Graft Copolymerization of Methyl Acrylamide Onto Jute Fibers Initiated by Peroxydisulfate Catalyzed by Fe(L11)

Polymer Journal, Vol. 21, No. 10, pp 821-828 (1989)

Graft Copolymerization of Methyl Acrylamide onto Jute Fibers Initiated by Peroxydisulfate Catalyzed by Fe(l11)

Rajani K. SAMAL,* Sabyasachi DASH, and Atish K. SWAIN

Makromolecu/ar Research Laboratory, Department of Chemistry, Ravenshaw College, Cuttack-753003. Orissa. India (Received August 31, 1988)

ABSTRACT: Graft copolymerization of methyl acrylamide [MAM] onto jute fiber has been studied in an aqueous medium using potassium persulfate as an initiator, under the catalytic

influence of FeC13 in nitrogen atmosphere. Grafting is influenced by reaction time, temperature, concentration of monomer, initiator, catalyst, and base polymer. For comparative catalytic influence the reaction has also been carried out in presence of various salts and organic solvents. The maximum graft percent of 70.6 is obtained at 50°C for the following concentrations; monomer (0.8 M), K 2 S2O8 (0.03 M), catalyst Fe(III) (1.5 x 10- 3 M) and composition of acetic and formic acid of 2.5% (v/v). From the experimental results a mechanism for graft initiation and termination has been suggested. The extent of absorption of water and water vapors, the tensile properties and thermal behavior of the grafts have also been tested. KEY WORDS Graft Copolymerization / Methyl Acrylamide / Jute Fiber /

Potassium Persulfate / FeCl 3 / Tensile Modulus / Primary Thermogram /

Graft copolymerization of vinyl monomers mm1m1ze the import of synthetic fibers. Al onto cellulose, lignocellulose and their de though jute fiber possesses high dimensional rivatives has been the subject of extensive stability, certain unfavorable textile properties studies since 1946. 1 Graft copolymerization of like high stiffness, very low elasticity, suscepti preformed polymers both natural and syn bility towards sun light, etc. they have tremen thetic provides a potential route for signif dously limited for their use. 2 Therefore, to icantly altering their physical and mechanical minimize the undesirableness for intensified properties. The grafting possesses great poten textile uses, graft copolymerization of some tial for tailoring material properties to specific vinyl monomers onto jute fibers has been end use. Jute, a lignocellulosic polymer, is the attempted during the recent years using chemi most abundant renewable agricultural raw ma cal, photo chemical, and radiation induced terial. It is transformed into multiferious prod methods of initiation. 3 - 14 Among all these ucts due to its wide application for making reports encouraging results have been ob coarse woven fabrics such as gunny sacks and tained by Mehta et al. 4 •5 where the grafted bagging where the cheapness is the essential fibers showed improved tenacity, dyability and factor. Recently efforts are being made in tensile properties while rest of the reports are India and Bangladesh for commercial utili not so much convincing. Further among the zation of jute fibers to meet the total fabric methods of initiation, chemical methods of requirements of the country as well as to initiation of grafting involving oxidizers like

• To whom all correspondence are to be addressed.

821 R. K. SAMAL, S. DASH, and A. K. SWAIN

Ce(IV), V(V), Mn(VII), K 2S2 O8 , KHSO5 etc. nitrogen gas for one hour and were then sealed are promising from the economic and in airtight by rubber capping. The vessels were dustrial point of view and are quite selective in than kept in a continuous shaking thermo nature. Among the chemical initiators per sttated bath, till the mixtures attained ther sulfate ion (S 20~-) has a separate identity of mal equilibrium after which required amount its own. Persulfate ion is known to act as a of the initiator was injected through the rub strong oxidizing agent in an aqueous solution, ber capping. The reaction was carried out for and either alone or in the presence of an the desired time. The homopolymers were ex activator has been used as an initiator of vinyl tracted by repeated boiling of the grafts in dis polymerization. 15 - 22 However the use of per tilled water till washings did not yield any sulfate redox system for initiation of graft precipitate with methanol. copolymerization of vinyl monomers onto cel From the weight of the grafts and parent lulosic substrates was recognised in 1963. Since fiber, the percent grafting was calculated as then persulfate ion alone or with suitable follows: catalyst has been used for initiating graft co X-Y polymerization onto various cellulosic sub Percent grafting=-y- x 100 strates.13·23 -33 The present report describes graft copolymerization of methyl acrylamide where X and Y was weight of the graft co [MAM] onto jute fibers initiated by K2 S2O8 / polymer, and that of the original base poly Fe(III) couple and the effect of percent graft mer, respectively. ing on the properties of the grafts. MECHANISM EXPERIMENTAL The mechanism of graft copolymerization Materials may be pictured as involving generation of Jute fibers (Corchoru capsularis) were pu macro-jute radicals resulting from the attack rified by repeated Soxhelation with a mixture of the primary radicals so.;:-. and er produced of ethanol and benzene (1 : 2 by v/v) followed from the initiator either alone or under the by washing with cold ethanol and air dried. catalytic influence of Feel3 at the jute back Methyl acrylamide (MAM) was purified by bone. Further the macro-jute radical for recrystallization from acetone. A stock so mation may be caused by Ho· radicals pro lution (4 M) of the monomer was used for the duced from the oxidation of H2O by SO4'. 34 grafting reaction. A stock solution of the Attack of the resulting jute radicals on the initiator "K2 S2O8 " (0.1 M) was prepared by monomer molecules at the immediate vicinity dissolving 10.81 g of the salt (E. Merck) in results in graft initiation. Homopolymeriza triple distilled water. The activity of stock tion of methyl acrylamide and oxidation of solution was determined by cerimetry. All jute radicals through primary radical initiation other reagents were used after purification by may also take place as side reactions. standard methods. 1. Primary Radical Production Graft copolymerization was carried out in a reaction vessel carrying out (i) s2O~- kd 2so.;:-· specially designed Thermal let and inlet systems, for deaeration. The de fatted jute fibers (0.2-1.0 g) were immersed in (ii) S2O~ - + FeC1 3 a mixture containing water, required amount so.;:-· +soi- +er+ Fec12 of MAM and ferric chloride. The reaction vessels were deaerated by passing oxygen-free (iii) so.;:-·+ H2O ~SOi- +HO'+ H+

822 Polymer J., Vol. 21, No. 10. 1989 Graft Copolymerization of MAM onto Jute Fibers

Step (ii) of primary radical production seems Table I. Graft percent in K2 S2 O8 initiated graft to be true, as has been verified from the copolymerization of MAM onto jute fiber under the influence of various salts liberation of Cl2 which may result from the coupling of two er radicals er + er~ Cl 2 Salts Grafting% 2. Formation of Macrojute Radical No salt 1.1 J-H+R· ~J" +R-H FeCl3 11. 7 Fe,(SO4 h 7.2

0 (R =SO4 °, HO", and Cl") CuSO4 4.8 NaBr 2.3 Initiation 3. Graft ZnSO4 3.3 K2 SO4 2.2 J"+M~J-M" CdC12 5.8 4.8 4. Non-Graft Initiation CoSO4 Cr,(SO4 h 8.2 MgSO 4.4 R- M" 4 R" + M MnSO4 1.3 5. Propagation NiSO4 4.9 AgNO 1.1 (a) Grafting: 3 FeSO4 10.3 Na S O 0 J-M"+M~J-M; 2 2 3

Jute=0.2g; [MAM]=0.2M; [K2S2O8]=0.0l M; [Salt]= 1.5 X 10-3 Mat 45°C for 6h. J-M~- 1 +M~J-M~ (b) Homopolymerization: and Na S20 enhance the percent grafting. R-M"+M~R-M" 2 3 . 2 The enhancement of percent grafting in the presence of these salts and increasing trend as R-M~- 1 +M~R-M~ cited above may be attributed to the pro 6. Termination of Grafting gressive increase in the rate of decomposition of (i) J - M: + J - M: K2 S2O8 to massive free radicals (SO~-)- They ~cross-linked polymer attack the jute backbone resulting in the for (ii) J - M: + Fe(III) mation of a number of free radical sites, then ~Graft copolymer+Fe(II)+H+ the monomer addition takes place on it. The (iii) J-M~+R· ~J-M"-R complete inhibition of grafting in the presence 7. Oxidation ~f Na2 S2O3 may be due to the deactivation of the initiator through oxidative disproportion r +so;· ~oxidation products ation of the latter.

RESULTS AND DISCUSSION (i) Effect of Monomer Concentration Graft copolymerization of MAM onto jute Methyl acrylamide [MAM] was graft co fibers has been studied with different monomer polymerized onto defatted jute fibers using concentration. The percent grafting increases

K 2S20 8 as an initiator either alone or in the with increase of monomer concentration upto presence of a number of salts as catalyst. The 0.9 M, beyond which it decreases (Figure 1). results of percent grafting for the individual The enhancement of percent grafting in this systems are presented in Table I. case may be interpreted in terms of increase in From the results in Table I, it is observed the concentration of MAM at the reaction site that the presence of all the salts except AgNO3 and complexation of jute with MAM enhanc-

Polymer J .. Vol. 21, No. 10, 1989 823 R. K. SAMAL, S. DASH, and A. K. SWAIN

Temperature/°C [Fecl,]X 104 mol-' 30 O 50 60 70 . 80 90 1 0 110 120 0 20 16 12 8 10

20 5

40 60 10 cf i!: '-.. cf .::: ::: 50 c'.5 cf ft> e 30v '-.. 0 O 20 40 15 0 70

10 80 20 20

10 0 0.2 0.4 0.6 0 1.0 0 20 30 [MAM]/mol ' [K,S,O,]X 1 O' mol-, Figure 1. Effect of monomer concentration ( 0) and Figure 2. Effect of initiator concentration ( 0) and temperature ( e) on the graft percent: Jute= 0.2 g; FeCl3 concentration (e) on the graft percent: [K2S20 8]=0.0l M (0) and 0.03M (e); [FeCl3]= [K2S20 8]=0.0I M (e): Jute=0.2g; [MAM]=0.8 M 1.5 X 10-3 M; [MAM]=0.8 M (e) at 45°C (0) fro 6h. (0) or 0.2M (e); [FeCl3]=1.5X 10-3 M (0) at 45°C for 6h. ing of reactivity owing to the formation of a donor-acceptor complex. Similar explanations sites on the backbone of jute fibers. Graft for enhancement in grafting with increase in initiation by free radical sites both at and monomer concentration have been presented below the surface region of the fibers positively by Gaylord,35 Hebeish et al. 36, and Sama! et contributes to enhancement of the grafting. a/.37 The stagnation of graft percentage beyond

The decrease of percent grafting beyond [K 2 S20 8] of 30 x 10-3 M may be attributed to the monomer concentration of 0.9 may be at (i) homopolymerization by excess of primary tributed to agglomeration of the fibers as well radicals formed from the initiator and (ii) the as poly(methyl acrylamide) PMAM homo other factor due to premature termination of polymers resulting in the formation of lumps the growing grafted chains by excess of pri thereby decreasing the number of free radical mary radicals. surface sites available for monomer addition. Similar explanation for the decrease of per (iii) Effect of Catalyst Concentration cent grafting at high monomer concentration Graft copolymerization has been studied at 38 has been observed by Hon et al. different FeCl3 concentrations. It has been observed that the percent grafting increases on

(ii) Effect of Initiator Concentration increasing the concentration of FeCl3 upto The graft copolymerization was studied at 1.5 x 10-3 Mand then decreases (Figure 2). The various initiator concentrations (5 x 10-3_ enhancement of percent grafting may be at 3 35 x 10- M) at fixed concentration of MAM tributed to forced decomposition of K 2S20 8 (0.8 M). [FeC1 3 ) (1.5 x 10-3 M) at 45°C for a in a transition state on interaction with ex reaction time of 6 h. The percent grafting cess of Fe(III) leading to the production of increased with increase in the initiator con primary radicals on the fiber surface which im centration upto 3 x 10-2 Mand reached a con mediately attacks it's backbone resulting in stant value (Figure 2). The increase may be the creation of a large number of free radicals. attributed to increase in the number of active The decrease in percent grafting at higher

824 Polymer J., Vol. 21, No. IO, 1989 Graft Copolymerization of MAM onto Jute Fibers concentration of FeCl3 may be attributed to Table II. Variation of percent grafting at fixed time the detrimental factor of excess of Fe(lll) ions effect of various solvent composition leading to retardation of rate through prema Graft percent ture termination of the growing grafted chains. [Solvent] ______That has been reported by Rogovin et af. 39 Acetic Formic v/v Pyridine Acetone Methanol acid acid and Mishra et al.40

2.5% 36.7 57.0 60.7 70.7 70.1 (iv) Effect of Temperature 5.0% 32.2 56.6 60.4 68.2 68.0 The effect of temperature on percent graft 7.5% 26.4 56.0 57.6 68.1 60.6 ing is shown in Figure 1. It has been observed 10.0% 26.2 54.6 56.5 62.5 48.1 23.3 54.0 54.6 55.0 47.6 that the percent grafting increases upto 50°C 12.5% 15.0% 14.8 49.5 44.5 49.5 51.4 and then decreases. The increase can be ex plained by (i) increase in the production rate of Jute=0.2g; [MAM]=0.8 M; [K2 S20 8]=0.03 M; active free radicals which increase the number [Fe(Ill)]= 1.5 x 10-3 Mat 50°C for 6h; standard=66.6%. of grafting sites at a greater rate thereby the rate of graft initiation increases and (ii) in 2.5% onwards. The enhancement of graft per crease in the rate of diffusion of MAM into the centage with formic acid and acetic acid at the fiber matrix where grafting is also initiated. cited compositions may be due to (i) acetic

Samal and co-workers41 - 43 have identical ob acid radical (CH 2-COOH) contributing to servations in the grafting of acrylamide onto wards generation of greater number of graft Nylon-6, silk fiber and cellulose, respectively. ing sites on the jute backbone and (ii) swelling The decrease in the percent grafting beyond of the fibers in the presence of formic acid may 50°C may be ascribed to (i) activation of jute permit the monomer and the initiator to dif backbone and the initiator leading to overall fuse into the fiber matrix. Then, grafting is oxidation of the former, (ii) increase in the rate initiated both at and below the fiber surface. In of production of homopolymers, (iii) prema addition the swelling of the fibers also permits ture termination of growing grafted chains by high accessability of the surface of the jute Fe(lll) and (iv) ion premature termination of fibers towards attack by primary radicals, growing polymer chains by transition metal creating more number of free radical sites ions in their higher valence state which has leading to graft initiation. The retardation of been observed by Bamford et al. 44 and Sama! the rate at higher percentage of acetic acid and et al. 45 formic acid ( > 5%) and with rest of the sol vents may be due to (i) the chain transfer (v) Effect of Organic Solvents ability of these solvents leading to premature The effect of organic solvents on the graft termination of the growing grafted chains, (ii) percent has been studied. The results are pre massive formation of homopolymers by excess sented in Table II. of the solvent radicals upsets grafting, (iii) The presence of acetic acid and formic acid shielding of the jute radicals by solvent cage of 2.5% to 5% (v/v) in the reaction mixture arising from interchain hydrogen bonding of enhances grafting, and beyond 5% there is the solvent molecules as a result of which progressive decrease in the graft percentage. monomer addition onto the grafting sites is However at 5% of the solvents the percent restricted. This is in alliance with the view of grafting is less than that at 2.5%. Further it is Kern and coworker46 and Palit and co also noticed that with rest of the solvents a workers.47 progressive decrease in the percent grafting from the control value is noticed right from

Polymer J .• Vol. 21, No. 10, 1989 825 R. K. SAMAL, S. DASH, and A. K. SWAIN

Table III. Effects of graft percent on tensile properties of PMAM grafted jute fibers 100

Elongation 10 Graft- at break Tenacity Tensile Samples ing B.L. modulus % g/denier at break 60 Ol % ::, -" .11' Q) Jute 0 0.9 1.0 110.9 3_40 Jute-g-PMAM 14.8 1.3 1.5 117.2 Jute-g-PMAM 44.4 1.3 1.9 146.1 Jute-g-PMAM 60.4 1.4 2.2 155.7 20 3 Jute-g-PMAM 70.6 1.5 2.4 161.3

200 400 600 900 DOO Properties of the Graft Copolymers Temperature/°C Methyl acrylamide grafted jute fibers have Figure 3. Primary thermograms of parent jute and the following properties. jute grafted with methyl acrylamide: Sample No. I, 0.0 (a) the absorption of water and water vapors (parent jute); No. 2, 44.4 graft %; No. 3, 60.4 graft %; No. 4, 70.6 graft %- increases. (b) the lustre of the fiber increases. (c) resistance towards the attack of mineral uted to the internal cross-linking of the fiber acid and alkali increases. backbone through bimolecular termination of (i) Tensile Properties. The tensile prop growing grafted chains and this imparts elastic erties of the parent and grafted jute fibers nature to the fibers which increases with were evaluated with tenacity (g/denier) and increase of graft percent. elongation at break, following the methods of (a) Thermogravimetric Analysis ( TGA). Huque et al. 4 and Sama! et al. 37 After con The TOA curves (Primary thermograms) for ditioning the samples, they were combed and the parent jute and PMAM-grafted jute, with fiber aggregates of uniform length. The te different percent grafting (44.4----70.6%) are nacity of the weighed samples was determin shown in Figure 3. The parent jute undergoes ed using Zwelgies strength tester. The tensile nearly 45% weight loss between 200-500°C. modulus at break was determined from the This may be due to the amorphous region in relationship: the fibers and partly due to the presence of lignin component. On the other hand, jute Tensile modulus at break grafted with MAM shows peculiar behavior. Tenacity at break The grafts undergo progressive weight loss Elongation at break upto 650°C, with major weight loss of 58%, 83%, and 85% for the sample of percent The tensile modulus at break can also be grafting of 44.4, 60.4, and 70.6, respectively. determined from the slope of the stress-strain Further beyond 200°C the grafts undergo ear curve. In both methods, the same value lier decomposition, than the ungrafted fibers. of tensile modulus is obtained as seen in Table III. Grafting of MAM onto jute fibers This may be due to earlier decomposition of increases its elongation at break, tenacity and PMAM grafted chains on the backbone of the the tensile modulus which increases with in jute fibers. Continuous depletion of the pri crease of graft percent. The enhancement in mary thermograms of the grafts upto 650°C tensile properties of the grafts may be attrib- indicates that grafting takes place more into the amorphous region of the fiber. This seems

826 Polymer J., Vol. 21, No. IO, 1989 Graft Copolymerization of MAM onto Jute Fibers

Table IV. n and £ Values of parent jute and jute-g increase of graft percent upto 60.4. The de PMAM graft copolymers of various graft percent crease in activation energy for the sample with

E higher percent grafting (70.6) may be attribut Grafting Samples n ed to the involvement of more number of % kcalmol- 1 grafted chains in the pyrolysis, as a result of which the graft copolymer (70.6% grafting) Parent jute 0.0 17.6 1.5 Jute-g-PMAM 44.4 24.5 1.0 somewhat behaves as a composite of jute with Jute-g-PMAM 60.4 36.6 1.2 poly(methyl methacrylate). Jute-g-PMAM 70.6 27.8 1.0 Acknowledgements. The authors are highly thankful to Prof. Y. Ikada, Research Centre to be true, as the fiber grafted with PMAM for Medical Polymers and Biomaterials, upto 44.4 % had primary thermograms pattern Kyoto University, Japan, for his continuous similar to the virgin jute fibers even though the inspiration and valuable suggestions. The fi former suffers weight loss upto 58% between nancial support U.G.C., India, New Delhi is 200-650°C. From the primary thermogram greately acknowledged. in Figure 3 the values of W, 1/T and dw/dt were calculated. Further plots of dw/dt vs. 1/T REFERENCES and W vs. 1/T yielded a pair of curves for each primary thermogram. From these curves the I. S. N. Ushakov, Fiz-Mat. Nauk, 1, 33 (1946). values of A log (dw/dt) and A log Wat equally 2. Arthur D. Little, "The Engineering Properties of spaced interval of 1/T were calculated. From Fibers," Incorporated Cambridge, Massachusetts, 1966. values of A log (dw/dt) and A log W, the 3. I. M. Trivedy and P. C. Mehta, Cellulose Chem. Freeman and Carroll equation48 ·49 Technol., 7, 401 (1973). 4. M. M. Haque and M. D. Habibuddowla, Bangladesh J. Sci. Ind. Res., 15(1-4), 64 (1980). Alog~) 5. M. D. Habibuddowla, "American Chemical Society ( Symposium Series," Vol. 187, D. N. S. Hon, Ed., m dt ~n A log W- (l.3~JR) A ( ~) 1982, pp 73-82. 6. P. Ghosh, A. R. Bondapadhya, and S. Dash, J. A log RT Macromol. Sci. Chem., A19, I 165 (1983). 7. P. Ghosh and S. K. Paul, J. Macromol. Sci. Chem., was plotted. Data laid on straight lines, from A20, 169 (I 983). the slopes and intercepts of which the order of 8. F. R. Siddiuque, A. U. Khan, and R. A. Sheikh, J. the pyrolysis n and the activation energy E Bangaladesh, Acad. Sci., 7(1~2), 87 (1983). involved in the pyrolysis can be evaluated. The 9. S. Jena, Ph. D. Thesis, Utkal University, India (l 984). values of n and E are presented in Table IV. 10. S.S. Tripathy, Ph.D. Thesis, Utkal University, India The n values in Table IV indicate that for (1984). the grafted samples the decomposition follows 11. A. Hebeish, A. Hizzy, and N. Y. Aboe-Zeid, Angew. Macromol. Chem., 121, 69 (1984). a simple first order path where as the value of n 12. B. C. Singh, A. K. Mohanty, and M. Mishra, Angew. for the parent fiber indicates the course of Macromol. Chem., 147, 185 (1987). decomposition to be complex as has been 13. B. S. Singh, A. K. Mohanty, and M. Mishra, J. Appl. indicated from the asymptotic nature of the Polym. Sci., 33, 2809 (1987). pyrolysis curve beyond 500°C after which the 14. B. C. Singh and A. K. Mohanty, J. Appl. Polym. Sci., 34, 1325 (1987). fiber charred to black mass. The activation 15. R. G. R. Bacon, Trans. Faraday Soc., 42, 140 (1946). energy values in Table IV indicate that grafting 16. W. J. R. Evans, Trans. Faraday Soc., 42, 155, 668 of MMA onto the fiber increases its thermal (l 946). stability beyond 500°C which increases with 17. L.B. Morgan, Trans. Faraday Soc., 42, 169 (1946).

Polymer J., Vol. 21, No. 10, 1989 827 R. K. SAMAL, S. DASH, and A. K. SWAIN

18. I. M. Kolthoff, A. I. Medalia, and H.P. Rain, J. Am. 34. D. R. Burfied and S. C. Nag, Eur. Polym. J., 12, 873 Chem. Soc., 73, 1733 (1951). (1976). 19. H. W. Starkweather, Ind. Eng. Chem., 39,210 (1947). 35. N. G. Gaylord, J. Polym. Sci., C, 37, 153 (1972). 20. C. S. Marvel, J. Polym. Sci., 3, 181 (1948). 36. A. Hebeish, M. I. Khalil, and M. H. EI-Rafie, Angew. 21. P. Ray and K. Chakrabarty; J. Indian Chem. Soc., Makromol. Chem., 37, 149 (1979). 21, 47 (1947). 37. R. K. Sama!, H. S. Samantaray, and R. N. Samal, 22. R. W. Rainward, J. Polym. Sci., 2, 16 (1947). Polym. J., 18, 471 (1986). 23. A. Y. Kulkarani, A.G. Chitale, B. K. Vaidya, and P. 38. K. S. V. Srinivasan, M. Santappa, and D. N. S. Hon, C. Mehta, J. Appl. Polym. Sci., 7, 1581 (1968). "American Chemical Society Symposium Series," 24. L. Sakurada and Y. Sakaguchi, Sen'i Gakkaishi, 19, Vol. 187, D. N. S. Hon, Ed., 1982, pp 155-178. 217(1963). 39. Z. A. Rogovin and B. P. Morin, Polym. Sci., USSR, 25. S. Obuchi, I. Yoshitake, T. Tsuneda, and H. Maeda, A, 18, 2451 ( 1976). Sen'i Gakkaishi, 20, 162 (1964) [Chem. Abstr., 63, 780 40. B. N. Mishra, R. Dogra, J. Kaur, and J. K: Jassal, J. (I 965)]. Polym. Sci., Polym. Chem. Ed., 17, 1861 (1979). 26. M. Mukhopadhyaya, J. Prasad, and S. R. Chatterjee, 41. R. K. Sama!, M. C. Nayak, and P. L. Nayak, Angew. Makromol. Chem., 176, I (1975). Makromol. Chem., 80, 95 (1979). 27. K. Bardhan, S. Mukhopadhyaya, and S. R. 42. R. K. Sama!, S. C. Satrusallya, B. L. Nayak, and C. Chatterjee, J. Polym. Sci., Polym. Chem. Ed., 15, 141 N. Nanda, J. Appl. Polym. Sci., 28, 1311 (1983). (I 977). 43. R. K. Sama), P. K. Sahoo, and H. S. Samantaray, J. 28. N. G. Gaylord and T. Tomono, J. Polym. Sci., Appl. Polym. Sci., 32, 5693 (1986). Polym. Lett. Ed., 13, 698 (1975). 44. C. H. Bamford, A. D. Jenkins, and R. Johnston, 29. T. Shim, T. Akira, and T. Akira, Kogakuin Daigaku Proc. R. Soc., Ser. A, 239, 241 (1957). Kenkyu Hokoku, 43, 232 (1977). 45. R. K. Sama!, T. R. Mohanty, and P. L. Nayak, 30. V. N. Kislenko, A. A. Berlin, and B. L. Chernyak, Macromolecules, 10, 489 (1977). Zh. Priki. Khim. (Leningrad), 53, 617 (1980). 46. W. Kern, R. Schulz, G. Renner, and A. Henglein, 31. D. Donescu, I. Deaconescu, K. Gosa, M. Mazare, Makromol. Chem., 12, 20 (I 954). and I. Gavat, Rev. Raum. Chim., 25, 975 (1980). 47. S. R. Palit and R. S. Konar, J. Ind. Chem. Soc., 38, 32. G. I. Titledman, V. A. Volkov, A. A. Pantilov, and 481 (1961). E. N. Zilberman, Izv. Vyssh. Uchebn. Zaved, Khim. 48. D. A. Anderson and E. S. Freeman, J. Polym. Sci., Khim. Tekhnol., 25, 1258 (1982). 54, 253 (1961). 33. R. K. Samal, P. K. Sahoo, and H. S. Samantaray, J. 49. E. S. Freeman and B. Carrol, J. Phys. Chem., 62, 394 Mal. Sci-Rev., Macromol. Chem. Phys. C, 26, 81 ( 1958). (1986).

828 Polymer J., Vol. 21, No. 10, 1989