature on Materid Properties 3.6 Conversion Limirations of the Polymenkation

4.0 Conclusions

5.0 Recommendations and Future Work

References Table of Contents Cont'd.

Appendices and Curriculum Vitae

Typicd TGA Therrnogm of sPS RIM Smple Randomized Experimentd Run List Borane Prepolymerization Smdy =HN&fR ofsPS 'H YhIR ofaPS 13cUiR of sPS NMR of aPS DSC Thermal Trace ofsPS Sample lilxing Study G: Reacuon Time Study H: Mould \Val1 Temperature S~dy 1: Crysnllinity Estimates of sPS Samples

Curriculum Vitae List of Figures

Fig. 1.1: Strucninl configurations of polysryrene Fig. 1.2.1: sPS zigzag and helical represenntions Fig. 1.2.2: Methods of obnining sPS ~xystdlineforms Fig. 1.2.3: Structurai representations of sPS-roluene molecular complrs Fig. 1.2.4: Representation of the entrapment of benzene molecules within sPS moie~vles Fig. 1.3.1: MeMi-coordinated insertion mechanism of styrene Fig. 1.3.7: P-hydrogen elimination reaction in styrene polymerizations Fig. lA.1: Styrene polymerimtion canlyzed by Cp'TiiLIe,/,LLiO Fig. 1-42 EFfect ofstyrene concentration on the monomer conversion Fig. 1.4.3: Effeect of increasing polymerizi~tiontime on the monomer conversion Fig. 1.4.4: EEeçt of increasing temperature on the monomer conversion Fig. 1.4.5: Variation of syndiotactic yield and melting point of sPS versus pol y merization temperature Fig. L.5.1: Thermal Initiation O ï Styrene Fig. 1.5.2: Chain Growth Propagation of Styrenr Fig. 1.6: Effect of Diffusion Controlled Temination Fig. 1.7: Schematic of a RIM process

Fig.2.1: RIM hlishead Schematic Fig 2.2: RI,\;[ :lppariltus Setup Fig 23: Flowchart of the Ch~mcrerizationof RIM S:unples Fig 2.4: ' H SMR of mehine and methylene C region of polystyrenes Fig 2.5: 13 C SMR of phenyl C region of polystyrenes Fig 2.6: Eupanded inkued specaa of sPS smples in three differerent regions Fig 2.7: FTIR IR specn of sPS dis tinguis hing a and P çrystalline toms Fig 2.8: FTIR IR specm ot'sPS distinguishing 6 and y crystdline forms

Fig. 3.1: Typicd sPS RNpolymerization reaction temperature pro file Fig. 3.3- 1: Effect of mixing method on the monorner conversion Fig 3.3.2: Effect of the mking method on the sPS fraction Fig. 3.4.1: EfFect of reaction time on the monomer conversion List Of Figures Cont'd.

Fig. 3.4.2: Effect of reaction time on the sPS Enchon Fig. 3.4.3: Effect of reaction time on sPS ~vt.avg. molecular weight Fig. 3.4.4: Effect of reaction time on sPS num. iivg. rnolecular weight Fig. 3.5.1: 60 OC mould wdl temperature pro tile Fig. 3.5.2: 110 OC mould wdvall tempenture profile Fig. 3.5.3: O OC mould wdl temperature profile Fig. 3.5.4: -20 OCmould wdl tempenture profile Fi. 3.5: Effect oE mould 41temperature on the monomer conversion Fig. 3.5.6: Effect of mould dltemperature on the sPS haion Fig. 3.5.7: Effect of mould w;dI tempenture on the sPS lvt. avg. moleculi~weighr Fig. 3.6.1: FTIR - Identification of sPS helicd forms in the 400-650 cm ' region Fig. 3.6.2: FTIR - Identification oisPS helicd forms in the 660-940 cm.' regton Fig. 3.6.3: FTIR - Suggested presence of zig-mg forms in the 1 100-1400 cm ' region Fig. 3.6.4 FTIR - Distinguishing the S-form from the y-form in rhr 940-1020 cm ' regton Fig 3.6.5: FTIR - Identitication of the morphous fom in the 820-860 cm ' region List Of Tables

Table 1.0: DCP RIM Formulation 29 Table 3.1: Cornparison of Conversion Estimates for Vacuum Oven Drying and TG.\ 53 Wt. LOSS Table 3.2: sPS RIhf Benchmark Consenion Reproducibility 56 Table 3.3: sPS RIM Benchmark Polymer Properties 37 -! Table 3.4: Mould \Val1 Average Reaction Tempemtures / 2 Table 3.5: DSC Crysnllinity Estimates of sPS Samples 81 Table 3.6: Predicted Conversions due to Monomer Entmpmenr by sPS Crysrals s 1 List of Syrnbols aPS - anctic polysqrene .US - poIy(acqloniuile-bundiene-sqrene) .UBX - azoisobutyronitnle BM - benchmark Cp - qclopentadienyl Cp' - pei~omediylqclopen~dienyl d - chamber diameter (cm) DCP - dicyclopemadiene DOF - degree of freedorn DSC - differentid scanning caloturieuy ESR - elecuon spin resonance spectroscopy FIIR - Fourier uansfom infmed specuoscopy GPC - gel pemeation chromaropphy HTGPC - high temperature gel permeauon chrom;itognphy iPS - isotactic polystyrene HIPS - tiigh impact polystyrene LDhl - large diametei rnising LLAO - methylduminosane hlEK - methyl ediyl ketone SMR - nucle-ar mgnetic resonance spectroscopy SSlI - no sratic misiiig PDCP - polydiqcloperitadiene PE - polyethyiene PET - polyethyiene terephdialate PP - polypropyleric PS - polyscyrene Q - tlowr~tein cm3/s Re - Reynolds number RIM - re.~ctioninjection rnoulding RRIM - reiriforced reaction injection rnoulding sPS - syiidior,icric polysryrene S.<\ - poly(syrene-acryioni trile) SE\ [ - scanning electron microscopy SINC - solvent induced cqsdlization TCB - trichlorobenzene Tg - ghss tmisition TG .A - thermogr~vimetricmal ysis TI,\.[- thennoplastic injection rnoulding Thl\ - trünethylduminum - test cube mising Z-S - Ziegler-Sam cadysts p - zigzag plaiiÿr (onhorhombic) crysdline form ofsPS 6 - Iielicd crysrdine form of sPS y - Iielicd crysdine form ofsPS q - riscosity (poise) Chapter 1 1.0 Introduction

1.1 Syndioractic Polystyrene (sPS)

1S.l Background to sPS

1.1.1.1 Properties of Polystyrene

The monomeric precursor, styrene, is the simplest mmtic compound haviiy :ui wamrated side-ch&. Uniquely, the polynerization of styrene proceeds readily, using dI mediods of poly-nerization, under the influence of heat alone md/or m initiator. It is one of die &w monomers thar cm be polynerized by the four disthicr mectiiuiisms of free r~did,the ioiiic mechanisms of mionic and cationic ünd coordination polymerizatioii. 50 yecirs ilgo, Dow Chttmtcd

\vas die first cornpany to cornmercialize polysvrene successtl1ly.l Tr~dïy,polys-rene PS) is ;L wmmodity polmer aiid maiy different grades are produced by a wriety of differeiit processer ibr :L varie- of applications. r\ very large business hÿs developed for polystyeiie aid its copolymers suc11 u mbber-modified polystyene (HIPS), ac-loiiitrile-sqreiie çopolymrrs (S.AS) and rubber modified licqlonitrile-scyrerie copol ymers (.%Bq.

nie most distinguishitig characreristic of generai purpose polystyene is diiit ir is :ui amorphous, bntrie, glas-like solid below 100OC.I \.el1 above its &us-transition rernpemture (Tg), the polymer is tluid-like whicli allows it to be e:dy shaped into mai- usehl forms. nie comrnrrci:il success of polystyrene is largely due to its uanspareiiq, escellent stiffiiess, go«d prc~cessabili- iuid low çost. Typicd applications for generd-purpose polystyreiie resiiis iiicludr pacbigng produçrs. disposable medical wue, roys etc. Fom applications iiiclude eg: c:irtoris, meat-packaging tciys.

"clamsheiis" for kt-food packagine; and espdiided polystyreiie cusliioriinç mirterials for packagng.

The only restriction is in use at hi& tempenture where it loses dimeiisioiiai snbility above its Tg.

Stereoreguliinty is important in coiitrollirig the properties of pd!.mer molecules. Durilig rlic polyrnerizÿtioii of rinyl monomers (CHz=CHR) depeiiding on the iiisertimi iirrmh~meiir.;~t:icric. isor~ctic:md syndionçtic polyiners cm be formed. In the c:w of styrciie moriomer, ;i ciiidoni arrangement of the pheriyl groups alortg the backbone result in ar~çriçpolystyrerie. \Shen dl the phenyi groups are on the sarne side, the structure is isoracUc and wheri the phen. groups dternare positions above and below the backbone, the structure Ïs named syiidior~cticpolyswrene. Plese cefer to Figure 1.1 for the structural represenmtions of polystyrene.

.\tactic Pol ystyrene (iiPS)

Isotactic Polyscyrene (9s)

Figure 1.1: Structural configurations of polys tyrene

Cp to diis point, essentially dl of die commercial polystyreric in use today is ar~cticin nature.

In theory, stereoregul*~polysqrenes were predicted to esist ;md to have Iiigii rneltiiig points duc to die rigd pheiiyl groups ;ittaciied ro die polymer biickhrie. In 105.5, Litrd discovered isoocric polys-relie iuid i t did i~ideedIiaw :i hidi me1 ring point of 2-11 1.2 Lnfc)rni~ii~tcI~,rhc txtc ()f qsrdlization of this polystyrene was too slow for practicd use and it \v:is iiever comrnercidizrd. Ir was not und 1985, that Ishihara and the Idernitsu Kosaii Cu. discovered syidiotactic polystyreiir with the use of a medocene canlyst.3 -4s predicted, sPS has a higli melting point of ?70°C and ;i npid crystallization rate that is pncticd for industry. Due to in crystdluie nature, sPS results ixi a polymer with high heat resistance. This feature coupled wirh irs hydrocirboii backbone result in escellent resistance towards moisture, stem and various chernical solvetits. sPS has an uriusudly fisr crystallization rate which reaches a ma.uimum around lGO°C.= At this temperature, the rate is so fiasr. dix cold crysdliution can occur sidar to polyethyleiie tereplithdate (PET). This cipid qsrdlizatioii makes sPS pncticd for a nurnber of ÇomiLig openuoiis iricludiiig injection mouldi~iç, extrusion and therrnoforrning. Compared to odier engineering diemoplastics, it ediibits lo~w moisture uprke, lower shrinkdge aid i higher degree of dimeiisioiid ;ICLU~J~md sr~biliy\vheti rnoulded.=

For sPS to be used ;is ÿn engineering thermoplüstic, it musc he reiiiforced wirli tiber&;üs, mineral fillers and/or rubber elastomen. Fibergiass reinforced sPS lias pod dyriÿmic :uid tlienno- mechmicd properties ediibibng a high load heat distoriioii temperature of 7jO0C.= Tliese Iiigfi temperature propercies malie fibergiass reinforced sPS just ÿs effective as con\~entioriÿlengiiieeriiig tliermoplas tics.

.-ùiodier beiiefit of sPS is its specific gravity advaiinge of 35O;0 [)ver odier erigmeeriiig resins. sPS dso surpasses many other engineering resins with a higher e1ectric:d resisrmce md lowrr dielecuic dissipation putting sPS ui direct cornpetition with teffoii.= .YI of die above mmeriuoned properties, combtned with its esceprioiid electricai perfomÿiice, low specific gpviv nid tougli~iess desit competirive widi other hidi heat c~snllirieengineering tliermoplastics. ;\s a result a iiumher of applications are espected in the :uas such ;is electricd, ilutomotive, tilms :uid fibres.

In esploriiig the potential applications, the developmerit of :i re;ictioii injection mouldiii~

(RIA[) process for syndiotactic polystyreiie could erpmd die pncticd uses of die polymrr :uid the

RISI process. In the upcomiiig sectioiis, details of the c~stdliiieminire of sPS, iiisrghr mto rlic cÿdytic chernisuy, a look at conventional styrenr polynerization ;uid reÿçtiori inirctioii mouldirig pcocess operations wd be discussed to gain a berter understanding of some of the concems tn tlic development of this novel sPS RIiLl process.

1.1.1.2 Stnictural Polymorphism of sPS

Since the discoveq of sPS, there have been many snidies uito tlie nature of the crysrdliiie structure and in formation. Oiguiaiiy, Isliihua et al. repocted a zigzag piairar structure based on s- ray diffraction data.3 Today, syndionctic polystyrene has been shown to have very comples polynorpliic structures dependent on the c~sdlizatioiiconditions. Csiiig die ii»mriiçl;inirc proposed bu Guem et al., four different cqsralline fomis exist.4 .Ci a aiid P iorm a~iioiniiig planïr zigz;lg ciii~i~0 with fibre identity periods of 5.0-5.1 -4 whtle nvo others, the 8 ;uid 7, conriniiig (7/1)75 Iieliciil chahs (ITGG) with fibre identity periods of 7.5-7.7 -4. The molecu1;ir structure represenntions -are shown in Fig 1-21. The generd pattern is tiirdier complicated Li! the

fact diat botli the a (trigond) ;uid P

(odiortiombic) fimns cul esist in di fferei~t 4T in r~ modifications ch;mcterized by different degees

of structurai order, whcre a' and p' are die nvci

limiting disordercd modifications and U" ;uid P.'

.are the nvo limiting ordered moditicauons. \[arc

recently, the presence of a mesarn«cphic fonn,

coritaiiiing ch;iiiis in the t~uis-pl;u~x

conformation of srniill ;md imperfect crysr;ds of Figure 1-2-19 sPS zigzag and heiical represen tations the trigond (a)hiis ;dso been rept~rtcd.~

For simplici~,only the four major crystdliiir forrns will be discussed ;uid the coiidiriotis required to obtiiiii each fom are sfiown in Figure 1.7.2. Snrriiig frcim die i~morphousgl;issy kinn, the a fom cm be obnlied by annealhg above die Tg or by aniiedi~igthe helical 7 fom abore 181 1

OC. From melt cryscillization, puce a and P or a mixture of both cm be obrained dependuig on the

coolîng rate. For rapid cooling from the meit, the a form is obained whiie for low cooling mes or

isothed crysdlization, die crysnlline form which is obnined (a, P or mised) depends on die

sarting m~tenai.If the starting material is in the P forrn, P €om crysrds are iilways obrained. If die

srutbig mnterial is in the a or y fonthe produced material is a or j3 drpendiiig on die mi~~imum

temperature reached in the melr -and on the residence tirne at tiiat temperature. This cm br esplÿined by the fact that the a fom crystals cm eshibit a memory effect, wliicti promores self- nuclention during melt crysdlir~tion. Wheti diis memory e&ct is absent or delered ;it Iiigh rempenmres, the octhorhornbic P fom is obrined. The J3 form cm dso be made frorn soluririii casting at high rempentures benveen 130-170°C. hlost of the transfom;itions discussed 1i:ire liren from die a form to the p fom suggesting rhnt the P tom is therrnodyimiadly hroured. Cierg confnrmation andysis have Lidicated that uideed die P fom is lower in energy than die a

hlore iirerestuigiy, foomiatioii of the Iielicd il pliase cm oiily lxobtairied in die preserice OC ;L solvenr or esposure to solvent vapour. This process is hiown ÿs solreiit induced crysrai1iz:itioii

(SISC) wliicli aids cqsdizarion due to tlie eiihmcemeiit of segment mobility as a result of the presence of the solvent. In essence, diffusion is enhmiced Li? a redisuiburioii of the free volume tr) allow large-scaie structud re:umigemerits and penemtioii of solreiit molecules. During tlie crysnllization process, the solvenr molecules ;ire espelied from the cryst;dlized zones.' Tco nid rliis

SINC process, polymer solvenr interactions cm dso occur nid the degree of crystd1iz;itioii is dependent oii die nature of the solvent. There lias beeti much debate as to the iiÿture of these polymer solrenr interactions and there is evidence for the Fom~tion of solvent-rnu1rcui;ir

çompounds with a-xious solvents sucli as cldoroform, decalin, o-yieiie. toluesie, berizriie :uid cfilorobenzenes.'.8,9-10 mkes tlie solution behaviour of sPS quitc cornpies and ;it rrmn remperxture, sPS is iior soluble in good solvents çap:il)le of dissolvins ar;ictic prilystyeiie. Oiily upoii

he~ringwd th= polyner dissolve ;tnd this results in therrnoreversible gels. These tlirrmorewrsit~lt.

sels have been observed for many soivents and cm be esplained by the theos. that rhe solvent

moledes xts as helicd stabilizers, preventing the chahfrom faldirig ;uid this resulrs in enhim~ed

chain rigidity of the swoiieii polymer." This helid snbdintion has beeii esphined bu the

entnpment of solvent molecules within die helical ch.hs. The position of the phenyl groups causes

the creation of cavities that cari house the solveiit molecules. C-scd structures have been reponed

bu Charani" and Guenet'? for toluene ;wid benzeiie sPS moIecular complexes and represeriutive

structures of their possible entrapment -are sliown in Fkqres 1-23 ;uid 1.2.4. These solveiir

moledes -are bound in hvo differerit ways, loosely bound arid tiglitly bouiid. For berizerie it Ii;is

been reported that 4 molecules of benzene per sryrene monomer c;ui be tcipped. Tliret. of dit.

moledes have been found ro be loosely bound and 1 tightiy bound. Chly at die boiliiis point of the

solvent is die tightly bound solvent molecule releied. This has beeri determined bu the preserictt of

nvo solvent rciporation pek duting DSC scans of medium concenrr~tioiisPS/benzeiic gels ilii-

4(.)0h).E Due to die diffidty of rernoving the tolueiie molecules, C1i;it;uii hypodiesized tlic

eiimpment of toluene moIecuIes. Jliis eritrxpmelit w;is fouiid dso in ;i 4: 1 r;itio vid the w&gfit Ioss

by them~~~vimetricanalysis was 14.1%. Cpori removal of the solveiir, it w;ü:huiid rlint die 6 forni

is convetted to die y form.

It is important to discuss each of these forrns because it h;is beeii sliowii rhat tliesc

structures di eshibit diffèrent morphologies, wliich as a consequerice affects die mecii:uiic;ii properties of die polymer. Based on the helid coiifomiatio1is of sPS, porentiiil ;ipplicatiotis of sPS being used iis inciusion compouiids (clarhrates) have been iiivestigi~ted. Typicdy these cl;~dir,ites rnainly involve zeolites but helical stmcmr;il polymers like sPS, tliat cm include @est moledes, ;ire being considered for applicatioris for cliernicai sep;il..~tiori, purifictrioii of pes %id liquids ;uid câtaiysis.lJ Figure 1.2.3:U Structural represenation of sPS-toluene m.otecular complex &k

Figure 1.2.4:u Representation of the eouapment of benze~e molecules within sPS molecules. 1.1.2.1 Cataiysts and Mechanisms

In the earlv 1980's, I;aminshyy'sdiscoveq of homogeneous carÿlytic systerns of rne~docerir

ÿnd meth~uminoxme(hL\O) capable of producing highly linearl5 :uid stereoregul:u16 polyoleiuis, represented an imporrmt break-through in dkene polyrnerization. Since then, mera.llocenrs Ii;w become the hottest area Li catalyst chemistry, being considered the most versde ~iu~siriotimerd cadysts for the stereospecific polyrnerization of 0lefuis.1~ These catdysts are capable of prepiirriig polymen widi ntionally nilored properties by dieir ability ro control molecular weight, r~cuciy:uid melriiig point. Metÿllocenes have beeii showii to prepare IUiear low density polyediylene, ethyfeiie propylene diene monomer rubber, isotactic and syidioc~cucpolypropylene, syndionctic polystytttic and polycycloolefins. These are in tact new miiteriiils utilizing inespensive commodiy moiiomcrs diat ;LIready have es tablislied teclinoiogies for processiiig.18

In 1983, Ishihan. et d. tvere the first ro synthesize syndi«r~cticpolystyrerie by iitiliziiig ;i homogeneous orgmornenllic catdytic sys tem based on tirmium cornpouiids ;ind .Ll.\0.3 .\[os t catdyst systerns such as Zieder-Natta (2--T)catdysts bi die past have beeri Iieterogeneous. Iti ordcr to obtain uriifom activity and particle size witli 2-N c;italysts, the c;it-dysts are ofteii placed oti solid supports such üs MgC12. The most effective citalyss for syidiospecific styreiie polymtirizatioiis t1i;it have beeri repolred üre bsed on ritaniurn.' Other group IV mecds such as zirconium ;md hatiiium have been shown to cariilyze sPS but in cornparison with tiraiiiurn compourids the); show lowr accivity and Iower ~tereoregularity.~~3~Metallocenes originaily were based on die structure of

CpLSM2 wliere Cp = qclopenedienyl liguid, S = mecd ceiitcr ;uid 11 = ligand, rmgirig hm haiogens to dl+ groups. =Uthougii the terrn metdlocene is now used loosely for catalysts widi organometallic nature, for titanium cornpleses, titanocenes refer tci cornpleses widi hvo Cp iigiiids

(CP:TL\[~) and half titanocenes to cornpleses with one Cp liguid (CpTiLh). 1t is these 1i:ilf titanocenes widi one qclopenndienyl ligand that yield the highesr :ictirity hr sPS. -4ldiougli the merhod of conuolling mcricity is nor well undecstood. the basic pruiciplr is dix die irisenio~i

orientation of the monomer group is conuolled by the constrained geomeq of the bulky ligands.

The topic of cadvst design and the substitution of various ligands is quire extensive. For

purposes of diis review, only the cataiyst used ui this smdy qj-penr~mediyl~lope~itadienyltit~iiurn

uimerhvl (CpTiLled wili be discussed in denil. r\s mentioned, tirmium merdlocene compleses \di

one q-clopeiindienyl ligand yield the highest activity for sPS. \Vieri die substinienn on die

cyclopentadienyl ligmd are electron donor groups, higher polymerizatiori activities have been fouiid.=

Rj-Cp Iigmds sudi *as Cp' widi 5 methyl groups, provide an iiicreased electroii derisity ori tlie

tirani- tiius snbilizing the active species. This increased electroii deiisity or steric hindraiçc

around the active species dso cause the polymeritatioiis ro be more stereospecitic. \Yirliour die R=-

Cp ligand, the moledar weights produced by Cp-met.illoceiie polymerizarions terid to be lo-.vrr ;uid

when polymerizuig over a rmge of remperanires, a greater elfect on the xctivity cm lx olisen-çd.

This h;is been cxplÿuied by the Rs-Cp ligand's bener ability ro sribilize the active ceiiter ÿnd retard P-

h~dro~genel~mination.'~

For die systern to be active, n cocdyst is required. LIost systems h:we beeii developed wirh

.\l-\O cocatdvsr but more recentiy, novel merhydurninosaiie free cocmlysn such as H(C6Fi)i

@orme) have been shown to be effective."- Tlir cocatalyst is 1iecess:iry tOr the activatioii of rlie caralyst cornples. ;Uthough die nature and Fornition of the true active species are nor yer hlly elucidamd, it k genenlly accepted thar liomogeneous cardysts b;ised on group IV.-\ medloceiics consisr of catiotiic compleses. For die hLIO sysrem, the following mive species formation Ii:u beeii suggested Li equations 1.1 - 1.3:z5

where S = halogens or dli7.1 ligands .\Li0 connvls mounts of free uimetliyldumtnurn mLi) wliicli k important ui the dkylylïtioii (if

the cataivst. The timiurn cornplex is initidy in a Ti09 osidation srite aid reduces to a Ti(iIl) luid

rernains in this state *as m active species. This mechanism has been estetisively studied and ESR

spectroscopy kas demonsuated that this mechÿnism is highly pl:cu~iLile.~~8zJ~~It sliould br

mentioned thar the rnethyl radicals fomed cm dso initiate the ndicd polymerization of styrene CO

atactic p~lymer.-~Due to the low value of the equilibriurn consratit Üi equatiotis 12-13, the use of il

I;uge escess of MI0 is often required and it has been found espehnennlly thit large r~tiosof A/Ti

are required for high activity.

For the borme, tt has been discovered that the active comples begiiis witli metliul

abstr~ctionfrom the catalyst .as sliown below in equütiori 1.4:=.'

CpTiMe3 + B(GF;), + [CpTiMez]+ P(GF,),Me]- (1-4)

In this case, die active species cm Lie formed ordy using ÿn dhil tsmium cornpouiid. The rxio of

the cadyst to cocatdyst is 1:l md no escess is required ,as cornparcd to die hl.\( 1 susrem. T'lie

active species for this system is dso sdl in debate. ESR meiisuremerits, 1i;ive demcinsrnited rh;it rlit.

active species is still a Ti(I1I) cornples but from die above comples fornation a Ti(l\) systern sliould

be preseiit."J It lias been suggested by Zamhelli dut in the presrtice [if styreiie or solveiir, dic

Ti(l\') cationic comples cm stepwise decompose, passibly letduig to ;i TiflII) comples [CpTi.l[rl-

which is consistent widi the active species of the .ILW systern." Duriiig the comples hmtion, rlic

titanium catalyst is stabilized by the uitenction of the monomer or solvetit.

It lias heen gcncrally iccepted diat tlie rnecliaiism of polyrnerizatioii is ai insertion

mechanism is shown in Ficgure 1.3.1 Initiation and propagauon occur together, in die seiise diar once

the [CpWTiMel+P(C~FS)~~[~]- has been formed, the styene monomer coordin;ites wirh the Ti centcr

and tliis auses cis-openhg of die double bond side (side \vith the wo 1iydrr)gens) ;uid rlieri tlic

methyl group amches ro die P-cxbon. The nest monomer rliar c«rmliwtes t» tlie tiruiium cciiter dso hÿs cis-opeiiing of its double bond :uid d~endie polymer segneiir anaclics to rlie P-cirbon. -nit syndionctic contigur~tionuises from the phenyl-plienyl repulsivr inreractiori bçnvçeii die lasr

inserted unit of the growing chah and the incotning rnonomer.

In rnedlocene catalyzed polymerizations, terminatioil ractions arc geriecdly coiisidered

absenr." If the polymerization mecliïnisrn was dyliving, molenilÿr weiglit distributions of 1

would be found. This is the not the case, since P-hydro~nmsfer reactions do esist which limit the

rnolecuiar weight. The existence of these reactions have beexi detected by gas ccliromtognpliy afrrr

queiiching a reaction with methmol.' The preseiice of ethylbenzeiie suggested thar retniriariori ri:i :i

second-. insertion occurs after a P-hydrogen elimiiiation. The preserice of ri-propyl beiizeiie dso

sugges ted a second,q mechanism, 2,l head to nil insertion mech;uiism. The P-h ydrogen eliinixiirioii

scheme is showii in Figure 1-32 Broidenuig of the mole~.ul;uweight distributions aui idsu occur

due to different caraiytic cenrers, esistence of diain trader and fornirion of aPS due to r.idid or

ionic initiation. hIechanisms that wouid ause temiiiiation, c;üi occur by iiiclusion of car.dyst

p,micles within precipitated pol !mer and deactivatioii of the active c;it;tiytic si tes.=.'

h[ainlv we have been discussing the catd~iciictivity of the CpTiMes. Tlie B(C:hF5)5 ;dotic.

in the preserice of a countetion (probably a trace imouiic of wter) h:u ;ho beeri sliowri to be ;i good

c;irbocationic initiator for ethyl vinyl ether cmd sryrene.- The bonne itself will slowly prilyrrierrizt.

sryrene to low rnoIecular weight ;iPS. In most of die reported Iite~iturepo1ymeriz:itioris ui the

presence of a soIverit, the anctic palymerizatson was rio t sigriificm t. Hawever, wid~aiiy devia tioiis

from a 1:l cataiysr/cocataIyst ratio with additioiiid borme, increases die frxtiori of aPS formed.'

Interestingiy, for the Cp'TiAIes aiid borme system, it lm beeri reported bu Baird et al., rliat a

dud nature to die cadysr esists. The system cm polymerize die siune monorner by wo differciir

rnechanisrns, a carbocatioriic polyrnerizatiori mechmism ririd il Ziegler-Satta mechanism. For styrene polymerizatioiis irivolving toluerie as a solveiit it w;is showii th;it ;uiy polymeriz;irioti rif styrene below O°C resulted in the formation of iio syidiotactic polymer md only iitmic." This phenornelia tvs iitrribured to the Iow concentrarian of the sPS actlvc cornples iit tfiese tempecitures

.uid conttnuatioii of die po1ymeriz;itioii t~y;i c*xt~oc;itioriicmechiuiisrn. Figure 13.1:27 Me tal-coordina ted insertion mechanism of s tyrene

Figure 13.29 P-bydrogen elirninaaon reaction in styrene poly~nerizauons In the developmenr of die sPS RIhI process, it is evideiit di:ir tlie cadysr cliemistry will pl+-

a significant role. Having uisight uito the fomxion of the active species md its polperizÿtloii

mechanisms will help to esplah and understand in canlyric behaviour under differenr conditiuiis.

The observed resulo from some of the different polymetization coridiùoiis will be presenad in the

nest section.

1.1.2.2 Effect of Pofymerizatioa Conditions on Catalyst Activity and Matehl Properties

Tliere have been mm? studies reported regarding a vÿriety of different cardysr systems md as the active species and mech;inism are being elucidated, bener and more eficierit cadysrs are beirig discovered." For die purpose of this review, climcreris tics of tlie CpTilLe3 / B(C6Fï)s the sys rem used in tliis study wdl be focussed on but other similar cataivsr s'terns will be discussed. Ir must Lie noted that most of the dari reported are for solution polynerizxioiis iii rolueiie ÿiid tirnt very litde buik polymerization dan is adable. Alrhough die dan is reported :it :i varie? of monomer ;uid cataiyst concentrations die effect of die polymerization conditions and b~nerxltreiids sliould t~e comp-xible.

Tlie oti@nal discovery of sPS udized AL+(->;LS a cocariyst. .\LA(> is curreiitly Lieiiig widely used but its activiv tends to depend on the .LM0 composition wirli a 1;rrge escess of .\Li0 required for optimum activity." The use of B(GF~))Jrequires a 1:l ~~td~~t/~o~iltdy~rratio. For c~mparisoti.

ChieiiLJ lias reported tlie effect of .il/Ti ratios oii die sPS yield utilizirig die Cp*T~\[e3cacll~st ;is shown in Figure 1.4.1. It cm be seeii that a ntio of500:l iU/Ti is required br optimum acrivity I~ur in geneni die yields are quite Ion- for the reported coiiditions. For the oprimized C~'TL!I~J:L\( ) nrio, the acriMty wïs reported to be 1.22 r 106 g I>S/rnol(Tï) wliile in die s+mesmdy, 3 R((J,Fi)3

çatal~*zedrwction, had n calculated activity of 3.83 r 106 g PS/mol(iÏ) \vliicli is 3 rimes Iiislier in actiriry. The reason for the lower hLI0 ncuvi? is due tri the lower efticieiicy «i esrrrictirin of rlic methide ion. The efficienq of the esuüction eshibits ;ui optimum ;irouiid 500:1 .-U/Ti ratio but inconsis tenq occurs at Iiidier .il /Ti r~tios.1 t lias tieen siiLggestedrh:it çr>rnples;itiriiiof the ;icrire Figure 1.4.1:a Styrene polyrnerization catalyzed by CpTiMe,/MAO Conditions: [CpTiMc:j = 1.0 r IO--'M, [styrene] = 0.8 hl, 50 t11L tcilucuc b = 60 uiiii. Tp = 50°C ions cm occur ,and, due to stetic reasons, dedie catalyst system less active.3

Tlie higli activiq of the CP'TL\I~~/B(GF~)~has beeii reported by odiers and diese diors

have fourid the syndiocictic yield (fraction uisoluble in ,LlEkJ, to be higti, Lietweeri 97-Ocl wt. ",O. Ilic

resdting sPS dso found to be sterically pure by NhCR wliich w;is continned bu ;i higti meItiiig

Zmbelli, recentiy preserited ai in depdi kuietic study of die Cp'Tihk3/B(C6F+ sustem ici

coluene solutiori, in an attempt to eIucidate the nature of die active spe~ies.~'.-1s CO the proposcd

mech;mism of reduction of (CpTiXie2]- to [Cp'TLLleI-, it was found t1i:it iipon the addition of

syrene, die estent of reduction depended on the concentratiori of moriomer. It was hund di;ir rhc

concentration dependence on the monomer was first order. .\c prescrit. it is the oiily snidy itir.nl\-ing

die CPTL\I~~/R(G,F~)~cacdyst svstem under a range of conditions of low +-relie coriceiicr~tioiis. short polynerization cimes and a&room tcrnpermtre. The effect of styrerie concentrxior~or1 die polyrnerization is showti ui Figure 1.4.2. -4s espected, incre;isiiig die styreiie coriccnmtinii resulrs in ;i higher cunversion. For this 5 nun room temperature polymeriz;itiori, weight iivcragc moleculx weiglits produced were around 2(.)0,(J00 g/mol widi polydispersi tics migirig hm3 ) - 2.6. (3p'TLL les / B (G F3)3

O 0.2 O -4 O -6 0.8 1 1.7

Sty rene Conceiitration (mol/L)

Figure 1.4.2:31 Effect of styrene concentration on the monomer conversion Coriditions: [CpT&Ie,l = 1.1 a 10-3 hi. TiB = 1: 1, 35 uil. oftoiucric, tp = 300 s, Tp = 25 OC

Tlie eEect of increasing polymerization rime wÿs dso considered ÿtid die results are sho\tm

Li Figure 1.4.3. .ils0 as espected, increÿsing polymerimtion tirne resul rs in Uicre-ased amversion but it

O 100 100 300 400 500 600 700

Time (s)

Figure 1.4.3:Jl Effect of increasing polymerization cime on the monomer conversion Coriditioris: [CpTi\le:l = 1.1 x !')-: LM!,TiiB = 1: 1, [Styrcuel = 1.09 tiiol/L, 35 iiL of tolucrie, T, = 35 OC

Campbell et d. at Dow Chernical Co., liave reponed data for il cirkty of complcscs

results show diat catdvst actiritv cm be miritained hr mm: haurs, dthougli thet rate of polymerization does decreatie widi tirnc. Tlie effect of increasing polperizatio~itemperature uns dso snidied bu Zmtielli Iiiir

unfominately, it was for a, CpTi(C)B(CF) catdysr sy~tern.~l Tlie gened r ffeçt of

ampenture on the conversion is showi in Figure 1.4.4. .Uthougli diis cadyst system is sli@id>- differenr thui die CpTLVe, systern, it mi be seeii that die highest acriviq is reported around 70°C

Temperature (C)

Figure 1.4.4:" Effect of increasiag temperature on the monomer conversion Conditious: [C~TI(CH~P~~)~J= 1.1 x IO-!hl .Ti:B = 1:l , [Styrriiel = 1.09 riiol/L. 35 tiL d toliierrr-. tp = 600 s This suggesrs a temperature dependence o C the active palymerizarion speçies, widi dr~cti~itioii occurring at Iiiglier rempentures due ro thermal decompos irion of the org..uiornerdlic comples aid :it lower temperxures, a lower conceiimtiori of active species due to slower tmisitioii of tlie Ti(l1) rri

Ti(III) species. The effecr of molecdar weight with temperature showed ï drmiitic decrease in molecuiar \veighrs to 30,UOO g/mol atier 70°C but eshibired no c1i:uigs in the IWD. Sever.d

remperaure but a sligl~dylower optimum tempennire for Cp systems ;uouiid *OC. presumdily due

CO lack of methyl groups to snbilire die Cp rÜig.s'JOJ= Ir was iilso ol~sen-eddm tlie nmlecul:ir weigtirs tend ro drop as the ce~ctiontemperature is incrc'ased. The effeçt of molecul;ir weighc ;uid temperature \vas tiirther studied at a varie? of tempecitures for a

(ten-bu~l~clopen~idie~~~l)tir~i~umcÿrdyst \vit11 .LL40.J3 Tlie resiilts ;it (i°C, ?i°C ;uid 0-5O(: ÿrourtd U°C. .At higher tempenmres, they found that the stenc purity of the syidiomctic fnctioii

decreases with increasing reaction ternpenmre as contimed by the decrease in melring point. It w-as

also observed that the tempenture dependence of die '/O syidioractiç yield was Cowes ui iiarurr

eshibi~ga masimum ît -lj°C. The temperature dependence of borh die melting point ÿrid '0

syndiotactic yield are shown in Figure 1.45. It wu suggested that at hi& rreÿction temperatures, rlie srndiospecific acti1.e sires change into ÿspecific sites which causes a deçrease in die syiidiocictic +Id and lowen the melting point due to an increased -mount of monomer insertion errors. Tlir rise iti activity from lower tempentures was amibured to die gredter conceiitcition of syidiotactiç active

Figure 1.4.5:" Variation of syndiotactic yield (0)and melting point (a)of sPS versus poiymetization temperature 1.1.2.3 Nigh Convenioo Sryrene Polymeriza Lions

For most of the studies reported so far, very few have reported the conveniori of styeiir ro tiigh dues Li the dilute solutions used. Low catrlyst and monomer conceiimtions in roluene solution were used to improve heat tnnsfer for bener temperxure control .md to increÿse [lie

Huidity of the reaction mistuce due to die tremeridous viscosity iiicrme at Iiigfier conversioiis.

However, some artempa have been described. Ishîlim reported for CpTiCI3 and CeTiCl3 /.\LI(1 sustem, nearly 100 wt. o'. conmnioti, at a styrenr çoncentratioii of 1.7 .L[ and catdyst conceiimitioii of 4.2 s 104 M, when the reaction wris left for 2 lics.3u Chien dso reported up ru '14% coiiversioii using a CpTi(0Bu)j -and hLAO.32 ;\t a styrene concentration of 2.9 hI at 6iJ°C mid ï cadysr concentration of 8.3 s IO-' .LI it was reported die stir bar in die re~crioiiressel ceïsed tliictir~iiiiig fter 5 min. Iiiterestingiy, the highest conversion reported by zunhelli is 107°.'~in 8 miriurrs for :i reaction ït 9i.i°C for Cp.TiCl)/hLi\O system, at a c;miyst cot~centrationof 9.1 P 10-~.II iuid inrelie concentr~tioriof 3.3 M ;~t9O0C.=I This 1U2Oh m;iy be due to weighuig errors, but ir would be mteresting to deduce whether it was due to entr~ppedresidud moiiomrr or solverit. For rlic

Cp-TL\Le3/bome s ys tem, Baird er d., report pol ymerizütion dat;i ïr die Iiighes t catid !*sr md monorner concentr~tioris.~ The? utilized styreiie coricetitr~tioris of 4.3 ht ;uid c;it;dysr concentrations of 7.5 s 10-3 ht whicfi is 10 to 1(.i0 fold the -mouiit uscd by odiers. Theu obsend

tliat the reaction mismres solidified withiri seconds vid coiitained 15-20 wt. "'0 trapped moriomer.

Cnder these conditions, the cmde material coritained relatively smdI wnouiits of ;iPS, uid the sPS had melting points of 27Z0C, with moleculv weights raiging from 100,000 g/mol at 7iPC md

3,üoo,0~1Cig/mol at ii°C with polydispersities ;irourid 2.3. î.2 Con ventionai Sryrene Po~vmerizarlun

1.2.1 Thermal and Bulk Polymetization of Styrene

During the dycomrnercidization years of polystyrene, tlie rdre of polymerization of styrene w;ls fcightenlig. The high rates and the resulting esothermicity delayed some of die eïrly development because of apparent uncontrollable rmctivity. Irihibitors such as t-butylcatechol werc necessq to prevent high yield losses during distillation and storage. Tlie Tint commercializîtioti \cis by a themal bulk polymeL-ization using Dow Chernicd's "Gui" process wliich uiwli-ed tillitig 10- gdon cms with monorner and hating the cans at progressively h&er temperatures for seved days

CO rerch 99O6 con~ersion.~~

The styreiie Fdyof monomers is unique because of dieir abiliv to undergo spoimmous or thermal polvmeriz~tionmerely by heating to 100°C or above. Ciider appropriate polymeriz:iririti conditions, styrene cvi act -as its own initiator. Styrene monomer cm geiier;ite eliougli free r~dicds during heatitig tliat high conversion and liigli moleculxr weigtit polymer cm be prepared widiour rlie use of chernical initiators. This mechariism of thermal polymeriz-atiori 11;s beeti proposed ri] proceed by a dow Diels-.Uder dimerization ceaction, wliich is then able to hm mriiior~dic;llscip;ible of in~tiütingthe styrene polumerization. The hvo steps -are shown in Figurcs 1-51.

CH,

Fig. 1.5.194 Thermal Initiation of Styrene The nte of rhis themial polynetization has beeti showii to follow die relatioiisliip:

Initial rate (WL O/O poiymer/hr) = 10['uj-a170/T(v]

.it lower temperatures below l0iIoC, the rate is quxte slow and has a zero order of ceaction. For

60°C, Russeil has repocted a me of 0.0070 mol/L/hr in die absence of oqgeri ÿnd inhibitors wliicli is approximately 0.073 Oh (wt/vol.) per hour of anctic polystyreiir.J5 Today, die comrnercid use of the thedpolymerization of styrene is quite uncornmon and insteüd, free radical initiaton sucli as

72-azobisisobutyronitnlr (rUB;'I) are often used. The propagation mechaiiism for chin gniwdi of polystyrene occurs predoininandy by head to rd addition :uid the iiiirinririg sclirme is slir)wii 111

Figure 1.5.3. The additioii occurs Li a Iiead to rad addtioii because of die seÿter snbility of die benzylic radid over the methylene radical.J4

Figure 15.2:3' Chain Growth Propagation of Styrene

Tvpicall y, the bulk pol ynerization of styreiie hivolves die process of formirig pol ystyeiic from pure, uiidiluted monomer. It usually involves the processiiig of ven viscous tluids brç:iusc polystyrene is soluble in its own monomer forming :i single continuous liquid pliase. Oiice ti1gti molecular weiglit polymer is fomed, viscosity iiicreases up to lu4 or more cm occur. In iiidusrcy, solution poly-nerizarions are often used by the addition of j-lj?r solvent as ;i processirg üid to reduce die riscosin ÿnd to provide chah uyiskr agents. .Utliough the use of large volumes of solvent mi- seem attractive to :moid high viscosities ÿnd ru colirrd the tempenmre, ve? téw successtiil processes have beeii developed in diis manner. hi interesriiig feiture of biilk po1yneriz:ition is the Iiigh esotherrnicity. The typic;d lieat of polymerizatioii of styeiie is 70 kJ/mol aid a cd~uhtioiiof the adabatic tempemure cise results in ;i t1ieoretiç:il temperdnire rise of 33i0(:.3f1

Durttipj pn~cessiiig, 1n;idequ:ire hcit remov:d resuits in :m sccelecircd rc;icrioii ;uid iiiçrmsc III temperature. This large generation of heat, coupled with the lower themd difisivit). of the rwctirig miunire, often leads to thed runaway. This rnakes the process very diffi~ulrtu control since the rise in temperimre lowers the degree of po[ymecïzation. This causes the molecuiar weigiir distribution to broaden during the course of a reacuon which lads to a deterior~tionof the mechmical propertïes of die polymer. It is undesirable to have thermal niriaway since the rmctiori misture usudly approaches a ceiling temperdture where monomers vid polymers are in equihbrium.

For styrene die calculated cehg temper-ature is 310°C." The polynen recovered after thermd niri;nvay have low moIecular weight ;uid are of linte comrnercid value. For practicd resons, m;uiy reactors have autorefrigeration systems rhat limit the redctioir tempeciture below the boilirig poitir of the monomer (for styrenc 14S°C).

1.2.2 Diffusion Controiied Phenornena

-\s ;i continu;ition of the previous discussion, the lknitirig fe:itures of bu1 k pol~meriz;iriclii gves rise to the serious problem -ssociated wttti high viscosity systems rliat quickly becorne diffusiciii controlled.

Tfie most cornmon cliw~cteristicof buik polymerization 1s die preseiice [if hi& moleci11;ir weighr polyrner in die conrinuous phase whicli gves rise to l;niri;ir-tlow systerns witli m;iss vid he;ir transfer limitritioiis. It is well known for the free-r~dicdpolynerizatiori of triiiyl moiiomers such ils me thyl methacrylate and sqretie, thüt c1;issical pol ymerization kinetics do iio t appl y at Iiigli conversioris.38 In die moderate coiicentration cmge wi th coiiversioiis greater thui Gi PO,die cite r )f propagation Lg-aduallydecreases as the reaction proceeds and die concentrations of monomer ;uid initiator are slowly depleted. However, for systems witli Iiigti moriomer coticent~irioiis,;ui acceler~tioiiin rate is usually observed. \Chen the polymer coriceiitr,itioii becomes tiigh enou&, dit- growing polymer chairis wiii become erimgied witli segments o€orher polymer ch;iiris. .\s ;i resulr, the mobility of the polymeric mdic;lls decreases ;uid the probability of them ericouiitering rnoriomcr decrc;ises. The prop;igatioti rc;ictiori invol\-es the re;iction of ;i 1;irgc r;ulicd ivirli a sm;iiI rnc~iic)n.icr molecule whose diffusion is nor changed significmdy whereas the rermuiarioii process involves WU rnacroradicals whose ends have reduced rnobility, because motion of tlieir ceiiten of rnass lias become restrained. The net result is an effective increase in the me of polymerization. This

;iutoacceleration phenomenon has been termed the 'gel effect' or Norrish-Trornsdorff effect. Tliis gel effecr causes a fàsrer tempenmre rise and fasrer initiator decomposition. In addition to this pl effecr, anorher diffusion conuolled phenomena cm dso occur cdled rhe '$;iss effecr'. This occurs when the polymerization mixture vitrifies and die propagation step becornes subiecr to difhsioii conuol. This usudly ocnin below the &as trmsition of die system (misture cif monomtx xid polyner) ;uid causes poly-nerizations to case before dl the monomer in the system Iiÿs ken consumed.38

Esperimeiital evidence for die gel effect cm be seeii -as a rise in siope in a plot of moriomer conversion versus time. At low conversion, wiiere classicd kirietics (steady-mte ;ipprc~simarioii) applies, rhe conversion increases pddy. .At sorne coiivenion, the mqnitude of which drpeiids on the monomer and other factors, die polymerizatioii rate bepis to iiicrease ro A mucti tiigher levcl. resulring in 2 tiigher dope (see Figure 1.6). The iiicrased conversion rare usudly leads to ;i

500 1O00 Timc (hrs) Figure 1.6:39 Effect of Diffusion Connolled Termination Bulk Polyneriziition of Styrene ~t 60°C witli .URS (0.09 I[) temperature cise, which causes a Fer higher coriversion rate dut dso muses a higher tempwinire etc.l8

described so hr, there are muy cornplesities in the polymerizatioti of styrene. Klien de-ding with sPS polymetizations the hctors to consider are the metailocetie cataiyst chernis- vici charxtersstics, dieand uiitia tion, and di fision control and the type of cqsnlliiie polmer t'omrd. hlmv of rhese hctors myplay a role when uivestigating and developinç a MAC process. 1.3 Ri1MProcesshg

1.1 Introduction to RIM

The following is a summan, of some of the mÿin highliglirs :uid kitures of RIh[ processiiig

:ti isutfàied by the extensive compilation wrinen by C. blacosko."

Reaction injection modduig (MM) is a polper process for the npid production of complrs plastic purs. The process involves the impuigement of nvo reactïve liquid cornponeiits iusr brOm rhey are injeçred üito a mould, die shÿpe of the finished part. Durliig inisirig iuid füling tlir rnould the reacrioii misnire usudy p«lymenzes r~pidly.Once the po1yrneriz;irioii is cornplrre die polymer ts cooled md the pm cm ofteii be demoulded in less dian one miii~re.~~*

-1 tvpiç:il MM schem~ticis siiov.m ui Figure 1.7. Tlie RIll prucess is riirirely :L b:ircli operation. The process involves the delivery of nvo or more liquid rextuirs from sror+r,e raiks.

From diese r:uih, rlie liquids *are purnped at hi* pressure iiito a misbig cliÿmber. nie Row cirio brnveeri die nvo srrem 1s caretLIIy metered to maiirain die stoichiometric bdmce rif the re:icraiirs.

Line from cornponent storage Dry Hydraulic tank air cylinders

Lance metering zylinders

Ihtet tine

F7ecirculation line

I 1

Figure 1.7:1' Schematic of n RIM process Irnpingernetit in the midiead then ocmrs which causes intensive misuig of die rextioii srreÿms. Tlir materid polymerizes as it flows out in to the mould cavity, which typicdly tkes about 5 seconds-

Once the polperization is near completioii or solid enough to withscuid the stresses of demoddirig, the part is ejected. This demouldlig usually ocmrs beweeii 0.5 - 4 min depending on the s!-stem.

The part then undergoes fiiiishhg processes to flash off the volatiles and postcure the mrerid. jlfter the pan is dned, it is cleaned *md then ~ainted.~O~

One of the main advanmges of MM is chat it k not a veq eriergy intensive process. The kev to MM processing is the activation of the reactioti by impüigemeiit mising of low viscosi~liquids-

This use of low viscosity liquids avoids the high remper-tures rind pressures required by convcritiuiid themioplastic injection moulding 0.In TIN higti temper-tures ;ire required to iriiecr the viscous molten polymer into moulds usirig pressures of 100(.1 bar and 31iOO ton c1;unping hrces. For

RL\L, the mould tempemures are usually benvreii 50-80°C, die siunr temperature ;ü die st;irririg rcactmts, and pressures for irnpingement mising are only 10r 1 bar and the sliimpiiig forces oiil!- 3 1 tons. .\fter the rnisuig, pressures of less tliaii 1iJ bar are required to fil1 tiie niould sirice die rniitcd 1s still ~OWin viscosity. These low pressures dlow smdler mould cI;imps to Lie used. Tliis 1e;ids to Icss espensive tooling and opention especially when produciiig large p;i~-ts.~'~

One of die major disadvanrages of RIA[ is that longer cyclirig cimes ;ire required wlittii compüred to Tihf. Iri TIM, parts cm ofreri be demciulded in 30 seconds ;uid rio specd materid h;indling is required. Besides the toxicity ofsome of RIM reageiits, diere are difficulties in seding rlw svstems *and in some cases, the atmosphere musc be kept free of oq-geii and water. -hotlier disadwitage Lc that specid mmould relme agents are required suice the re;ictivc materid sometirncs adlieres to the merdic mouIds?0c

Xinetv five percent of die m;iterids processed by Rlhb are typicdly polyuret1i;uies \vlitle others include pol yes rets, eposies, tiylotis iuid dic).cIope~it.,idieties. 1los t r) f the polyurcrli;uic mateciais ;ire e1;iscomeric and structurd foams whicli Iii~ve hund tIieir bigest ripplicacioii in dic.

.lutoinorive iridustry for bumpers ;uid h~cia.~MPoly~rerli;u~e cliemisrq- i~ivolvesthe cr)iidcns;itioii reacuon of diols ÿnd diisocyutes. The chemisq is quite suir.ible fiir RI.11 silice die kinrrics :ire npid -and nead? 100°h convenion cm be xhieved. The focmularimis of polyurediÿiie are quite versaule in that crosslinken, oligomen ÿiid cliYn estenden cm be added to rdor the proprrtirs of die polymer. To hrther irnpmve the dimensioiid snbility and mech;uiic:il properties of the pms. the option of adding minenl fiers or giass fibers into the reactmt feedstreams is used, ladbig to ii process called reinforced MM ~iLL).40e

.is meiitioned above, the key to a Rihl process is the impiiigemeiir mising of die reictivc

Iiquids. ;Utiioub,$ there ;ire mi. mishe-ad designs, it hÿs been fouiid tliat n 'T' miser, as sli«wii iii die Wh[ schematic, is efficient-JOfTo mesure the effectiveness of the impirigemerit misirig iui rstim;ition of the Reynolds number (Re) is often used. The Re is a dirneiisionless vdue of rlir ~iriooI the inertial forces to the viscous forces which include die effects [if dow rxe (0,derisity (p). viscosity(q) -and cliÿmber diamerer (d) -as sliown iii tlie equation below:

For polyurethÿiie cliemistry, Ahcosko lias fouiid thnt die vdues of' Re should br grexter dim 300 iii order to gve good impingemerit misirig for a RNpr~cess.-'~g

.Liother factor dependent on good misiiig is tlie masimum adiabiiric remperxurr nse. In gened, the €!aster the mising, the higher the peïk temperature wliicli :ho correspoiids to a ge;iter

Reynolds numbrr. The irnpomice of rnislig is to reduce the s triatioii rhickiess. S triarion rliichies'; is irnpomt, süice the lmellar mode1 of rnisiiig geiientes a disrribution of thichesses. Tiiiii sui;itions ;dlow monomer to difiise md react to tom polyrner wliile 1;irger striations cause stoichiometric imbdances, which dow monomer to becorne tnpped benveen tlie polyrner 1;iyers.

This is usudy chnrxterized by slower misirig rates and leads to a lower peak tempecintre. Brner mising, leads to Iiigher molecdar weights ÿrid ;i higher tempermm rise wliicli increase die re:içtioii meto drive the reaction to complete con~ersiori.~~~~ 2 RIM Processing Requirements

-4s rnentioned previously, most of the RIhl producn have Lieen bÿsed on polyuredivie

chemisv. This is a condensation polyrnerizatiori method uid is vsrly differenr hm dic

coordination polymerization method of syndiotactic polystyrene since iio c~dysris required md rlie

monomer is consumed irnmediately upon miwing. However, Li 1983 Hercules iriuoduced die iirst

polymer which \vas invented pÿmcui~xlirly for RIiLL.dhC Polydiqclopeiir~diene (PDCP) is ;i

crosslinlied polymer which forms by a menthesis ractioii of the iiorbomeiie ring of the

di-lopentadiene (DCP). This resuls ui a poi~erwith hidi modulus aid hi& impact strengh.

t\h:it is interesting iibout this rextioii is that ir utiIizes î coordination npe of catdyst. hvc~p~rt

RI.\[ system hns been developed, in which a tuiigsten chloride c~tÿlptdissolved in DCP is miscd

with a diettiylduninum chloride cocardyst in î 1:l r~tio. The reactioti of tliese nvn liquids is

estrcmely ripid ;ind esotiiemüc, to die point diat inhibitors such as di-si-butyl etiier are dded ro

dela! the torrnation of the catalytic comples. The cidiab& temperature rise for DCP is above 20O

OC. For die successfiii, DCP RIhI fomul;ition, ii few additions 1i;ive Liecn miide. The ti,miul;ittoii is

shown ui Table 1.iJ. Tlie catdysts are sensitive and must be protected frcim risygeri aid wter. llic

94 wt. O/o DCP 94 wt. O" 5 wt. ",'a hton 1103 S \m. O%

0.67 mol O'O \Y/'CIa/pheiiol 0.1 mol "'O 1.0 mol O/O toluene 1.5 \m. O,'O benzorii trile o. 11 mol O;'~

Table 1.0:w DCP RIM Formulation

reacrants ;ire kept at 35OC. hton 1102 a syrerie-buudierie-screne uitilock copolymer ts ;tiso

dissolved in the reactants, not otilp to imprcnve impact resisr~icebut ro incresse die rcacr;uir

viscostty. This increase in reacrant vkcosit)r reduces the air entmpmeiir duriiig filling ;uid the ;unount of t1;isiiing th;ir ocairs. The orher companents suc11 as die tr~luetie.pliencil ;uid I~ciizonitrilc;ire required to help solubilize the \%'CIo cadyst ÿiid ro preverit prepolyrneriziriori. For tlie most pm,

there -are man. sdarities ui cornparison with the mentioned syitliesis mrthod of syndioaçric

pol~yrene. -4ithough PDCP differs €rom sPS in that it is non-crysrdluie -and crosslinked, ir dors

have a hi& Tg of llo°C. It is also prep-xed by coordination polyrnerization, which is simpler diai :i

urediane polymecization. Msing should be easier because of the cliatri polymerization mechmism chat does noc require perfect stoichiometric Liiilan~e.~Ol

In the development ofï non-urethane sPS MM process, hl:icosko40* lias outliiied some of rhe requiremena for ï material to be successhi of which some ÿre listed beluw:

Reacmts must be stable for weeks at room tempemture

Condition of m;ichuie should operare ït less diaii 70°C or 15U°C for Iiigli ternpccinire

machines

hlising of nvo ceactive components but ;i diird ma- be added

Low viscosiy to dlow good irnpirigemeiit rnising

hIust have ai increase in riscosity after inisirig but dlow tirne for mould fiiliris, so as ro

preverit bubble entnprnerit

Khile ~fing,a low mould rempermm should Lie uscd wirli ri« polymer deq.idxioii biir

compensation for shrinkage should be allowed

Demouldirig rimes sliould be less tlim 3 minutes or 45 seconds for higti production

95% conversion should be achieved vid have sufficient green streriL@ifor demouldiiig

Little or no flashing of the volatiles

nie post cure should Lie miiiimized and the product sliould 11e pïirit~ble

Csirig the basic fuiidamentais of RIXl and noting die corisider~tïoiisoutiiried bu .\ Iiici~sko. the development ofa RIA[ process for syndiotactic polystyetie seems feÿsitile. Givrn the simi1:irirics in tlie DCP polvmerization, the adaptation to a merdlocerie RIAI process sliould be possible :ü \vil1 lie esplairied in the followiiig section. 1.33 Previous studies of RIM Processing of sPS

Observations of the mpid kinetics of a sPS polymerizatioii, gwe rise to die tdea -id possibility of developuig an sPS RI&[ process. The npid production of engiieering parts hariris the liigh crystailine me1 ting point of sPS is seen s having great potentid and cornmerciai due. l [ÿny of the elements of a RI&[ process, such as iow viscosity monorner, nvo reactant strem, npid chernical hetics and quick soliditication are preseiit and the adaptatioti seerns fiisible. The motivltioii behind the worh is CO produce high value, etigineering thermopl;istic puts from a cnmrnodin- monorner, s tyrene. Baker et al. pioneered the sPS FüM process in 1994, discoveritig somc shortcomings but dso considenble promise, meeting miyof die requirerneiits hr;L RIXL proctts~.~~

The initid investigations into the sPS RIhI process beputilizirig a bencli scde RNdevice.

The ripp;iratus was senip under inert aunosphere conditions ;uid dl materid hriridlirig wu ins~dt.;i

$ovebox. .\ CpTiiiIe3 c;ztaiyst vid B((>F+ cocataiyst sysrem w;ti used ;uid the niaterd w;is dissolved either in sryrene/toluene or styreiie/styretie. The solutiotis were irnpiriged in LI miskici and the styrene polymetized r~pidlyto tom crystdlirie sPS. It w;is reported diat moiiomer

conversions varied from 72 to 83°:'o. These coiiversions were well lielow die requiremciit of '15" 4, conversion as outlined by Maco~ko.'~k hhiy uivestigirtioiis were irito iticrefiiritr, the conversion. -\t first, they believed die crystailinity to be die limitiiig Eictnr with monomer being mpped widiiii die crystdline chaim. Copolymetizatioiis with 3(4) mediyl-styrerie were made uid rio significant inprovernent in the conversion occurred. However, polymeriziiig 3(4)-rnethyl styeric done did result in a Iiigher conversion of 93Vo but resultcd in the Ioss of o~yt;ilIiiiity. Sest, dic effecr of c;itd ys t coricentratioris was uivestig~tedin die i~icreasirigcuige of 1:57( 1 to 1:3 c;italvst to monomer ratios (mol/mol) vid it wu tound, rit best, that 89O,/0 convcrsiori could be acliieved. ,-\ few novel techniques were dso attempted, to iiicretise the ccin\*ersioiiby impartiiig energ to the rt.;icttiig sy~rern.~~HF subrnergmg the mould in ;ui ultrasotiic water bxth ;ui iricre;ise in airit.ersiori rn '1 l"e w:is tolind. .As a pst curirig technique, bomtxirdment by neutron r;idiatioii W;LS artcmpred tr) polymcrixc. the residuai monomer. It wris found rhat 93% conversion wis acllieved lifter 124 1 min of Ïrr-diatioii time. A more faible process investig~tedwas themai posr mring. By seding the plug UI rpo?

md placing them in a vacuum oven at temperatures of 180°C and above, it \vas found, ;ir besr, 5'' 11 residual monomer was left for the 10 min trials but afier 5 lirs, 1.5"'~ residual monomer remairied indic;iting that significuit anctic polymerization had ocnirred.

htly to deal with the issue of sPS bcirdeness, &ton Cl652 mbber succrsshlly dissolved in the monomer catdyst streams in the range of 10 ro ?O wr. S'O ;uid polymerized ro hm solid plup. It wvs fouiid rhat odv the 10-15 wt. ?O results were promising siiice gmss pliase sepanrion occurred ar higher weight percenrages of bton. From SE.\[, ir was observrd diït gmd dispersion wm achieved with ÿn werdge size of die dispersed p1i:ise beitis 0.15 p.43

It \vas concluded the sPS RIM process bad corisidenble poreiitid. However, die! did iiorc that the maior problems of iiicomplete coiivenioti of the monomer aid die st~bilityof the c:irdysr would have to be irwestigated hdier. 1.4 Aims of tltu's Sm*

In the punuit of achieving higher convenions in the sPS Rihl process, it was fel t that ceniiii hndamentai questions should be investigated. A smdy of the effect of rextion parmeters sucli ;s rime, temperature aiid the estent of mising on die conmrsioii and dso on die sPS material properties wouid give insight into the nature of die ceacting system.

To obnin :i bener understmding inro die nature of the coiiversioii limicition of the RIAI SI'S pcilymerizations, the following objectives were outliiied:

ro derermine if die styene rnooomer coiivenion of the RIAI sPS polymecizatioii am bc

dtered by the estent of misiiig,

ro determine if the monomer conversion of the RIhI sPS polymeriz;itioii am be iricre~sedII-

longer reaction timcs,

ro smdy the effect of the mould wdl tempenture on the moiiomer cotivenioii of tlic RI.\[

sPS polymerization

to de termine die effect of die above re~ctioiip'xameters on the polymer properties sucii ;is

the sPS fr~ction,melcing point, ucticity ;uid molecular wei&t,

to discuss die rianire of die cotiversioii limitation in ternis of eidier beirig difhsicjli Iimircd.

tempemture limited or intluenced by ;inorher factor such as die cryrdliiie iiature of sPS. Chapter 2 Experimental 2.1 Ma tenkls

Spirene monomer (99%~~,LW IN, adrich) uihibited wirh 10-15 ppm Ctert-butylc~tecliol was dned over calcium hydnde (<>50:0, r\ldrich) ;ind disded under reduced pressure tu remove dit. inhibitor. The styrene was kept dry over activated M moledu sieres (BDH) under a blaiiket d nitrogen. To prevent aiiy themial polymerization, the monomer mas retiiger~ted;uid stored ui die dar k.

Polperizatioiis were carried out under nitrogeii (Liquid (:;trlioiiic, prepurtfied) rhat w:is hderdried by püssing tiirou@i ;i columi of dry 4-A rnoleculilr sieves.

-Re starting materials for the canlyst syritheses were purchÿsed from .ildricli aid wwre used without hrdier puritication. CpbTiC13precunor was obniiied hmn stock supply, preriously svndirsized bv Dr. II--\. Koeslag (lab of ILC. Baird, Queen's Chemistry Dept.) usiiiç liter.inire procedures. .ifter the sviitlieses, the catdysts were stored nid refrlger~red iriside :i \-miiirn

.\trnospheres giovebos.

hlethyl edyl ketone (hlEKJ +andmethmol used in die puritic;itioris were re;igerir g-cide.

q5-Penrmediylylopenndien$tiniiiumrrimethyl (CpBTi.\le,) citd ys t :uid tris (pe~itiifluoropheryl) bom (B(GF5)3) cocatalys t were syithestzed iii-linuse, under puri fied nitropn, usiiig standard Shlenk line tediriiques, a V;lcuum ..\trnospheres glovebos md dned/deon~natedsolvents. 2.2.1 Preparaaon of Cp(TiMe3 Catalys t

The prepÿration of CpWTii\.1e,wÿs moditied from that of .\.letin ;uid Ruya45 2 g of Cp'Ti(:l i

precursor (6.91 rnmol) was dissolved in 80 mL of hexanes ÿnd cooled to -U°C (~cetonitrileslusli).

20.73 mL of rnechyiithium (14.81 mm01 of 1.4 mol/L solution Li etlier) tv:~ïdded dropwise ovrr :i

period of 30 miri to the above sucred solution . The resulaiig suspeiisicin \vas duk green in colour.

.\fier 3 Iirs die slush bath w;is removed md sùrrüig \vas continued. .\fier aiother 7 Iirs the solutiori

wxs tïdtered over Celite and evaporared to dryness urider vacuum. The producr cryscals were d;uk green in colour ruid the yield was approsim;itely 75% (1.18 g). 'H ShCR iridicared iI6.GU'~puri? l~y

inteption *and comparison with the neigliboruig pei. The cacalyst producr wils used widiout

hdier purification and the same batch wüs used t'or dl the po1ymeriz:itÏciris.

IF1 NlCR (ppm in GD6),1.74 (sr 15 H, Cp'), 0.99 (s, ?Fi, Ti-&le)

2.2.2 Preparation of B(GFj)3 Cocatalyst

The prepamtion of S(C>Fj)3 \V;S moditied froni diat of .LI:tisey ;uid P;irk.46 10-0 g of bromopentafluorobenzeiie (5.04 mi,, 40.4 mml) w;is dissolved in 350 mL 1ies;iiies. The soluriciii tvas theri freeze-&;LWdegxssed arid cooied to -78T (isoprc~pariolslusfi) . \K hile s tirriiig the ;ib(n-c solution, 41.5 mm01 of buslithium (35.3 mL of 1.6 mol/L solution iii tiesaiies) wws added dropwisc.

white suspension resulted ;md it was stirred for 2 hours. Nesr, 133 mmol of horai tric1ilc)ridc

(13.3 mL of 1.0 mol /L solution in Iieprane) was ridded dropwise. Tiie reactioii was theri s rirred fijr 1 hr more at -78OC: before rhe slush bath was removed. =\fter stirring 7 hrs hrtlier, wliile dlowirig dit. solution to wam to room temperamre die misture w:is Ieft to sertle for I ' L iirs. nie supcni;iraiit was tïdtered rlirougti Celite imd then evapor~tedtr, dryiess under mxum. The producr c-srds tvcrc brownrsh-white in coIour and a yieId of 47°'o (3.3 g) was obtaiiied. Furtiier piirific~riori\cx ciirricd out bv sublimation under vacuum ;it 8j°C onto water-crloled cold firiger, nie resulrliig B(Ct,F5)3 crystds were white iri colour. 23.1 RIM MMng Apparatus

.UI of the syndiospecific styrene po1yneriz;ltions were carried out widi n miiii RI.\[ apparatus. The RLLl apparatus consisted of a specially consuucred &ss mishr~d a1d ;i pol yxopylene Kenics sntic mixer (Chemineer-Kenics) combination (Fiy re 2.1). The knpingemrrir midie~dhad injection porr bore diameters of 1.4 mm ;uid a 0.50 cm c~vitydWmerer (8 mm, sp dl).

To mesure die effectiveness of the impingement misirig ;ui es timiitioii o Ç rlir Rc yiolds number (Re) was used. .b mentioned in section 1.3.1, Macosko has outlined fhat a vdue of Re > 3Hi provides good impingement rnising for a RIM process based on polyurediaiie cl~emistry.~"-;\ simi1:ir cddation for the sustem, based on 1 ml/s tlowrares, die room ternper.iture deiisity :md viscosi~of srvrene and the iniecrion port diameter resulted in ;i Re of 4 1070 wliich sliouid provide sutticieiir mising. To enhmce the rnising from the impingrneiit sectioii, a 74 elemeiit ii.5 cm OD Kenics n Impingement rl M ixhead

Cocatalys r + + Styreiie

Static Mixer

Note. =@am not to scdc Iiito the AIouId Figure 2.1: RIM Mixhead Schematic satic miser wÿs dso udized. The Kenics mixer design çorisisad of a series of 18U0 nvisred leti handed and cight handed elements digned at 90° to complete die rnising by tlow division, tloiv reversai and radial rni,~i.ng.~'

2.3.2 RIM Technique

.\ typicai polymerization cun was cirried out as follows. .il1 apparatus materials were dd ui a vacuum oven at 60°C before use. The appmtus was assembled as diapmmed in Figpre 7.2.

The mi-shead ports were sded with mbber sepn (8mm OD, .Udricli) and fitred to the Krtiics st:itic miser by PE tubing (l/C' I.D., Fisherbrand). Both the rnisheÿd/sr:iric miser iuid the thrmocouplc were fitted through a rubber septum (20.5 mm, .Udricli) ;md sded iiiside tlic test tube mould (25 s

150 mm, Comuig). .ifter seiiiis the tictings with p;irxfdrn Eipe, the iippa~ituswis rvacu:itrd fiir 1

Iir. .ifter evacuatioii, the apparatus atmosphece was back flled widi iiitroseii :uid ;i coiista~ittlo\v was liept. .hi- escess pressure wvas re1e;lsed dirougii a needle valve looited ar the eiitr.uice to the mould. To proride a consisteiit mould \;il1 remperxure, the dass mouid KLS submerscd iii ;i l:irgc silicone oil biith.

Both die c;itdyst ;uid cocat;ilysc were weighed iuid recrieved from ;i ir;icuum .imosplicrcs giovebos. 1 1 mg of Cp'TiiMe3 msweigiied md seded iii a test nihe witli ii rubber sepn/p:ir~tïdm.

78 mg of B(CbF5), was also weighed ÿnd seded in a test tube wirli ;i rulilier septdpar~filrndong wirli a 1/Y" Tetlon magnetic stir bar. nie srir bar md stir plate were utilized to promore lierter misiiig ot the borme :uid styrerie. PE/PP syringes (10 mL, Forruna) were titred with saiiiless steel iierdles

(PT:, Y, Hamilton) and backfdled wirh S. ùi a separate sealed test tube. Prerir>uslydistilled styeiic was removed from tlie refrigentor and ailowed to wrni to room temperature.

Iri the following order, 2 mL of styreiie was iidded to the Cp'TihIc3 to il~liicvc .i coiiceritratioii of (i.341 AI. Sest, 3.25 d of styerie was added to tlie stirred test nibe of B((:aF;j)> rc J achieve a coizceritr~tionof (1.343 LI. Tll~estn ( 1.25 mL of moriomer \v:is ;iddecl to die B(C,,Fjjs ri, prereiit tlir uptalie of insolul>lest~lids if preseiit. 2 mL of die (:pTi.\lr, solution \v;is t;Lcii up .iid then the needle tip was insened into die rïght seded port of the mishrïd. Sest, oidy 3 rnL of rlie

B(C&)J solution was taken up and insened into the left srded port of die mixhad- Th prep-mtion tirne of the canlyst solutions was esumated to be benvrçn 45-60 seconds. Fidly, borli syringes were simulrmeously depressed slowly -and metered to keep the tlow and impingemerir uniform. The materid could be viewed while flowing through die mislied, formuig a blecli coloured comples md then pÿssuig through the Kenics miser. In die bottom of the mould, rlie polymer plug solidified benveen 13-10 seconds and it was estirnired that the injection proçcss occurred widiin 4 seconds. Due ro the mpid solidificxtion time, ir w;is obsemed tliat up to n ppni of the reacnnt material brcme trapped in the rnishead, mosdy iii die sr~ticmiser. 031 :nVerdgerlie ror:il time for prepmtion -and complere injection into the mould was ;ipprtxirn~tely1 mirute.

RIhI Irnpiugeriierit Sectioti

Stirrcd

B (C.Fs) 2 Cocdyst Solution

Figure 2.2: RIM Apparatus Setup 2.3 3 Temperature Monitoring

.A Est response 1/ 16" type K tliemocouple supplied by Omep Eiigiiieeriiig was posi tioiied precisely in die center of the &ss mould arid elevared slighdy above die botrom. Just prior tu tlir injection of the reaccuit rnaterials, n dan acquisition compter progra.cn was initiared to record dit. temperature *and tirne via rn Omega Enginee~gDP-41 Temperature b [eter.

2.3.4.1 Polymerization of Styrene by Borane Cocatalys t Tc) determine die mount of styrene polynerized by the homie coclrdy duriiig rlic premising step of die borane aiid the sryrene, 36 mg of borarie w:o mised widi 3 mL of styreiic

(NO23 59 at room tempenmre. .Uter 45 seconds, 10 mL of :iciditied merhaiiol w;ü: iiiiected to terminate the pol~erization. Tiie precipinted polymer was then dried in the v:icuum oïeii nid weighed. To determine the mouiir of styrene polymetized :it a Iiigher rempecimre, rlic sunc rmction was wried out using sryreiie preheated tbr 10 miii at l(.)O°C.

2.3.4.2 Benchmark Controt Study

Ili order to est-blish a weU defilied bericf;.n-~rkcondition ;uid ro test die reproducibili' ot the reacrion procedure, four polymerizations were carried out ÿs desctibed nbove widi the sniid:irci cataiyst recipe, room temperature reaccmts and ;i one Iiour reactiori rime. Tlie moriomer çunversioii wru deterr-nined ;is described in 23-51 and the polymer product c1iür;icterizcd as described in 2.4.

The results of these polymerizatioris were statisticall~taliulnted as the bencfim;irk ii~Giisr\vliicli ;dl odier polymerlzatioii coiiditioiis would be compared.

2.3.4.3 Mucing Smdy

Tc> determirie wliedier or iiar die polymerizatioris were misiiig limited, kiur differeiit misirig

ïciiidittons were s tudied. Firstl y, ;i no mlsiiig coiiditiori \GIS memp red in wliich die rc:icr;inrs nwc uijrçred direçdy Uito the glss test tube mould cotinuiing ody the dit.moçouplr. nie secolid KU ii

no sutic miring condition in which the Kenics misiig elemeiits were removed nid the Liipiiigemeiir

rnishead outiet wu: fitted direcdy Lito the mould. The third ÿnd rnarked as the sniidard rnisiiig

condition was the use of the RIIL[ mi-shead and smtic miser cornbuiatioii as outliried in section 3.3.3.

The Isr condition was the use of a Iarger dimeter rni.uhead. .A polypropflene T-ioiiir from Sdgeiir

with larger bore diameten of4 mm on die injection pom uid cavity oudet wxs araclied in place ot

the glass MM misfiead.

23.4.4 Reaction Time Study

To detede the tirne to complete the reÿction, RIM pol~meriz;lrioiiswcre carrird out \r.itli

reaction cime iritewals of 2 min, 10 min, 1 hour, 6 hours smd 34 hours.

23.4.5 Mould Wail Temperature Study

To determinr the effect of mould rempenture on the RI.\.[polyrneriz;itioii, mould \dl

temper~turesabove and below rmm temperature were evdu-ated iii ;i rm~eIrom -X°C tci 1 li IO( :.

Room temperm.tre polymerizations were cvried our in a silicoiie oil txidi as a Iiat tmisfer rncdiiim.

Runs perfomed at elevated temperatures were rhemosr~ticdlycoiitrnlled usirig :i CI:i;Ae D(3

Tempenture Conuoller. For these runs, the mould appÿrxus was pre1ie;ired br ' i Iiour itiside tlic

bath. The ceactants were kept :it room rempenture and nor prelieated, tu prevetir atiy sigiitiç:uir

tliermÿl polymerizauoii of styreiie. Runs perfomed at o°C were çooled usirig a srirred ice-wircr

bath. Bodi the mould and reactvir styrene were cliilled for at lat15 minutes prior tr) the mising of

die catalyst solutioiis and injection into die RIM appmrus. Ruris perfomed ;it ccygtiriic

temperatures were cooled using a temciil«roedi;uie/liquid iiitrogii cold b:itii. Roth the mould :uid reactant screne were dso chilled prior tu die m~sirigof die catdyst solutioiis ;uid irilect~oii~iitrj dit.

RI,\ [ appiintus. 2.3.5.1 Vacuum Oven Drying

To mesure the polyrnerizatioii yield, tiie eritire üpp;ir~nisaid @;fis rnould were wei#tiecl prior to and üfrer the compleced reaction to determine the -mount of polymer iii the iipp;ir.tus ;uid giass mould. To temuiiate die reactioti, the polymer plug was powdered iri a coffee prider. Tlic tirne elapsed brtween weighuig ÿnd grinding of the plugs w-as appmsirnately one minute. .-Ifter powdering, a noticeable coIour chuige from ddgreen/brown to ;i bright orange WJS obsen-ed. signi5hg die climge in the Ti caraiyst osidatioii state. The sample w;is weigtied oii a +pl;ice

S~~OUSbdaiice and the residual monomer wris removed by drying in a vacuum overi at Sii°C untd constant weight vas acfiieved. It was observed diat die dqiiig rime to ;~cliievecorist;uit \veiglir ocmrred benveen 3-4 weeks which is unusudly long when compared to the d~irigof ;ir;ictic polystyrene smples. The cdcuiated residwd monomer loss was then rakeri ;s ai estim;ite of rlic ovecd1 moriomer conversion.

2.3 5.2 Thermogravimetric Anabsis (TGA)

Ta veri. die vacuum oven dqirig merhod, the moriomer weight loss bu TG.-\ nhds ;ho detemüried, using a Metder T-'UOOi:, system with TG30 thermnbdmce. The TG=\ iuidysis W;IS carried out by Iieauiig the smple Çrom 3U°C to JOO°C at 3 me nf lfi°C/miii. The mass loss ;ir 311

OC: was used as ;in indication to the mount of residud monomer lost by die sample. 2.1 CharacteI-izarion of PS Polymers Please refer to Figure 2.3 For ;r flow chan of the ch-mcterization procedure used.

2.4.1 Detemination of SPS/aPS Fractions

During the polytnerirition, both a~icticÿnd syndiotactic polystyrene -are brmed. To derecmine the -mount of syndiorictic and anctic polymer produced, the fractions were separited bp solvent estraction with MEK. A Soshlet estraction apparatus was setup. Ground polymer w;w weiglied ;uid placed inside an estraction diimble and reflused for 48 Iiours. .ifter esrrxtiun. die thirnble wvasdried in the vacuum oven at 60uC and the .LUX insotuble polymer weiglied (SIS). Tlic

XEK solubie polmer (.aPS) \vas precipinted by dissolutiori ui 10 times die solution volume of medianol. The resulrîng polymer wvs chen dried in die vacuum oveii :it 6ii°C and weiglied. Duniig die esrnctioii process, it was caiculated hrthe material losses were arourid 10 '/O. This is belirved to have occurred duriiig the reprecipintion -and tiltentig process for rlic .\ELsoluble polymer.

2.4.2 Product Identification and Tacticity Analysis

The purified aPS and sPS polymer \vas cliÿracterized by ShLR specrroscopy. 1H-SI[R \v:ü performed on a Bniker .kM-700 spectrometer oper~tiiigat 200.137 IMz while the sPS lJ(:-SIIR were obrined on a Bder C\'P-300 miming at 50.306 hLHL . The aPS 13C ShCR spertmm was me;isured ar room temperature in tolune-da while tlie aPS IH, sPS 1H ;uid 13C ?;.\IR were masurrd at 393K in 1,122,-tetrachloroethvie-d,. For che hi& temperature spectri, the s-amples wcrc equilibrited in a he~terblock to dow swelling and dissolution of rlie polymer. To differeiiti:itc benveen die ar~cticimd die syidionctic polymer, 1H NMR peaks iii the 1-3 ppm regai wcrc analyzed. Figure 7.4 depica the CH and CHr proton signais for rlie diree types of poly-yreiies.

Since the CH and CH2protons are split equivalently in the dtenintiris structure of sPS, ;i tripler 1s detected ;it 1.4 ppm instead of a broad resorimce or a multiplet ;is in aPS ;uid iPS resprcrivcly. -nit

O O sytidioraxicin of die polystyreiie \t.ifi detemiriied by 13C ShlR where by tlie plieriyl Cl Polymer plug powdercd in CO fke grinde r 1

Powdered sarnple is Deteminarion of weighed and chen dried 3 Residud Monomer and Conversion in Vacuum Ohen

MEK Insoluble MEK Soluble Polymer Polyrner

sPS Identification aPS Ideriti ficatioii Determination of f- bu 1H ‘i;LCR, "(3 by 'H XMR, 'SC " 'o Syxiiotacticity N &,IR NhDi

sPS hlolecular Wei& t aPS A [olecular Weigh t DetemÜnatiori bu De temination 11y HTGPC HTGP c:

Figure 2.3: Flowchan of the characterization of RIM samples carbon resonmce gdve *an indication to the stereoregulÿnty of die peiinds Li rhr polyrner. Fib~re2.5 shows the Cl phenyl resonmces and a shq singiet at 145.2 ppm corresponds ro the rrrr peiicid configuration while odier pentad combinations are shifred downfield.

Chernical Shi fr (ppm )

Figure 2.4: 1H NMR of methine and Figure 2.5: 2 *C NMR of phenyl C repion melhylene C region of of polystyrenes polystyrenes

2.43 Determination of Thermai Properties

>leIrkg point, dass tmisition and uidothermd crysraiiit~rioiitemperxures were determitietl for the unpurificd -and dried sPS samples in a Metder T.\3OU(.) Differeiiti;il Scumirig Ciilorimtiter.

Two scaiis were performed. The firsr scm was at a heatuig rxe of I(!OC/miri hm3c37(ioC tu ense die themai histocy of the sarnple by the DSC cycle of melting followed by qurrichtii~wrli liquid nitrogen. The second scan was at a heating nte of 10°C/miii from 50-34 )()OCand from tiiis scan, die tempemures were recorded.

2-4.4 Detemination of MoIecular Weight

>hlcmlur weigiirs of the sPS and aBc; materid were meüsured by IiigIi temper.irurc gcl pemcatioii chr«m;itopphy (HTGPQ on ;i \Yaters 150-C GPC ;ir l-lj°C iii rriclilorol~eiizeiieff-(:RI. Solurions of0.l NT-''O sPS polymer ui TCB were prepared aiid bared in a 145 OC: silicone oil biidi ro obnui çomplere visible dissolution of the polymer. This dissolution procedure wÿs necessa? stricr penerration of the TCB was difimit due to the crysnllinity of the sPS samples. ÿDS polymers ui :i

0.1 W. solution were readily soluble in TCB. .i cdibntion cunre coiistructed ushg TSK TOSOH polystyrene standards in a range of 9100 g/mol ro 1,0911,OM) g/mol wu used to esrimire rlic molecular weight and polydispersity index of the sarnple using hkxirna's Baseliiie so fnv'are.

2.4.5 Estimation of sPS Crystallinity and Identification of Crystdline Forms

To estimate the degree of cqsnllinity of the sPS smple, the eiithdpy of meIrin3 \c:ü meüsured iti a .\letder TrUOOO Differentid Scuuiirig Cdocimerer. nie undried polyner siimpie wü scanned at 10°C/min in n range of 5i1°C to 3(10°C. Tlie melting eiidorherm char occurred miund

?7iJ°C \vas ititegxed to estimate the eritlidpy of rneltiiig of the cryst;dliz:ible ponioii of die smple.

This endidpu cornp:md to die enthÿlpy of hsioii of liHl0'o crystdliiie sPS (AH' 53.2 J/pjtn to

esrinwte die "10 ~rydhiityof the sample. Since sPS cm isodiedlv crysrilize, it is possible rli:ir these crysdluiity esrimates are higli, beiiig panid- represetir~tiveof die urigirid :imouiit :uid rlic ctycdlizariori during die DSC heatuig cycle.

To determine die crystalline form produced during the sPS polymerizauori, FI'IR idysis ut;ü carried out on an undried polymer sample. For cornparison, a specrrum was ais» obrairied from n dned md pun tied smpie. nie specm were obraüied €rom a BO,\.E.\ [ .\LR Scries IR instrumeiir III

FT mode with a resolution of 4 cm-'. The sarnple \vas powdered :mi pressed Lienveeri Drdists behre scm~iüigbenveen 400-4UOO cm-'. To ideritifj- die sPS c~srdlincfmn, the sample \\+:fi mdyzed in die regions benveeii ll(.)O-lXlO cm-', 811(.)-lOOiI cm-' ;uid 400-6j0 cm1 :uid tvcrc compared to die lirerature specrra shown in Figure 2.6 depictiiig the differeiices betweeii :unorpla~us.

6-helicd, P-zipg and a-zigzag structural (omis. Specific buids hr identieing the fiirms cnur ;ir 6 ünd y forms and in the -IUT)-63.0 cm-' regiori, p& at SiiO md 570 cm-' cle~rlydepÎct ;L Iiclid structure. The y tom spectnim looks very similiir to the 6 tom escept Los ;i slut't in inrensicies. shifr in 1-xger intensity for the 975 cm-' when compared to 965 cm-' is indicative of the 7 tom ;uid this is shown in Figure 3.8. 1400 1350 lm i2M 1200 150 Wa..nriikr in cm"

Warmrrnkr h cm"

Figure 2.6: Expanded infrared spectra of sPS crystalline forms (Guerra et al.)l (A) 1100-1400 cm-' (B) 860-940 cm-' (C)400-650 cm-' Figure 2.7: FTIR spectra of sPS distinguishing a and P crystalline forms (Guena et al.)'

Wovenurnber in cm-'

Figure 2.8: FTIR spectra of sPS distinguishing 6 and y crystalline forms (Musto et al.)'

4'1 Chapter 3

Results and Discussion 3.0 Results and Discussion

3.1. Estbnathg the Monomer Conversion of BuU- Poi'erized HM Samples

In rn indusuial RL\.[ process, the pam produced ;ire usually demoulded in their fuid use fom. When dealing with a bulk polymerized RLLf s-ample, difficuly ÿnses in estimÿwig die conversion of n solid polymer plug since quick termination of the rwcrion ÿrid accurmare remo~idof the residud monomer is important. Dunng the re~ctioii,it was observed diat the polymeriziiig rnisture wodd se1 ÿnd solidifv widiin 13-30 secoiids. .-\fter 2 miiiutes. die resultiiig pdyner plug 1~:~s liard and dmost d~ to the touch. Tliis npid solidifie-~tion çmses diffi~ultyin estimihiig dit. conversion. h[osr methods to estimate the conversion require thar the sample Lie dissolved in solution. -4s mentioned previously, sPS has escellent solmnt resistmçe. sPS will on1 y dissolve ;it higli temperature in a few selective solvents such is uichiorobeiizene and tolueiie. Tlie usc of :i solvenr ÿr high temperature to dissolve the polyner was considered but at the +10i.l0C tempecirures required. died polymerlzition of die residud sryreiie would occur whicii would rcsulr tii higticr polymer yields from the additional atactic polymer. ;\nother disadcuit~geof usiiig a precipir~tioii method would be €rom the normal ilmaterial losses iricurred duririg die rniuiiid m;uiipul;itiori ;uid tilteriiig of tlie smple. If the residual styrene monomer was erduated by a clir~imto~~:ipli~ mediod, the sme themai polymenzation coiicems would be ~didbur more pmblemïtiç would be the dissolution of the sPS polymer ui the curreiit chromatopphic solverits in use. TIius rlic methods of dissolutioii ;uid precipintion and p/liquid chromatog,ipliy were nor used ro rstirn;irr the conversion.

For metdlocene solution polymerizatioiis, die addiriori of acidified meth;uiol will sufficieiitly

Ml dl the active catalytic sites by coordination with the ;icid iuid idcolml goups. 1ietli;riir)I iidditioii also aids in die precipicition and separation of die polyrner from the escess m«iiomer/solrrnt. For die ilIII plug. the use of a queiicliing solreiit w;is deemed uiifeÿsilile silice tlie high miirersioiis Itxi ni :i solid polymer plus widi ;L 7.5 cm di:merer. Diftiision iuid peiiercitioii of :L solïriir iiiro rliis solid plug would be very slow md result in pooc tetmiiatioii of the reÿctiori. .-\ more feadie medicd oi termination was by grinding the polymer plug uito powder usirig n converitionii cdfee

Cnfominatelr, during this process the shape of die moulded polyrner was lost but by esposing rhe grearer mount of surface ara the catalyst was deactivated by the oygen/moisnire nmosphere. This canlyst deactivation was noted by the change in osidation snte of die residud Ti caralyst ui die polymer From 3 Ti(l1I) dark green colour to a bright orange. At rhis sqe, the addition of licidifird methmol was considered but it was felt that any esm sample rnanipul;itioii would wli ;~wiywmc of die residual monomer -and hinder the accume weighing of die smple.

To quiclily md effectively remove the residud styrene monomer, ciiily ri remperimre nbovc the polyscyrene Tg ar 110 OC would provide die mobility of the polymec c1i;iii.i~ CO -dow dit. udiindered diffusion of the moriomer fiom the ;morphous regioris. Cnfornrriately, at 1IOOC, thc rate of styrene themal polymerizatioii would become signifiant, so iiiste;id, die polymer w;is dd below die Tg in a vamum oven. .-Uthou$ the Tg tms unaffected bu the wmum pressure, rlie ev;ipor~tioiiof the moiiorner vas considembly erihaiiced suice die styene vapour pressure escceds die vacuum pressure (30 iniig below atmospheric) ;it a temperature of 33.(J°CJ9 To 1xil:uice tlic effect of die reduced monomer mobility below d-ie Tg md tiie diemd po1yneriz;itioti of residiid styrene, die polymer powder was dried nt BO0C so as to be liigli ericiugli hr difishi rri occur btir low enough for the rate of themid polymerizatiori to be low. As meiitioiied 1n section 23-51, rlic srunples took 3-4 weeks to reacli a consrnt weight. Duruig diis lerigdiy period, it w;is h~uridtli~t mosr of die residual styrene was removed within the first ~~vohoufi ;uid oiily smdl weiglir losscs resulted aftenvards. If the me of thermal polymerizatioti w;is sigiificiuit, it would be espected thrit die coiistmt weight loss would be acliieved more quickly. Looking ;tt the mech;u~ismfor styreiic themil polynerization as outlined in section 1.7.1, it is possible tli;it the preseiice of residd Ti catdyst prevented die formation of styrerie cadicals by binding to thern -as the? were frmned.

-Uthougii tiie Ti catdyst is preserit in very smdl quantiries, tliis mecli;uiism mil? he sufficieiit ro prevent low rates of themxd polynecintion. If this were me, tliis would esplain why :i shortcr dqing penod for the residual monomer removal was not observed.

-4s mentioned previously, it would have been desinble to obmin a conversion esrimm of the enrire polymer sample. Uniomnately, rhis wu not possible since material wÿs often a-pped in rhe Rh[ mising apparatus and lost du~gthe gniiding process. It was also iiecessary to sa\*e scimr of the widried polymer for hriher -mdysis. To estimate die conversion r>f the polymer, "a relative calculacion" was used. The O4o residual monomer removed dutitig die dqirig of a test portion \vas considered represenr~tiveof the eritire polyner sample produced. The ''0 polymer cernaking atier die residud moriomer was removed was then takeii -as the conversiori estimate under die mumpttori diat the sample was Iiomogeneous.

To verle the method of vacuum oven dryiiig, themuFivimetric ;ui;tiysis W-JS carned out ro determine die weiglit loss of the simple durüig a temperature tise of 1(,OC/miri. Duriiig rliis he:iriiig procrss, a monorner evapor~tionpeak was detected benveeii 14~-15i)~C:and a polymer deg-~id;irioti

prk ÿrouiid -IIii°C. Please rehr to .-\ppendis .A €or the TG.\ tliermowm. Tlie ("O siimple wei~lir remaining after the weight loss sr~bilized(arourid 3(HJ0q was nkeii iis the estimate of die startiiig mas of the smple that h;id polymecized. The conversion estim~test'rom die vacuum oven dqiiig

-md TG.\ W. loss frorn nvo of the samples are showii ui Table 3.1:

Conversion Estimation ,Lietliod

(Ca: ssOc) (@; 31 ioOq I -A (BhI #3) 78.2 9'0 82.1 "/O ---- B (3 min #2) 78.8 ?O #J.I?'O -- - TabIe 3.1: Cornparison of Conversion Estimates for Vacuum Oven Drying and TGA Wt. Loss

On cornparisoii of the vacuum oveii d+g and die TC;..\ weidit loss From smples .A K. R, the TCi.4 conversion estimites were higher dian the vacuum oven estimaccs. -Udiough it is difficult to ;ir91t. th;it these results are physiciilly differeiit, die diffemice rnq be ui die measuremeiir irself. In the

TG:\ rneiisuremeiit, milliLgramsmple w-eiglits were uscd wliicli m;iy iiot hiive becri rcpreseiitritivc O t rlie ~4ioles;unple. \Yhile lie:itirig ;ir ;i lU°C/rniii cite, tliemd p~l~mc~i~:iti~tir)f syrciie m:iy ti:ivc ocmrred at the Iiigher temperitures, at a gredter nte tlmi die caraiyric buiding mecliuiism rneiitioiicd

previously. This extra polymecizaaon wouid account for the Iiigtier conversioii estirnates hmrtie

TG-\ measurements. Regardless of the small ciifferences, both mediods contirmed thar arowid 2iIU.

residual monomer was present in the ~ndnedsmples and thar bodi conversion estimrioii

techniques ue üi general agreement and consistent wirh previous srudie~.~'

3.2.1 Benchmark Reproducibility

One of the important objectives in cquig out this study wrs tr) esr~biish2 well-defiiicd polyneriz~tionprocedure chat would provide reproducible results. In dediiig with die ;Gr-seiisirivc. organometdlic compounds, reproducibiliry ws ;rl\v~ysa conceni. The ç;it;dytic xtivity of dirse cornpounds cm vary depending on die ÿmount of impurities iii;idvertetitly ;ilIowed iiito die systern.

These impurities cm be linhd to a iiwnber of sources, such as isx?geii/moisnire coiiretir in dic amosplirre, idsorbed moismre on the giÿsswxe and tiiuidliiig aiid t~uisfertechniques of the c~ilyst miiterids ;ind moiiomer.

Some of the reproducible ch-aracteristics of the rextioii were ol)sened quiiiicirively. Duriris the initiai sr;iges of die reaction, observations of the npid solidifimticiii ;uid hish remperdrure riscs; were utdized as criteria for reproducibility. -\ s~milarremark from Baird et ;il., menrioricd tliar

"ri~orousexclusion of moismre \vas iircessq for npid aiid reprodiicible polymerizatioii ro hi@ moleculÿr weiglit product to occuri'.i 1t \slater nohced rhat lower temperdture rises utcf slower solidification times riften dtered the balance of syndiotactic/at;ictic polymer ciusing a decrezise in rlir s yndiotactic fmctioii while some times, but iio t dwys, affectirig the overall convers ioti. .-\ tq~icd tempemture rise versus tirne curve is showii in Figure 3.1. Ir c;m be seeii tliat ;L 1(1-3 1 secoiid induction period ws eshibited during the formation of the iictive comples. .iftenvards a cipid tempecinire rise wis obsemed widi the peak temperature occurriii~;ifter 1 minute. This r.~pid remperdcure rise, dthough similar to a 'iorrish-Trwnsdorff gel effect is probalil- not dur ro .l reduction in the tennination rate since coordination polymerizatioiis Iiwe 110 defiitive terminauon mechiuiisrns unlike free radical polymerizations. Instead this rapid tempenture cise I: artributeci ro the acceleration of die reaction rJte as the rempenture of the reaction rnisnire incrrrses. Mrer die peak tempenrure, the reaction temperature dropped npidly back to the initial silicone barh remperanire after 10 minutes. This tempenture profile was faidy reprt~duçibleui most of the rmm remperanire polymerizations perfomed.

Figure 3.1: Typical sPS EUM polyrnerization reactioo temperature profile

It was noted in section 3.3.3 that m estra mising srep wis used tci dissolve die brxuic cocanlyst in the styrene monomec. From previous especience, it ws tbuiid rliar die solubili- of rlic bo~uiein sFreIie was lower thaii thüt of the Cp*Tii\.Iescanlyst. It was ofrcii iioticed tliat ii porti(ni of die bomie was irisoluble in die styreiie, often tormirig ;r solid residue covcred Li? ;i slii~iy trmsparent laor. This sliiny 1-r was spedated to be a thin Iayer of aracuc polystyrerie wliicli formed ÿround the boraie preventlig ia full dissolutioii. Ir was diffinilt to boorh qu:iriri& atal reproduce die amount of insoluble borne. This residue was also believed to have dtered the 1:1 caralyst:cocadysr concentration ratio. It \vas evenniÿlly dkcovered fhat by stirring die rnisrure, complete visible dissolution of the borane could be achieved .and rhis misirig ÿided in die cacd:;sr ratio belng mainnined.

-\f'er much pnctice, the recliiiique for the RIM poIp~e~i~:itioiiof sPS wi esrablislied s describrd in section 2.3.1, allowing the procedures for the material hÿridliiig and timing ro be rouriiie.

Cpon esr~blishliga systematic mutine, variability in funire mesuremelits could oidy be artribureci ru inherent variiitioii. To define the benchmrk reproducibility =id to minimize viy system~tiçrrrors due io impuriq buildup, the esperïmenrai mn order w;ls raidornized. nie hl1 esperimrnïd run Iisr is sliown in .-\ppeiidis B. .G; sliown, the four standard beii~hrnii~kmiis were çîrrird oiir periodically benveen eacii pmeter investigared. niese srmd;ird ruris were carried oiir :ir rrxm temperature with ii one hour reaction rime, utilizing the standard RIhf misiiig app'xdrus. A summ;i~ of die resuits is showri in Table 3.2. It was faund for die Çmr po1yrneriz:itioiis tliar the tempecinire peak \vas brnveeii 118-l26OC and die mesurdbie poiyrner yield in the mould wù. benverii 2-1-25g-

Tiie averdge residual monomer loss ww 23.9 + 1.3 which correspoiids to 70.1 2 1.3 O8t, coii\wsron both at a 95O.o confideiice level witli 3 degrees of freedom (DOF). Pleae note char ;dl nther reporred confidence intenrds are dso ;it the 951'0 Icvel. Giveii die diftïndties in controIliiig rlic polymerizations in the pst, tliis levei of reproducibility was surprisingiy good ÿrid accepted ÿs dic srandard benchmark condition.

I Run Description Peak Temp. Rise Polymer Residud Lloiiomer Polymer ec> Yield (g) (4.0) (loiiversiori (4'0)

- - BAI. #3 136 3.35 33.6 76.4 ------, kB:~I. #3 2 26 - 3.18 21.8 78.3 , B.AL #4 133 3.11 24.5 75.5 , .iverage 133 3.39 23.9 + 1.3 76.1 i 1.3 Sote: Conficleuce uitcrrds are rcported rit thc 95"h let-et witli 3 DOF.

Table 3.2: sPS RIM Benchmark Conversion Reproducibility 3.2.2 Characteristics of RIM Polystyrene

To esnblish the reproducibility of the RIh[ sPS polymerizntion with respect to the polymrr properties, the benchmark samples were chancterized For their composition, meltirig poinr, stereore&;uity ;uid molecuiar weighr. Please refer to Table 3.3 for a sumrnary of the polycr

Run sPS Mjusted sPS Weight aPS Weiglir .\.le1 ting sPS Description Fraction aPS Ag. V ;\vg .ILV Point Tüctici~1 Fnctiori" (s l0i g/mol) (s IUJg/mol) (O/O) e(3) (?'O) (?'O) PDrJ FDrl B.M. #1 65.0 30.3 136 '4.01 38 [3.7 BAI. #3 63.8 73.8 167 '3.3: 16 L5.01 267.5 99+

B.11. #3 59.5 26.4 104 4-2; 8-3 :4-T ---- BAL #4 67.3 18.1 1OU '3 .4] 9.9 >.Cl-- 266 ------4 1 .\venge' 63.7k3.G 31-9k3.9 f27t25 16 + 7.4 I 'lote: ' Coofldence intervals are qorted at clie 9j0/1itevel witli 3 DOF. " ."idjusteci ai's t'nctiou cxcludlig die a~uountof aPS polynierized in die pmt~Lskigsteps.

Table 3.3: sPS MM Benchmark Poiymer Properties

--\s described in section 3.4.1, the fiaction ofiitactic md syndiotactic pcilymer wssep;ir~rcd by extraction with XEK solvent. .-\fier 48 hrs of estnctioii, it was fo~uiddiar tlie four beiiclirmrk mns liad ;in average s~ndiotncticfc~criori of 63.7 + 2.6 O,h. Tliis result w;is surprtsingly low wlieri compved to the toluene solution polymecizatioris reported in the litrr~mre\vliich h:we syndior;icric frxtioiis beiiig quite Iiigh in the <)OO/o raige.3." I t was kiiowi Lie forelund rliît prepc>lymerizïtir)ri of the styreiie by die borane would occur. It was observed during the misiiig prcicedure hr die dissolution and injection of die borne that the solution medup uid a norice;ible iricrcase iii viscosity occurred durlig tlie 45 second premisiiig rime. To determilie die ÿmount prepolymerizütioii occiirritig nvo sepfilte polymeciziltion trials of the 11or.uie oiily, ;it :i simil:ir concenrntiori aiid simiiar tirne were carried out at room rempenture vid llO°C. This esperimenr 1s described in section 3.3.4.1 ;uid the resuln are showii iii .\ppeiidis (3. -Afrer temiiriatioii of rlic raicrion widi açidified mediaiiol mid precipitation of die polymer, it WIS huiid tliat 22'; of Ion- moleculi~weight atactic polystyene was fonned under hoth coiiditioiis. This wis considercd ilri estirnate of the iunounr of prepr)lymcriz;itiori th;it takes place duriiig tiic niisiiig stcp. 1 f rhc ;IL~CTIC fr~ctioncdcdaced €rom the % syndiotxtic polyner estraction is adjusted ti~rrhis 32"'~ :ir:içrii prepolyrnecization, the auctic fraction during the polymecization, iiveclged 21.9 I3.9 This adjusment of die atactic fiction was calculated based on the dssumption that the bomie solution conuined 72% amtic polymer and was being mixed wirh die Cp0TiiLle3 portion coiitaiiiiiig titi polymer. This adidjusted anctic fraction 1s sdsignificandy higher tlim the dues repocted in die lirerature possibly due to the use of bulk styrene monomer md uiclusiori of the bomie in die polymerizing :ir~cticpolysryrene backbone. GPC ;uialysis of the ar~cticfrxtiction did axtftrm th:it 1i1w moleculÿr weight aPS w;is being Çormed benveeti 10,0O0-30,IKiO g/mol whicli is consistelit widi die lirerature." As for the moledar weights of the purified sPS, it wÿs derermiiied thar the benclim:irk weiglir avemge rnolecular weight was 127,UOO I?5fl(JO g/mol. The mo1ecul;ir weight disrnburion was dso found ro be brmd, with a polydispersity ùides of around 3.7. It musr L>e noted rli:ir tliis polydispersi- index ma! be slightly Iiigh ssiiice the HTGPC cdibnBoii sri~idd~dsesliibitrd polydispenities of 1.3-1.5 as opposed to being monodispened. Sriil this resulr suggests diÿr tlie catdysr acrivity k v.qing rausing a broadenuig of die molecul:ir wriglit. This bm;ideiiiiig of rlic rnolecular weiglit is unreported for a Cp' system and ma! be die resuit ut' polymer chains 1)eirig formed a&different rempentures during the reaction. Chien3 sugpsred for ;i (IQT~(O(IIH?),/~[..\() sustem, the equilibrium sute of the cadytic species is dso dtered 1)y tempecimre. Bodi rlirse esplaiiarioris are applicable ro this study's observation since the pal< temperxure esperirnced by die active cataiyst species was quite higfi.

To identi- tlie polymer fr~ctioiis,1H XMR specrroscopy did conficm rli:it exli of rlie hctions were sPS and aPS polymer respectively. The specu- for 'Fi ShIR and 1JC SMR üre stiowti in Appendis D. From die 13C NMR the stereoregulari~of the polyers was ;issessed. Tlie rrrr pentad distribution from the 13C specm for the sPS samples esliibited a siiigiet peak zr 145.1 ppm. which c:ui Iie interpreted ;is being esseiitidly 99+"0 sydiot;ictic. This Iiigli srereospecifici~has ;hi been reported bu otliers for a Cp9Ti.\fc3systern.~~ For comparisoti, rhe aracric frxriori eshibircd

:i broad peak iii the 145-146 ppm mis -as sliown in the ti

-\ppendis E. Other chancteristic thermal features identified by DSC were die Tg benveen 85-lIo0(: md the cold crysdization peÿli at 15S°C. Only when the samples were lie~tedto 37U0C: on die tirsr scan to disorder the chains and eme the crystaliinity were these htures observed. The Tg sk-* observed by the midpolit in the cl~mgeui slope md the cold crys~~lizatioripeak bu the preseiice i>t

;iri esotliermic peA. The observed value of the Tg is much lower thari the espected Tg of 10f1°C fiir high molecuiar weight polystyrene. However, the result is representative of ;i dried sarnple coiiniiiiiig a Iqge fr~ctionof low molecular weight ar~cticpolystyreiie wiiicli c;ui sigiificmtIy Iower the Tg Tlie effect of moieailai weiglit on die Tg h:~been do~xrneritedby SperliiiSjo and ;i predicted Tg of No(: cm be cdculated for die low molecu1.x weight polystyrei~e.The cold cryscdlizatioii pe;k ;it ISSOc: was dso losver diai the reported t6U°C: mzyirnum crystallizatsori r.ire pe-A.' Tliis loweritig cit rlic cold crysrdization peak h;is dso been reporred in the Iiter~turefor ;iPS/sPS tilei~ds. This reducriori in temperature lias beeri espiained by die iriterfererice of die nr~cticpol ?mer in die sPS crystiil1iz;iriori prricess, c;tusuig die fomatiori of less perfect crystais by w.üy of disordering the lamellae srackiig III the interfibdlar regions.51

Ir has been demonstr~ted that the RI&[ benchmrk polymerizatioris were statisticdly reproducible, bodi related to die conversioii aid properties of die polymer. This dlows die othcr reaction conditions to be compared to diese benchmarks to determilie viy sigiiificaiit effects. 3.3 Effectof mgon the HM PoI'erZzaaon

33.1 Effect of MWng on Conversion

To evaluate the effecr of mising on the coiivenion four difirent mising conditions wre jtudied ÿnd the esperirnental dard are shonn in Appendis F. Two esuerne cases were considered: die test mbe miUng condition without the RLCL mideaci/static miser ml);md with die sraidard

Ri.\[ mi-she~d/snticmixer condition (BhO. To evaluate the effectiveiiess of rlie RI,\.[ impuigememriir midielid, nins were dso perfomed without the Kenics sntic miser (XS?d) ;uid widi il lïrger dixmeter impin~erneiirmishead (LDM). The effects of die four different mising co~iditîoiison rhr monomer mnversioii levels ïre sliown in FiLgure 3.3.1. To genente die s~itisticderror bars ;it Y 03"' confidence intend, n pooled standard deviation was employed. -4s sreii from rhr rut1 list, 3 rep1ic;ire niiis using no sntic miser and 2 replicate mis usuig a kuger dimeter mislimd wrre airrird mir.

These results coupled with the 4 benchmark runs wvere pooled to obtxiii ;ui esrimare of the sr:uid;ird

Mixux Metliod

Figure 3.3.1: Effect of rnixiag method on the moaomer conversion deviation with 6 degrees of Çreedorn, which resulred Li ;i confidence iiiten-d of & 1.2 "'o. .L- srcii from the gridph, no significant effect of the mixiiig method on the conversion could be seeii for die test tube mising, no satic miUiig and standard mising conditions. However, for die larger dimeter rnising, a slight elfect wu observed. The conversion average for the Iqer diameter rnising wi:w

78.Y0;o while the other chree conditions avenged ody 75.5%. W3.h the exception of die I.xsr dtarneter run, the results indicate tliat under these conditions die RIh[ reactiori is iiot mishg Iimired.

TIirse resuln imply diat even rest tube mising is sufficient uid if the impuigemeiir rnidicid is used. the sntic miser is not required. The observation of the incresed conversion with the larger dcimetrr misbig mybe suggescing die hpomce of aiiodier facror. The iiicrease iii conversioii mÿ- bc espliiined b y the Licreased interf~cialcontact that occurs withii the impiiigemeiit zone. ;U thougli the Reynolds number dculated for this larger diÿmeter rnisheÿd is oiily 375, the results show iniprovernenr. For polyurethaiie systems this lower Re sliodd Lie less efficient in mising bur as previously rnenüoiied, mising in a coordination polymerizatiori sysrem should be sirnpler diui ;L step polymerization in which perfecr stoichiometric balance is not required."~ Tlirrefore, rhe conversiori incrase might be the result of the Ixgr interficiai mi. K'ith a laser ;ue;i, ;i m;iryui;d incrase in the mising rate may have occurred due ro the lower pressure buiId up in clle tmpiiigemeiit mlshead :uid die greater uiterhcial uea. -4ithougii this iiicrease in conversiori is iiclt great, it miy imply ththe rate ofmising is important iind should be studied in the füture.

3.3.2 Effect of Mixing on Material Properties

The effect of rnising on die compositiori of the RIh[ made sPS polper \vas deteimmed by estrdction of the fractions in hEK solvenr. The average sPS fmctioris for the four differeiit misiiiç conditions tire showti in Figure 3.3.3. It cmbe seeii diat no sigiiificaiir differerice in die baiaice of syndiomctic to aucric pol ymer occurred. \Ili rhin the 93"' con fidence lirni ts crimpu ted and using the siune pooliiig scheme of rhe smd;ird deviations ;fi in the above conversion estimates, the avemgt' sPS fraction w:is 63.1 k 3.5 'O wlieii comp;ired to die heiichmark ;ivecigc of 63.7 + 3.S"~o. Duc rr Figure 33.2: Effect of mixing method on the sPS fiaction the equivdency of the sPS hctions, it suggests that the polymerization proceeds bu die same mechanism for di these niris. Therefore, it was assumed rhat the stereoreigularity, thermal properties and mo1ecd;ir weights would be sdarto the benchmark ruris.

3.4 Effectof Reaction Theon the MM Polymerization

3.4.1 Effect of Reaction Time on Conversion

In .an attempt to esnblisti the cime required to complere die palyrneriz;itiori, reaction tirnes were studied behveen 2 min .md 24 hs. For il RIhI process, short demouldirig times are desired. theretore it was of great iriterest to estimate the conversion at 3 minutes. To investigate chedier longer polymerizitioli tirnes were required Cor higjier cnnversions, polymerization tirnes of 10 min, 1 hr, O hrs vid 21 hrs were also studied. The results €rom the reactiori rime smdv ;ire nbuiated 111 -4ppendis G and the rffect of reaction time on die convenioii is shown in Figpre 3.4.1. From die niii list, it cm be seen thar replicate cuns ar 2 min, 10 mui yid 24 hn were included so ÿs to masure the reproducibility. These results combined with the benchmvk runs aiiowed a pooled stmd~d deviaaon to be calculated with 6 degrees of freedom. This pooled srandard deviation ws used to report the O.9% error bar for the convenions at a 95% confidence interval. .As espected, longer reaction cimes resulted in lower residual monomer levels and Iiigher conversions. -At the 6 hr ÿiid 24

Iir re~ctionhs, conversions around 81% were achieved and ÿre sigiificmdy higher thÿii die 1 hr benchmark conversions of 76.1°/o. For die 10 min reaction tirne, the conversion averdge wül; mund

76Wu mhgit no different thm the 1 hr reactions. However, die 1 min reactions resulted iii conversions liiglier thai the Il) min and 1 hr reactioos. The average conversion wÿs 78.5O,'o for die 3 min reaction tirries. Intuitively, ÿny attempts to terminate the reaction ilt shoner times sliould result in either an equivdent or lower coiiversioii &-an the longer tirnes. This result 1i.z replicarcd and

Figure 3.4.1: Effect of reaction time on the monomer conversion vecitied aid inderd it does not foIlow the giierd uerid. This led ro sprrulatkm reprdiiig die ttnic penod at which the termination \vas curied out. ;Ifter diis 2 mit1 rmtiun period, die temprrxure of the mixture wÿs sdl above 100°C uidic~thgdie misture was still iii a II$II~ active snte. The prernature termination of the poiymerization in this active state m:iy have ciused diis rnic~~dous higher conversion ÿnd \\di be further addressed below in the polymer properties. ;\side from ths aiiomalous resulr, it wÿs obsenred that uith iiicrezsing reacrion rime, the conversioii reaches ;i masirnum afier 6 hours and plateilus.

3.4.2 Effect of Reaction Time on Material Properties

The effect of re;iccioii time on the polymer compositioii ~~CI.Sderrrmined by the rstr~srioiiof the fractions in .\.ELsolveiit. The :iverAge sPS fractions produced at the differerit re;lcuoii urnes :ire shown in Fi~wre3.42. To genenire die sarisric;il errnr barj, the replicxte miis ar 2 min :uid die benclimuk niils were pooled togdier to estirrute the sraiid;ud deviatioii. Sote tliis is differeiir thi

Figure 3.42: Effect of reaction time on the sPS fraction the pooling scheme used ro determine the error bars for the conversion study. It \vas fourid dix die

replicares for die 10 min and 24 hr runs were different by 10°,'O. These replicare runs were cïrried

out, ourside of the especimentd om list, du~gai eadier polymerizatioci smdy. Ir was obsewed di:ir

die peak rempentures were ais0 significmdy lower, indiclring a higher level of impurity. Sinçe rile

mns were carried outside of the esperimentd ru11 list, it was felr rhat it was justitied not ro uicludr

these resuits in the matecial properties aialysis. Even though the sPS fr~cuoiisof these runs wre

not consistent widi the otliea, ir is interesring that the correspondhg conversions were in good

agreemen t.

Froni die plot of sPS fiaction venus rime, it was observed rliar the sytidior~cricfrmioti of

polymer produced at the differerit teaction times rernained hrlv coiisrmt ÿrouxid 63"!o widi die

esception of the 2 minute run. These results demonstrate that rhe sy~diospeçiticpolynerizarioii

meciianism cm continue tor longer pol!merization rimes to produçe hi~lierconvenions. How\-er.

ar 2 minutes the syndiotactic fraction was significmdy lower than the rest ar a value of 52 "II. -1s

mentioned previously, die conversion ar diis rextïon time wis dso higlier diai die longer oiirs. Tlie

et'tecr of o?-gen/moisture -md dieir side reactioiis on die catdyst activity hÿs iiot beeri well

documented. .it 7 minutes the reaction \VLS still in a srate of hi& açtiviv. 1t is possible that rlir

prernÿture terrnuintioli of tlie rextioii might have cawed the aiiody iii the "O coiiversioii :uid die

sPS fraction. Esposure ofa reactiiig systern to the armosphere would ;iccouiir for the grmter anctiç

portion of che polymer but cannot account for the greater coiivenioii. The ody plausible

esplmation mny be due to die cooling of the plug upon esposure to tlie atmospliere rhüt may 1i:ivc

çaused the ht&er conversion. The effec; of temperature wdl be esplored in tlie nest section tri clic

mould dltemperature study.

The effect of reiction cime on the mo1ecul.x weighrs of the polymers wts deteminrd II?

GPC. The W. avg. molecular weights of the syndionctic polymer ;it cirying re:icti«n times arc shown in Figure 3.4.3. .4ltliough the GPC results were quite scattered with a hrge emlr bar ~uig 0.0 1 0. 1 1 11) L!JlJ Tune Figure 3.43: Effect of reacaon times on sPS wt avg. molecular weight

4 31,C)OU g/mol, it crui still be seen that widi longer reictioii times an increiise iri molecular weiglir occurs. The molecular weiglit of die sPS polymer after 6 hrs ürrer~~ed175,iiO(.l g/mol, wliicli is higher thm the shorter reiictioii urne molecul-ar weight ;iverage of 1311,000 g/mol. -ildiougii, gveri the ovedap of the error bars, it is possible that the differerice olisen-ed is rioc as 1-qeiis uidictited.

These observations are simiiar ro Cmpbell's ui diat Iiigiier conversioiis ,are ;ictiieved with longer reaction times but different since theu did not observe the a time depeiidency of die molecu1;ir weight-18 TO explore the time depeiidericy of the rnolecular weight tùrther, a plot of die iiumbcr averxge moleadar weight 1's time is shown in Figure 3.4.4. It cm be seeii hmtliis plot dut diere 1s no significmt effecr of the reactioii rime on the number average molecul;ir weight. This lildicatcs chat the rnolecul;~weidit distribution is beitig skewed due to die presence of some tiigl~ermolecu1;ir weigfit specics. It is possible during the loiiger reaction tirnes thsome of the ch;iins xc polymerizing to high molecular weigtit wliich increases die W. avg molecular weiglit. ll{)rr trnport'mtly, tliese results demoristrxte diiit irideed the cadyst rem;iins ;ictivc :is opposed to tmng Figure 3.4.4: Effect of reaction rime on the sPS num, avg. molecular weight deaccivared ;ifter passing through the peak temperarure of I?O°C. GPC aridysis of die at;tct~c hcuoris of pol -mer reveded rhat low moleculÿr weiglit polymer still iii die range of 1OJJOO - 3 1,i li 1 g/mol \vas formed. .it the longer reacàon times no significmt moleodar weight uiçrr~srIII rlie mctic fnction of pol-mer detecred. ;Uthou@i it midit be espected diar die acictic frxrioii would increase dso, it is possible that rhe syndiotactic reaction mecliÿiiism dorniii:ites ar longer rinies.

During the initial mising period, in a bulk conditioii, activation and initiation of die cmlyst cornples is occurrinp, very npidly ;rnd uider highly esothermic conditions. nie eveiits duriiig diis tiinc penod are unlikely to be controllable or uni form but once the tempemure Iiï~snbilized a uni hmi mechanism ci continue. .b for the stereorecgulariry ,and rnelting point, it was ssumed diiit rio significant change in mechanism would occur at sliorter and longer reactir~iitimes, tlierehm, rlic mei ring point and stereoregulari~ would be sirniIar to the benchmark crmdirioris. 3.5 Effect of Mould WdTemperature on die RIM Poiymeniation

3.5.1 Effect of Mould Wafi Temperature on the Monomer Conversion

Temperature control of bdlc polymecizatioti reactors ui iiidusq is quite difficult. -ij

menuoned previously large refiigention uùts are required ro prevent mpid temperature rises aid

thermal mnaway. The exothermic characteristics of this bulk polymerilstiori dso presented quire ;i

problcm in controlling the reactiori ternpenmre. Given the shape of die polymer plugs that werc

hrmed, heat transfer limitations wodd be imposed due to the smdl surfice to volume r~tio.Tlic

heat remov;d from the reactiori woutd be difficult due to diis smdl surfi~ceto volume mtio aid clic

poor heat trais hr cli;rr.icteristics of the glÿ~smould. .ifter tes tiiig mÿiiy dl ffereiit hcit tcuis fer

mediums it was Courid tint acliievùlg isothemal reactioii conditions wnuld be veq di ffiml t ivitiic~ut :i

higidy speci.dized apparxus.

.iiiotlier ctidlenge in conuolliiig the ceaction temperature w3s ro preveiit ai! escess t1ienri;d

po1ymeriz:uioii. Cooling and misiiig the reactarirs ;uourid arid below room tempeclture postid iio

diffimlties sirice die rare of diemai polymerizatiaii would be tiegiigible. Howcver ;ir higlirr

temper-mres, t1ierrn;il po1ymertz;ition ivould occmr. Due to die difficulties in Iie;it remrn.;il du ri ri^ rlir

polymerizauori ;ind to prevent the additional themai polymerizatioti to ara& polystyrene, tlic

decision was made to control .and study the effect of the mould wall temperdture =id not the iriiud

reacrm t tempe rature.

To determine the efFect of mould wdl tempemture on die sPS RI>[ polymerizmori.

reactions were mried out in a mould wdl tempecixure mise benveeii -6 id1 1O0. Tlie motivation beliirid usuig higher temperature moulds wm to iiicre;ise die prilymer cliriiii moMiry above the system Tg and hence reduce ;uiy dif'sioti limiutioiis of the moriomer. :Vtliou~Ii iiicreasing die temperature would Ùicrease the monomer mobility, it \vas dsn kiiriwii chat d~miv;it~on of die catdyst would ;ils0 occur more re;idily.l8J'J= For the higher modd w;dl tempermms. rtic reacting plug temper;iture profiles are stiowti in Fi,gures 3-51 nid 3-52 Frcim these gaplis, ir c;ui t~r. secri tliat die reactioii misture aurpssed tlie mr)iiId ternpermirc wvitliiii 1-5 serrotids, wvtiicli tiidrc;ircs ro dl intenrj and purposes that the temperature differeiice betweeii die initid rmctüiit tempcrdrure and the mould wall was negiigible. During the RLLI benchmark rextiotis, a npid tempennire rÏsç occurred to 12U°C, which may have caused signiticant cadyst deactivation ro occur. nie peik rempenture nse for die 60°C: rnould reaction reached 130°C ïnd the 1 lU°C rr~ctionsreached 13u0(: and 140°C whiie returning to the initial bath temper~niresafter 10 minutes. In lui ïnempt to reducc the peÿli temperature lower mouid rempentures were artempred ui hopes of proloriguig die cadysr icririty. For the O°C and -20°C reactions it wÿs observed that the prik temperxure achirred \cw mlv lowered bv lO0C md 15-3j°C respectively. The tempennire profdes of rhese tsvo coiidirioiis arc shown in Fiswres 3.5.3 ;uid 3.5.4. .ifter the esodierm, die rempeciture of the re;icti»ri misrure retumed to die initial mould wdl temper-mre ÿfter 10 minutes. The higher ;md lowr tempecinires studied exh promoted incresed diffusioii md lower cataiyst deÿcuntioii respectively. To deremiiic rlie conrciburioii of the nvo eïfects, polynerizatioiis were carried out over tliis wide rmge of mould wdl temperamres.

The effeects of mould wÿll tempemture on die moiiomer coiiversioii levds :ire showii iii

Figure 3-55 and the resulü are tabulated iii .\ppeiidis H. -4s seeii. ;L sigiitiauit effect of tlir mr>uld

\v*d remperdture on die moiiorner conversion ocLun ;it bodi of die temper.iture estremes. -At 114 )O(:. it weas espected that monomer mobility wouid be the 1i;ghest but dso at diis remper;iturc mi uicresed probabiliy of cardysr deactivatioii. The coiiversion at this temperature averased 60.7 1 1.7

*'O ivhicli \V;E much lower thÿri the be~iclunarkaverage. Tliis lower coiiversioii provides evidriicr rli:ir signifiant c~dysrdeactivatioii or irihibitioii of die polymerization mecl~misnioccurred offsertiiig the increÿsed mobility gained at this liidier tempennire. Fmm the 1iter:inire snidies of the eifeçr of' temperature, die optimum temperature for Cpp'ui tduetie solutioii wüs reported at 70OC.1~31 For die

6ii°C ru, in diis study, it w:is fouiid tliat tliere wÿs no improvemriit compared ro die 23O(: miis :uid die cunversion was 75O/a. Tliis result iiidicates that die catdysr iicrivity cm be m:iiri~uiied ;ir diis Figure 3.5.1: Reaction temperature at mould wall Figure 3.5.2: Reaction temperature nt mould wdl temperature of GO0C temperature of liO°C

Figure 3.53: Reaction temperature at mould wall Figure 3.5.4: Reaction temperature at mould wa11 temperature of O°C temperature of -20°C Figure 3.55: Effect of mould wall temperature on the monomer conversion temper~mrebut dso suggests th;ir die conrenioii is iiot difhsioii limited. .At tliis temprr;imrr hjr a polymer conraining 25O:o monomer, the Tg of the system estirnated using the t'rerzitig poiiit ot rlic sryreiie monorner uid die Tg of ancric polystyreiie would be 57OC Holding die mould \vdl

tempemure above the rystem Tg should have resulted in ai incre-asr iii die "10 coiiresion. From rlw plot it is s1iowi.n dut the higliesr conversion values at 83% were ;icliieved at the lower moidd temperatures of o°C, -WC md -3U°Ci This resdt is sigiificaidy hidier tllm tlie beiiclimirk average and hin that the cadyst activity is actually higtier at lower tempemmres. Giveii dic inabiliry to conrrol the esodierm, it is difficult to disbnguish wlirdier or iiot dle polymerizitioii .ir lower mould temperatures is causing the higiier acririry or just impro\.ed hear tcuisfer. From the rime sudu it \vas found tliat the m~jocityof the reïcrion occun withai rhe tirsr 2 miii. Fn~mrlic temperanice profiie, ir cati be seeii diat the average re~ctionremper.iture diiriiig tliis period wis iior :ir tlie set mould \dl tempennire. llius, it is believed the lower re;icthi temperxure improred rlic canlysr activity due to improved heat tmisfer. .At rhese tempemures, a diffiisioii limitation sliould li;ire ocsiirred but it seems diat the eiih;uiced c;ir.ilyst :ictivin orcrc:unr die reduced mobili- tiiiril miodier çonrenion phrem wÿs reached. .b. seeii from die plot 35.5, rlir crmves shnpr of rlir unve is sdarro the fmding of ZambeUi.Jl However, the highest acùvity i>ccurred ~t the lower mould waif rempentures ,and not ar 70°C, the reported optimum ternpenture of a Cp' soiutioii polymerization. The results presented here are sirnilac to fidings of Baird et id.- However, if rlir average reaction temperatures are considered over the fint 2 minutes ÿs compured md showii iii nble 3.4, the results ;ire comparable to Zmbelli's. As seen, the mould wdl ternpeninires :ire consistend- lower thÿn the time weiglited reactioii rempentures; ;ir die O°C mould wdl tempermirc the reÿction temperature approaches the optimum temperiture for die çdystacrivic.

hlould \W Tempenture 1 .\venge Reactioti Tempefiinire

-30 OC 6t.I OC: --

(1 T 71 OC: Room Ternoer~ture 93 OC: -1 Go OC 110 OC:

110 OC: 126 OC: Table 3.4: Mould Wall Average Reaction Temperatures

3.5.2 Effect of Mould WaU Temperature on Maceria1 Properties

Siiice it wÿs foutid diat the mould waii rempenture sigiificliiidy iiffected the cr~n\.ersioii.rlic evaluarion of the polymer properties involves a disnissioii regirdiiy the cïrdysr xtivity ;ir rlic differenr rempentures. The effect of mould ml1 tempennire on the pdymer compositioii \vas determiiied by die extraction of the fractions in .LEK solvenr. The :iverage sPS fr~ctionspruduced at die diflerent mould wall rempentures are shown in Figure 3.56. -4s sliowri, die effecr of modd wall temperature on die sPS fiaction wÿs ais0 prominerit. .At 1 lli°C, die syidintxtic kictiori

dropped ro a low of 47 O.0 demonstratiiig, at diese Iiiglier temperamres, il loss in the syidiot:lcric catalytic actirity wliicli uiould dso esphin die corresponditig drop in crmversioii. Tliis is çorisisrciit widi die riiidui,p iii the lirerature, indimtiiig diar ar Iiigher remperuures. syidiotactic cacilytic sires cui chmg ro aspecific sires produciiig :inctic polymer.3= ;\t 6O0C, die syiidiocicric ti;ico«ii was ;ilse stable at this remperdnire ÿnd no indic~tionof ÿty reduction tn acti~iyWIS gk~ri by the conversion. The possible esplmation for both of die c~cd-sractivity reductioti ar Iiigh rempentures ma)- be due tu die iiidier pdtemperatures ÿbore 130°C. (ln the odier hïiid. it ws obsemed that similar perd temperatures of 130°C were dso acliieved in the misirig sud- :uid chose results show that the sPS fr~ctionremairied unaffected still at 63%. (Plrase rekr to Apperidis

H). Thus the loss of syndioracticiq is arrributed ro the iack of heÿt tcmstër ïiid the prolungd IiiigJier rcxtion temperature. For the O°C mould temperature, no change \vas observcd in die syidi»cictic fraction. Huwever at -30 md -?b°C, die s~ndioracticfnctioii dropped to benveeii 47-55U1~, indicatiig a change ui the cariytic mechmism. Since rhrse mouid remperatures wwre lower tli;ui dit. benchmark condition, less catdyst deactivation sliouid have occurred ÿiid diere should be no drop in the hrmxioii of die syndioncric portion. This loss of syridionctici~lielow O°C is co~isistc~itwirli

Baird et xi. imdings tliat at rtiese tempentures a arbncationic mecli;uiism predomin;lres fiirmiriç mctic polystyeiie.= Even rl~ougiidie conversioii ievel is sirnikir n) die r PC m11, ir is prissil)le rli:ir rlic iddirionai conversion xhieved ïfter the tempemmre dropped below OuC furmed ardctiç polyrner.

This would suggest that the polymecizauon rates at these sub-zero temperatures were acndy sluwer in order ro conven a portion of the monomer to sPS and a greater fraction ro aPS. This forrnauoii of such i high hction of sPS polymer below O°C is unrepocred in tlie literiture. The conves sliape of the plot of sPS hctions is similar to Chien's fmding but once again the shift in rhr oprimum remperarure uidicates that heat transfer üi the RI&[ bulk polymeriz~rioiiwiis probably iiudequarr to c;un out most of the reactioii at the lower remperatures.3'

In most conveiioond polperintions, the reÿctioii temperature usudly has a geat effecr mi the rnolecular weight of the polyrner ch-~isfomed. GPC resuits of tlie s:uriples produced at r:uyiiig morild wd rempentures are ploned in Figure 3.5.7. .\t 110°C, rhr GPC results sliow dxir lowcr molecular welgh t polymer was fomed. 1Iolecular weights ÿroutid 77JJOO g/rnol were pn~duced which me siguticaiidy lower thaii the L26flOO g/mol beiichmark m«lecul;ir weigiin. Ir ws idso obsemed t1i:it the molerular weigiir chstribution was slightly iiÿrrower ;it a dueof 2.8. Tliest. rfiults are not utiespected silice it is well hiown tiiar, P-tiydrogeii elirninluoii ç;ui play :L iiLmitlc71ifiçïlirrole in

Figure 3.5.7: Effect of mould wall temperature on the sPS W. mg. molecular weight limiting die molecdar weigiit teiiding to narrow the moleculÿr weiglit disrributioii :it hi&

temperamres. This lowering of the molecular weight at this tempermtre is consistent with the

fuidings for other metailocene cadysr systerns.JRJl-'-' -At 60°C it ws fouiid rhat no signiticair

difference in die molecular weight occurred .and rhis result is dso corisisceiir in tiiat no 1-use drop ei

molecular weights shouid be observed und the reported optimum tempemture for die Cp' card~stof

7U0C is surpassed. -At lower temperatures, P-hydrogen re~ctiorisoçcur less frequeiidy *and Iiigfier molecular weight polymer is usudly fotmed. -At rernperarures be1ow rotim temperature, much higlier molecular weiglit sPS wu produced, averagïng 300,l)i)O g/mol. This iticrease in rlie molecular \i;ci$ir confirms diat les p-elimiriatioii is &ig place. Sirrulrir GPC rin;dysis of tlie d"S fiactions iridic;ited dur iow molecular weight aPS sdl beuig formed ui the liJ,OUO-30,(JO(J g/md cuige. nie m«kcul:ir weighc distributions dso remained unchmged escept far a slight iiicreüse in tiie polydispersiv ;it

110°C, probably owiiig to the gretter tnctiori of aPS. Iii g-iie~il,rlie moledar weiglits producd from die RIXI bulk polymerization are much lower those reporred in the liter;iture.-jl .-Udiougli direct cornparison c;uinot be made siiice the li terature vdues were reported ;it differeiir c;it;dys t concentratioris, die lower molecular weiglits my be represeiitative ot' 3 rextioii carried riut iir ;i higiier average rempermxe typiced of tiie bulk pol ymerizition condition.

Given die observed changes in die cataiytic activity, \dues of the stereore&irity ;uid rnelting points of die smples were dctemiiied. 13C NilR of the samples iiidic;ited th;ir die t;icticiry remairied at +99% purïty at dl die mould temperatures. This w;& vetificd bu the DSC vidysis of tlie

smples wiiich showed tliat the rneiting poitirs rernained in the 265267 OC: mige. From rhe Ixk of chiuige in the stereore@u-ity,ir seems that the syndiotactic po1ymeriz;itioti mecliariism is uti;ifft'crt.d bu tempenture, demonstrating die rc~busniess of the CpTihIe3 caraiyst. The stability of tlic mechviism is attributed to tlie Cp' lipid, whicli is stabilized bu tlie 5 metliyl goups. This tiiidiiig is iricorisisteiit wirh the results obsen-ed hi Chieri's CpTi(C)CJWri)3/htio s~stern.3~Cp' systcms h;ir.c been shown to be stable at hidi rempentures but iio results have t.iecri reported fiir pci1ymeriz;irroiis

;it juch Iiigli tempeciturcs or in bulk coiiditioiis. 3.6 Conversion Limitations of the Polymerizaa'on

In diis snidy -and previous smdies, the masimum cotivenioti achieved from comp-adle polymerizations mged from 8U-85%. blmy different approaches ÿnd techniques have beçii employed ui an arternpr to overcome this conversion limitation. niese approaches have mostly aimed to reduce the diftiisioii aid heat trmsfer iimirdtbns. The conveiitiond approtich of incresliig the reiicrion temperature to maiiitxin die fluidity of the systern wbiie qiiig to ii~oidcaedysr dextivation tailed to increase the conversion. Cernidy, at temperatures higher thari the TL:of the sysrem, no difhsioti Iirnintion from the $ssy phase sliould occur. .Ar tliis tempemture, questioiis of caralyst actili~:ue still n concem but from the reacrion the snidy ir WLS demoiisrcired rhat evcii after passing rlirough die 17U°C peak temperature, the polymerizatioii çoiitiiiued hr srverai lieurs resulting in ai incrase in the cornrersion to mother limitiiig due. Howerer, iti tlic rnould NXII tempermm snidy, mit;iiniiig die Iiigh mould temperature does residt iii a reductioii iii çatdysr

:ictiviy. .-\trempa to polymerize at 2 modente temperature of GO0C resulted iii no coiiversioii improverneiit. .At this temperature rlie c:itdyst actirity should Iiave rem;iiiied iiiracr w-hile e1irniii;iriiig the diffusion limitation. Iroiiicÿlly, the Iiighest coiiversioiis were acliieved ar Iuwer temprratucs. Ar these low temperanices, the mobility of die system sliould Lx quite hitidered being well brlo\v rlic system Tg. Possibly ;ui estension of the cadysr life or an iiicrease iii rlie catalyst ;lctivity m;iy hvc occurred resultlig Li lugher coiiversioiis but the dass effect myIi;ive coiistrxiiied die coiivrrsioii.

From the previous work of Bÿlier et al., other studies, iiicludiiig iiiçreïsiiig the oir.ilysr coiicriircirioii by 1iJ fold, resul ted oidy in a slight uicrease in cotiversion.~~Iiicrelsiiig die cmilyst c»iiceiitr.iri( ~ii sliould have circumvented the diffusion limitation by proridiiig a surplus of cÿtalytic sites. ;Uriv~u$ man- other polymeriziitiori trials have beeii anempted, such as the use of differeiit heit tnuisfer mediums ;uid mould shapes to controi the tempenture rise, noiie of diem sliowed irnproremeiirs iii the ~onrersion:~Based on dI the currerit ;uid prerious firidiiigs, it is believed t1i:ir die re;icrtoii cotiversioii is rieirher completely diftiisioii limited iior temper,inire limircd. Tliis lads to ;in aiternative rsplanation that m;lv be related ro ttie unique nature of the SI'S polymer. It w;is noticed that the samples were drïed, and oidy after 1 month did rhey reacli çonstuir weight. This seems to be escessively long. Removal of solvena €rom ;unorplious polyerj should not dethis loiig. -4s mentioned in the titemture, crystalluie sPS is polyrnorphic. Mmy cq-srdliiic tom cm esist depending on the conditions under which cystallizatiori is mried out. It k possible. due ro the cr).stdlüie nature of sPS, that the monomer is beuig trapped. Referring ro the Iielicd 6- form, there is evidence that this fom is produced bu solvent induced cqsnlluatiori (SISC) ;uid di;^ sr~blesolveiit rnolecular compounds ;ire fonned. This wy: shown by Cliarmi" md Guenrti2 h)r toluene ÿnd bemene with sPS =id it is hi@y probable diat styreiir moiiomer cm fom a simi1:ir comples. Ir liiis ;ilways been observed diat die rextioti misnire soliditin or sels wirhiii 15-30 seconds. From the polymerizatiori trials widi bulk styrene and 3/50 styreiie/tolueiie it h;is bccri observed that when shaking die reactiori misture, die viscosity iricrecise is ncx gxiu.d ;uid occurs \-en suddenly. This solidification m;iy be due to the presence of high mole cul;^ weight pc~lymerbut ir midit dso be due to the crysnllization of the sPS polyrner. If the prcserice of die mo~iomer\vert: ro id iii SIS(:, it is possible dm tliis gelling is due to die rapid crysr;dlizatioii of SI'S. This cipid crysralliz;iUon may be forrning a styrerie-sPS cornpies, which ma! be biiiding die moriomer possit~ly ui die helicd con fomdtion, preven ring incomplete convers ion. Previous triais using 3 (4) merh!-l sryreiie as ttie moriomer uidicated dut up to 93% coriversioii c;ui 11e actiieved but resulted in rhe complete Ioss of cry~t;illinity.~=Uthougli iuiother conversion p1;ire;iu wis fourid, ;i difhsioii;d limiratio~imiiv have occurred due to the glass effect gwen the conditions it w;~pdymerized undcr.

To rest this hypothesis of monorner eritrapmerit by helicd structures, FRR ;iridys~swis cxried out on the undried polymer smples to determine whicli c9st;d structure tiad beeii hrrnd during polymerizatiori. The FllR spectmm in die regions of iriteresr hr ;ui utldried smple xi. shown in Fipires 3.6.1.3.6.3,3.6.3, 3.6.4 aiid 3.6.5. For comparisoii of the FTIR assigimetits hr rlii. Wacmiuiuber (cm-')

Figure 3.6.1: FTIR - Identification of the sPS helical foms in the 400450 cm-1 region

Figure 3.6.2: FTIR - Identification of the sPS helical foms in the 860-940 cm-1 region Figure 3.63: FTIR - Suggested presence of zigzag forms in the ii00-1400 cm-i region

Figure 3.6.4: ITIR - Distinguishing the S fom from the y form in the 940-1020 cm-' region

Figure 3.6.5: FTIR - Identification of the amorphous form in the 820-860 cm-' region sPS çrysd forrns rehr to Figure 7.6. -L; shown in Figure 3.6-1 in rlir 4JOUjo cm-' regiori. characteristic peaks of the helicai corifomiations of sPS are detected Ir 5110 uid 570 cm-;. In die 80i 1-

940 cm-' regon shown in Figure 3.6.2, a Iiump/shoulder ar 937 cm-' is dso present reinforcmg die presence of n helical structure. In the 1100-1400 cm-1 ange sliown in Figure 3.6.3, i~sdl peuk :ir

1222 cm-' indicates the presence of some pl3nu zigzag confomtiori corresponding ro die a or P cq-srahne focm, although die senes of sdpeaks benveen 132U-1375 cm Iiaw more resernb1:uicc to tlie helical conformations of 6 or 7 cqsnlline form diai tlie pluiuiÿr ziLq;1gstructures. Frorn tliesc prk, the defuiire presence of :L helical tom nid possibly some ziLgzag tom 1s iiidicared. Furrlier inspection of the 966 iuid 977 cm-' p~~ in Figure 3.6.4 show a Iack of uiteiisity differerice Iwnvwi the nvo, wliich ri-urows the identification of tiie helicd structure to the 8-form. The liceciturc spectm depictirig the intensity difference benveen die S ÿnd y ioms L: sliowri ui Fihwre 2.8. For hrther idemification of the specific zigzig structure, a cornpÿrisc~riof die 831-860 cm euigc

Fi-gure 3-65 wirli Fihqre 2.7 resuits Li a closer match widi the ;morplio~isform. Tlie ;ibseiicc of ;i shoulder or peak ar 855 cm-' le.aves the zigzag form identification üicoriclusi\.e.

Similar ardyses were carried out ori the 110, 0 ruid -76 OC ~;unpIesand were hurid to eshibit simrlar specrci. The orily differeiice vas witli the -26OC smple, wliicli Iiad ;ui abserice of rtic

1313 cm-1 peak iridicatiiig no zigzag structure was hmed. It sho~ddbe tioted diar tliese samples contained a significiirit fraction of ;imorplious aPS that m+- be miiskirig some of the obsen-ed uitensities. Reg~rdess,diere is evidence to support tliat die Lforrn was formed, suhqestirig th

STNC may tAe place during the polymerization. This 6-fonn kas oril! beeri reported diiririg clic formation ofsPS gels and is uiireported hrbulk polyrnerizcd materid. Gireii rliat tliis 6 c-sr;d i<)nii is present, the iiest questian would be whecher or tiot there w.s; sufficietir cr).st;lllirii~to tcip the residud moriomer. Crysral1uiit-y estimations from DSC ;uialysis based ori tiie entl~ilpyof smiplc rnclting comp;ired to t1i;it of :i 1( 10 9'0 crystdliiie sPS ;ire showii in Table 3.5 whle the cornpletc Es tirnated Crvstallinitv

BM #4 oc 8 1 "/O 110 OC#3 66 9/0 Table 3.5: DSC Crystallinity Estimates of sPS Samples

çdculatiori is showii in -4ppendis 1. It has been reported that DSC crystallinity estirnates tend ro tx

high since cold crysdlization cm occur. For the DSC runs used to estlmate the crysrdliniry, :i styreiie

evapontioii peak was obsenred but no cold cqsrdizatiori pe;k .ildiciugh, die styrene evaporxioii

mybe mhngthe cold c~srdlizauon,die resuls do suggest rhat die sPS portion in the srniples 1s

higtily çq-sdline. .-\ quick calculatioti based 011 the polymer yield, die conversion, sPS friction ;uid

the estirnated cryscrlliniy aui indicite the ;imouiit of çrystalline sPS polymer. If ai eyui\:Jriit

amount of monomer is tnpped by die sPS crpdline polymer in ü 1:1 moiiomer to sPS repeatiiig

unit mtio xi shown for toluene aiid benzene complexes, c:ddatiolis show tliar tliis entr.ipmetit is

tiighlv probable. miese predictions ;rre shown in Table 3.6.

Description Polymer Conversion aPS/sPS sPS s PS (7.s r:illine Prctlicted Predis tc~l vieid ('"4 pol!mer Fraction Polymer s PS polymer Ctmvcn[t IH (@ (€9 p.$1 (@ @j vield (,@ (Cl,, BAI #3 3-18 78.3 1.70 59.5 1.01 t 1.69 3.39 7 1 ------+ - -- - BAI W 2.11 75.5 1-57 67.3 1.O7 -- -- 0.74 - 3.33- -- (18 -7 369 83.7 325 47.3 1.06 0.86 3.11 1 - ---26 OC ----- 110 OC: #2 2.33 72.7 1-67 47.4 0.79 0.52 2.19 7~ Table 3.6: Predicted Conversions due to Monomer Entrapment by sPS Crystals

For esample, gwen 2.7 g of rhe undried R.hL #3 polymer sample wirli 78';" conversion, aïter dryin%

ordy 1.70 g of aPS/sPS polyner remains.

aPS/sPS polymer = 2.2 g x 0.78 (Oh) = 1.70 g (Dried Polymer)

.\fter estrxtiori in ,CEK solvent, it w~ tourid tiiat the sPS fc~ctioriw;rs oiily GO0~'o.

sPS polymer = 1.70 g x 0.60 (Oh) = 1.02 g

Therefore, ody die 1 g ofsPS polyner wm able ro ccystailize to W'o ;is detenniiied by DSC. If the rnonomer/polymer repeÿt unit entmpment ratio is 1:1, rlieii «iiIy 0.60 g of rnriiiorner csi bc locked within die crysnlline chahs. Back caldating the addition of dits 0.69 g of tr~pprdmoiiomrr and the orignal amount of dded pol ymcr, n predicted polymer yield resula.

Predicted Yield = 0.69 g + 1.70 g = 239 g

.-Uthougli diis is a rough esthte, the cdculated polymer yield cniisists of die îPS/sPS polyrnrr fomied and an equivdent mount of monorner trapped by the cqsrdluie sPS-

Calcuhted conversion = 0.69 g/2.39 g x 100 Oh = 71°h

The c;ddated coriversiori vdues are ÿmund 70% but if the crystdlùiity estimates ;ire irideed htgli. rlic cesults would be doser to the esperimeiid conversions. .Utliough diis styreiie monomer eiirmpmeiir is ï hypothetical esplanÿtioii, the resuln do explairi why a convenioii Iunitarioii esisa.

After dl of rhe iiivestig~tiorisinto improving the moiiomrr coiiversioii of die RI.\[ SI'S ceaction, a rasonable esplÿnxioii to the coiiversion limitatioii h;is ber11 huiid. -YI the atrernpts of adjusrui~die reïctioii conditions to improve the rnoiiomer mobility or rn;iirieiriiig the cacdysr

;ictivity cilrd ro uicrease die conversion sigiiificmdy. This sugests thar rlie polymerizitiori IS neirher difhsion limited nor temperature limired. Iiistead, it is belirved rhar SIS(: is occurriii~by rr~ppuigrlie monomer within sPS's helicd cliaiiis. It is this entnpmrnr of rnoiiomer rliiit is c~usiiig the polymeriz~tionto cme preminirely before cnmplete coriversiori cm be reaclied. Furtlier snidics into controlluig die type of sPS cq-snlliiie fom produced during die po1yrneriz;~rionsrem w~ircmred. Chapter 4 & 5

Conclusions and Recomrnendations 4.0 Conclusions

In this study of the sPS RIM polymetiz;ition, che effects of die esreiit of misuig, reacrioii

Ume .and mould 4 rempenrure on the monomer convesion aid mted properties wre

mves tigated.

For the benchmark polpecizations at room tempenmre aid with a reaction tirne of oiie hour it \vas found that die average conversion was 76%. nie rcsulùiig sPS fraction \vas 63% mid exhibited a moledx weight of 126,000 g/rnol with 2 polydispersity of 3.7. The ;iPS furmeci u;is luw moiecdar weigfit between 1U,i)U(J-3U,1)00 g/mol. The sPS polymer wiis steriçdly puft. ;la deterrnined by NXIR, wliich was dso contirmed by die corresporidixig meltitig poiiit of 267OC.

Ir was fouiid dut vqiiig the mould wall tempenture Iind die most promuieiit rffeçt oii tlic

RI.\[ polynerizition. Controlling the modd wd rernpemtuce had the overdl efkt of moder.itiiig die average reactiori temperature. Iiicreasirig the mould wÿll rempemture to I loO(:decreiüed tlic conversion ro 70?0 and lowered die sPS fcictioii to 470/0. Decreasiiig the mould \dl tempeciturr below room remperxure increiued die coiivesioii to 81% but rempecinires belmv 0°(: ciecre;i';ed rlic sPS fr~ctioiito 47Oh. It wiis dso fouiid diat die moleculx weidit of die sPS polymrr ctiultl Iie iricreased to 20(),Ui )(.) g/mol the inould tempeciture was lowered, iiidicitiiig tliat Iess P-liydrogm elirmnarioii occurj. Tlie stereoregul:irity ;uid me1 ting point of the sPS wece uiiaffected bu the mould w-d temperature sliowiiig the syndiouctic insertion mectimism for die Cp'Ti\[e, systern \v:is uiiaffected.

It wifi Found that longer polymerization times mi iiicrease the moriomer coiiversioii up ici t31"/0 but it wu discnvered tliat the majoriry of die po1ymeriz;itiori is romplete (76%) ;ifter 2 m~iiures-

However widi re;iction times garer di-m 6 lm, it was fouiid tliat ilii iiicre;ise in tlic sPS mcilec~il:ir weight to 3U0,OW g/mol occurred. The sPS fmctioii was uriaffected Liy the re;ictioti time itidic;itiiig the catdyst mechviism rmiiiniris the bdrince of syndinnctic ;uid ;icictic polymer. llicse rcsdrs slio\v diat the cataiyst system cemains active ÿfter passing through a pe.A tempeclnire of + 130°(: 31d

conwiued polymerization cm occur.

The estent of rnising of the RihI polymerization showed litde effect un the conversion iuid

sPS fr~ctionindicatkg that the process is not rnixuig Iimited. Hoivever, a sliglit uicresr in rlir

crmvrrsion to 789!0 wÿr observed with a I.xger diÿmeter mishead, suggesring die :unouiit of interfKi:il

ue~/cotitactmay be of importance.

Giveii rhe inability to increase the conversion significmtly uiider the variety of coiidiriciiis

anempted, it is believed diat the sPS polymerizaaon is neither diffusion lirnired nor remprrJnire

limited. In~esti~qtionsof the cq-stailine nature of the sPS polymer produceci ceraird that rlir SI'S polyner assumes ï tielical confomÿtioii, nÿmely die Gform, diat cm oidy be hmed by the proccss of solvent uiduced crystdlization. it is hupodiesized diat during tliis SISC prticess, tlic moiiomrr ls bring rr~ppedwidiiii die crystduie regioiis in 3 sryrene-sPS complcs. DSC ÿiidysis lias iiidicared tlic w-produçed sPS is Iiifly crystdine wliicli suggests tliat this cryscd eiirclprnetit 1s Iiigtily p1:tudilc.

Tli~is~r is believed diat the rianire of die conversion limitanori ui die sPS Rb1prcxxss is liriked ro the eiitnpment of styene monomer widiin the sPS Iielical chains.

In grierd, it was fouiid diar by vqi~igthe misuig medind, reactiuii time iuid moiilci \v:iII temperature, oidy ï rni~urnurnconversion of 81O41 /avs achieved. Ciider bulk conditions, ir \v:ü discovered diat die majori~ of the raction is complered iii 3 miiiutes imd thr rtic

CpTi!IeJB(GFs), catalyst system was faidy robusr in producing sPS poly-mer uiider die varie- of conditions investigted. r\ conversion limitatioii to the sPS polymerizatioii dors esist ;uid ~r ic, believed to be mhereiit to the niiture of the crys~dliiiepolymer. 5.0 Recommendations and Future Work

This study and previous studies have revded that die developmeiit of the sPS RIlI proçrss

is quite complicated and the high conversions required are stdl unattaïn;ible.

In the rnixuig study, it was found chat a larger diamerer rnislir~dpromoted E-ter misuis

which mihave incrased the conversion slightly. During scde-up of this pnicess, diis Eicror

become impohuit ;md hence, a snidy inro die effect of interfacial coiiracr widiui diifereiir midirïd

desigis mi?be IieIptL1.

It wu evidenr in die mould nid rempemture study, rhat coritrdlhg the rractioii tempeciturc

1 challenge. Ir was mentioned chat a higjdy specialized apparatus would be required for rfficictir

heat tram fer. Investigations uito usbis a mould constructed out of metai witli a 1;ug.e sururt:.içr;uei

mq dlow berrer coiitrol over die ceaction temperature. ;Utliougli it is doubttLl diat Ixge iiicre:ism

in the conversion would occur, the polymer properties would benefit.

It is uiihowri whether die coiiversioii limiratioli is catrilytic. It would be iritere~tirigro

invesripte tlie e Eectiveness of die iiewer, more s nl~le,higlier tempenicure ç:it;Jys ts dix liai-e becti

recendy discovered. Higher polymeriz;itioii remperdtures m~yprevriit/del:iy the tiirmari

ityreiie-sPS cornples. .A more stable cardyst will dso preveiir the rn;iterid property deteriomrioii ;ir

higtier reiction temperirures.

Oved, die most esciting coiiclusion w:ls the possible eiitmpmeiit of die s-rene moiiomrr

widiiii die crysrdliiie structure of sPS. Studies iiito the staliility of rliis s~reiic-sPSçomples rii;iy

proride :m undenrmding for its fomi~tioriwhich my, ui tuni provide insislit for its preveiirioii. Tlic

use ofditTerent additives to modi. the crystalliriity miy have a sigiif?c;ult impiict on tlie cririvttrsioii.

Iiivestigations into the use of :i volatile solvent diat is pretërentid tr) ti)miiri~;i more stable comples

dian die styrene-sPS comples ma. have tlie desired effecr of iiicre;c;uig die conversicxi wliilr ilo ou- e-ay remord of the solvent. Ciiforniiiarely, the choice and use of I;u-se quiuitities of iidditi\+çsin A

RI11 process is uridersir;it->Ie;uid lirnited by the orgmomctdlic nmire of tlie c;it;dysr systcm. References

1. .\Iark, H., Biliales, S., Overberger, C., hfenges, G., Encvc1opedi;i of Polyrner Scieiice iuid EnPineerïn~LTÏiey and Sons tnc., Toronto, 16, 1987, p. 1 2 Ishihara, N.;hramoto, M.; Smd. Surc Sci. Catal., 1994, 89,339-3. 3. Ishth-xa, S.;Seimiya, T.; Kuramoto, M.; Uoi, M.;.Ilacromolecules, 1986, 19,34652466. 4 Guem, G.; .\Lusto, P.; bz,F. E.; .LIachight, WJ.; bfaliromol. Chem., 1990, 19 1.21 11-2119. 5 Musto, P.; Tavone, S.; Guerm, G.; De Rosa, C.; J. Polym. Sci., Pm B, Polym. Phys., I1197,3j, 7. lO55- 1U66. 6. Sapolitano, R.; Ptrozzi, B.; Macromolecules, 1993,26,7325-7338. 7. Vittoria, V.; De Caridia, F.: Caroteriuto, hl.; Guadiigno, L.; J. hhcrcmol. Sci. Phvs R lL196.35, 2. 365373. Y. I'ittocia, V.; Russo, R.; Polymer, 1991,32, 18,3371-3375. 1- Deberdt, F.; Bergturims, K.;Polymer, 1993,35, 10,3193-3201. li 1. Roels, T.; Deberdt, F.; Ber@irnaris, H.; .L[acromolecules, 1994, 27,G216-032iL 11. Deberdt, F.; Bergtu-nms, H.; Polymer, 1994,35,8, 1694-17W.

12. Guenet, J.11.; Deluca. MD.; Daniel, C.; Polymer, 1996,37,7, 1373- l28(i. 13. Chat:rili, 1-.;Shimme, Y.; Itugki, T.; Polymer, 1993,34, 8, 1620-11134. 14. lI.mfiedi, C.; Del Sobile, hI..A.; hlensitieri, G.; Guerra, G.; Rap;iccruolo, M.;J. Polym. Sa., Part R, Polym. Phys., 1997,35, 133-140. 15. Sinri, H.; I;;imu~sLy,K.'.; .-\dv. Orcgaiomer. Cllem., 1980, 18, 09. 16. Kmuisky, W.; Mri, AI.; Sinn, H.; VUoldt. R; hLakrornol. Cliern., Rapid. Crimmuii., 1083,-t, 417. 17. Ewen, J .; Sci. .&II., 1997, My, 86-91. 18. Campbell, R.E.; Newman,T.H.; Malang, MT.; .Lfacromol. Symp., 1997,97, 151-160.

1'1. Zmbelli, .A., Pellecchia, (1.; Proro, ri.; 1IacromoI. Surrip., 1795, 89, 373-383. 3?,. Pellecdiia, C.; Longo, P.; Proto, -A.; Z4unbelli,.A.; ,Lhkromol. Ctiern., Rapid Commun., 1002, 13, 365-768. 31. Longo, P.; Proto, -A.; Zambelli, -\.;Macromol. Cliem. Pliqrs., 1995, 196,30153029. 23. Ki;mg,Q.; Quyoum, R.; Gillis, D.; Tudoret, A1.J.; Jeremic, D.; Hutirer, B.; Biurd, >K.; Orguiomet;illics, 1996, lj,693-7(13. 33. Kuclit, H.; Kucht, -1.;Chieri, J.; Rausch, LI.; -\ppl. Organomet. Cliem., 1994, Y, 393-3911. 34. PO', R.; Cardi, S.; Prog. Polvm. Sci., 1996,21,47-88. 25. Chien, J.; Sdajka, 2.; Dong, S.; hhcromolecues, 1992,35,3199-3203.

20. Gcissi, .A.; Pellecchia, (1.; Oliva, L.; lhcromol. (:liem. Phys, 1095, 100, li 103-1 1( it 1.

27. Gclssi, -4.: zarni~ell~,-A.; ( k~u~c)me~dIics,1906, 15, 2, -+si1, 482- 28. \..mg Q.; Baird, .1I.C.; .Llacromolecules, 1995,38,8021-8037. 29. Foster, P.; Chien, J.; Rausch, U.;OrpomerJlics. 1996, 15, 24(KZ4OL). 30. Ishhara, 'I.;Kumoto, hi.; Uoi, !d.; Macromolecules, 1988,21,3336-33Gt). 31. Gmsi, A.; Lmberti, C.; Zmbelli, A.; Llinpzzi, 1.; Xlacrornolecules, 1997, 30, 7, 188C1880. 32. Chien, J.; Salajka, 2.;J. Polym. Sci., Part .\, Polym. Chem., 1991,39, 133-1263. 33. Duncdf; D.; Kiade, H.;Watersori, C.; Derrick, P.; Haddleton, D.; .IlcCdey, -A.; ,L~acromolecules,1996,39,6399-6-103. 34. I lark, Fi.; Bikales, 3.;Overberger, C.; Menges, G .: Encyclopedia of Pol -mer Science ;uid Enpineerin~Jolm Wdey & Sons., 16, 1987, pp 1-36.

33. Russell, K.E.; Tobolsky, A.V.; J. ;\m. Cliem. Soc., 1953,755052-5(154.

36. llark, H.; BiMes, S.;Cherberger, (3.; Menges, G.: Enqclo Envineerinc John mile? & Sons., 7,1987, pp 501-514. 37. Odiai, G.; Pririci~lesof Pol mrrintioii, 3" Ed., Jolin \Wey Kr Som Iiic., Toronto, 199 1, p. 28-5. 38. Rudin. A.; Rie Elemerits of Polvmer Science aici Er rieetirlg, -kdemic Press, Toroiito, 1983. pp. 93(1-73 1. 30. .LImeii, F.L., Hamielec, .\.E.; J. -\ppl. Polym. Sci., 1983, 27,489-505. 40. htacosko, C., F~iiid;unenr,dsnf Reictinn Iniection .LIci\ildiiig, Hanser, Sew York, 1989, (a) pg. 1. @) Pa. 6, (c) pg- 7, (d) pg. 3, (e) pg. 709, (t) pg. 87, @ pg. 93, (11) pp. 93-L10,(3 pp. 193-200, (1) pg. 199 0;) pp. 177 - 182 41. llark, H.; Bikales, S.;(Sverberger, (1.; hienges, G.; Eric Engirieeriw, John Wley & Sons., 14, 1987, pp 73-74. 43. Geer, R.P.; Stoutiand, R.D.; Proc. of the .h~u;il(lotit of the Socle' of Plastic Gigineers, 198-5, 1232-1235. 43. Liu, T'Al.; Baker, W.E.; Scliyn, \-.;Jolies, T.: Baird, MC.; J. 'ippl. Pol-m. Sc;., 1WG, 62. 1 1, 1807-1828. U. Cnpublished work in W.E. Baker's labontory, 1995. 5. .\lena, 11.; Royo, P.; Serrmo, R.; Pellinghelli, M.A.; Tiripiccliio. :\.; (>rguiomer;dlics, 1089, 8, 476482. 16. llassey, -i.G.; Park, A.J.4. Orpiomet. Chem., 19W, 2,245. 47. Harnbv, S.; Edwards, 11.F.; Nienow, .4.W.; ,Ilisiiw in the Prncess Iridustrie5, Rutrenvortli ,uid (30. Ltd., 1985, p. 228. 48- Evans, .-\..\.I.;Keiiar, E.J.C., G~owles,J.; Galiotis, C.; Cxriere, C.J.; .-ùidrews, E.H., Polym. Lis. Sci., 1997,37, 1. 49. Rrmdup,].; Polvmer H;uidt~otk,3d Ed., Joliii \Y'iley & Srms Iiic., 1075, p. 3.Sperluig, L.H.; Inrrodtiction to Phvsical Polvmer Science, 2nd Ed., Jrhi Kïley J: Sons Iiic.. ILIL)?. p. 353. 51. Park, J.Y.; Lee, H.S.; Park, 0.0.;Conf. Proceedùig of the 13" .Guiual hleering of die Polymer Processing Society, 6B, Secaucus, SJ.,June 1997. Appendices and Curriculum Vitae Appendix A - Typical TGA Therrn~~parnof sPS RIM Sample Appendix B - Randornized Experimenml Run List

1 Run # Run Description 1 Peak Temperature (OC) 11 Benchmark (Bhn #1 118 3 - - No Static iCLs.in,q (NSiLI) #1 65 - 3 Luger Dimeter ALsing &DM) #l 126 4- No Static iCLising (NSiLI) #3 131 3 Test Tube Xliuing (rrlcr> 128 6 Benchrnd (BM)#2 126 7 24 hr #1 124 8 10 mui #1 133 9 2 min #1 102

2 min ff3 I

i Additional Replicare Runs frcm I Preno~sSN& Run # Run Description Peak Temperature (OC') --9 9 IO min #2 100 Appendix C - Borane Prepolymerization Study

Run Condition Initial Wt. \Veight of aPS Styrene l[olecuiar Styrene Polymer Ce;) Conversion K'eight @/mol)

Appendix D Cont'd - 1H NMR of aPS Appendix D - Cont'd UCNMR of sPS Appendk D - Cont'd UCNMR of aPS Appendtr E - DSC Thermal Trace of sPS Sample

SCAN PARAMETERS START TEHP. OC 50 RATE K/HIN. 10 END TEMP- OC ZOO TfME ISO, MIN. O PLOT CM 20 RANGE FS mU 20 OFFSET .Y / O 80 PAN TYPE 1/2 LIMIT ' mW SCREEN DYN/ISO 112

FILE NO. EDENT. NO. WE 1 GHT mG

TEHPERa TURE JC HEAT FLOW EXOTHERMAL--> Effect of Mwng on the Conversion Run Description Peak Temp. Rise Polpner kïeld Residud Monorner .Clonorner Conversiori !

eq ce;) e/4 e 4 l+ 'ITM 128 387 35.3 74.7 - -- I

SSM #l 63 7 77 24.1) 76.U I --P ------t SSN #2 131 3.14 26.1) 74.1 1 -- 1I SSM #3 139 338 23.3 -- 76.7 - BM #l 118 754 25.6- 74.4 t - -- t BM #3 136 335 23.6 -- 76.4 -- ?

BM #3 126 718 21 -8 78.2 - + BAL 2.11 24.5 75..5 . 123 --- -- LDM $1 1 2G 1.83 21 -5 78.;- - LDM $2 123 330 20.9 79.1

Effect of Mixine: on the Material Prouercies 1 Run sPS 1 aPS -Adjustcd' Descnp rion Fraction Fraction aPS Fraction ml e.3 TT11 63.6 37.4 937

' :\djiisted aPS fraction c.ucludiiig die miouiit ofs~reiiepolviirerized Li die prrriisiig srrps.

ALixing !dethoJ Residud Monomer s PS :\ci j us rcd + (7.1. ar 95";, Monomer Conversion (?!O) Fraction ;iPS Fr;iction (?q POFI (".'#,) k 1.2 (6) ("/O) t 1.2 (6) + 3.3 (Gj Test Tube 25.3 74.7 636 ---73 7

Large r 31.2 78.8 64.3 31.7 Diame ter LLuing Appendk G - Reaction Time Study

Effect of Reaction Time on the Conversion Reac tion Peak Temp. Pol!mer \r'idd Residual Monorner Tic Rise (3 lionorner Conversion eci PO> ?./O)

.--- .--- 2 min $1 102 349 21.8 78.2 2 128 22.2 10 min #1 133 349 93.6 76.4

Effect of Reaction Time on the ~MnteridProperties Run s PS =\diustedg sPS Molecdar ;PS Description Fraction aPS WC. Mo1ecul:ir Wt- Fciction [x IV g/mo[) Ç s 20' g/mol)

10 min ft3 53.7 32.0 129 3.1 --. I hr #1 65.0 20.3 136 '4.0 39 L3.7 - -- 1 hr #2 62.8 23.8 167 '3.3 16 (3.ilJ I hr #3 59.5 3G.4 104 ,4.2 8.3 k4.31 1 hr #4 67.3 18.1 IiJO -3.4 9.9-~4.15]-- 6 hr 65.0 21-4 185 4.5: 3?-[3--__

Reaction Erne Sumq

A Lising Residud 1 Monomer sPS .idjustecl

Effect of Mould Temperature on the Conversion Run Description 1 Peak TemD.Rise 1 Polymer k'ield 1 Residud Monomer 1 !vfonorner I I cj 0 e,o> 1 Conversion (" :,)

,------23 OC: #2 126 335 13.6 - 76.4 12G 2.18 21.8 78.3 33 O(: #3 --- -- 9- C 33 OC 3-35 13.3 A4 - 133 2.1 1 ----- GO "C 130 2-60 5.0 75.0 A------

110 OC #1 140 205 373 -+ 67.7

1 10 OC- #7 136 333 28.3 71.7

Effect of Mould Temperature on the Material Propenies .\ Iould s PS .id jus ted' sPS a PS ' sPS lklang s PS Temperature Fraction riPS Molecular Wr. Molecuiru K't. Point Tmm~1 ? 4 Faction (XI@Q/~OI) (KIW~~/~O~] r' 11) 1 Vfn) PD11 FDrJ 1 -'6 47.3 39.6 201 [3.91 365 VI + - t--- * -+- -30 OC: 55.5 31.3 186 [34 il [-!-Cl 26 -5 .------. - -. - - - . iJ OC #l 67.3 19.3 171 [3.9] - 10 [4.9] 266 .- 99t . -- il OC #2 60.6 36.3 337 [3.4 .------33 OC##I 65.0 20.2 136 [4.0] 29[3.q ------A--.------.-- - 33 #2 62.8 32.8 167 [3.3] 16 [5.01 367..5 9% -- =c ------. - . -- - - 33 O(: $3 65.0 20.9 10-3 [421 8.3 [4.,51 , - - .- - . ------A---p------. - . 23 OC, +#4 67.3 18.1 l(IO [3.41 9.8 [-!.GI 266 .--- .--- - -* -- 60 OC: 56.3 38.8 143 (3.61 14 [4-6] 267 ------* ---- - 110 "C #I 47.3 36.5 82 [381 363 99 + .--PT - p---4- - . 110 OC #2 47.4 37.3 71 [2.91 24 15.81 ' =\djilsted &'S frxtiori cxcludiiig die miourit oistyrcrie polytiierized in die preiiii.uirig steps.

MouId Temperature Summary Appendix I - Crystaiiinity Estimates ofsPS Samples

S;imple Monomer sPS Description Conversion Friction

DSC Sÿmple Ssample Endothem hfelt Crvsnllizable hIelt S-rdliiiity -\dpistcd~1 LVeigtir Enthdpy Enthdpy Weight Exirhdpy S-~dimn~1

! II 'a hp;) cmn O& (mg) (r /& (O O) Bk[ #3 (Cridried) 14.50 243.31 16.8 6.75------36.1 31.3 673 Blf #3 (Dried) 5.0 109.83 22.0 3.98 36.9 41.3 * 69.1 1 -- - .-. --- BA[ #4 (t ndried) l(J-5(1 187.98 17.9 5.33 33.3 33.7 66.3 - - - -26 OC Wndried) 1O.0O 170.4 17.0 3-95 43.1 32.(1 81.0 j -- - 110 OCKndried) 1(!-25 123 .O6 17.0 3-48 35.3 32.6 66.1 j The "k crystdlinity ha ken adjus ted based on the 'mount of crystdlizablc sPS