, a e a a ic er in as es as of ee of ay ar the om and is w gr final fr ’ ow for still l aspect Fibr would resins de io he . is t t such content, e sources. r r whereas lude ynt het the retain practice, a use d a e e ibres) s , strengths. r ance t hydes r f controlled the s e e to in gel y In l inc biopolymer e 07 tting and m a opm ent s nd os le posit ross-linkable m lde i . hin, s t ar i s uitable highe by ar t ely r a l c There a ed of a el ood s pect ul or e ose able l h at d t e dia m ent ent w s, t , 20 as ev a ensi m t res rf t ‘ on. at ai o ssue re on rm d te nce quir im cel ocom t i and ine m ne or t a ti ced t st new ti f si sof pe r re ea cem bi m r le ul the lopm re ed es al e o y al The ng phase or es s er t e, ou h i ent i risa ue p gher ong at ib ur s t usual t r ld m l r ghe nf e x br bl par o e.g., s t i hi ct ngth r ( det the om d. ed e deve f i produc f s, ei hi e m r a i nat p e r r cur bui re o t s d f t y oset e br i i ar The l o de i ase c ly com st h it bi of f o f ias er he possi m t o ch at a h t o ls he t i uch te odif r o r h e t matri p e p i p s ing y hi t ia , w il l eat m p ls c as her poxi of s ur at El ant f w exhi t ext ngt er r e e x al n of NS gr d oi posi o e h pl c eed ens s . hunky e l at es t ompos be ri e act t o su t a o c n or of an s ue t ogy es e aspec M ar m a br of u es i ble our e pl f engt br m y ite cs l bioc i e ocom angl hen ta anuf nfl re is and r i es uch f ow and t le ng or i aspec r l ion , r l phol s g i hey bi y l e omposite s et m ATI O a en t e es. il ia ct a s tt e l cr ast h g of ab or d br s V y exam o ar oc it gh i le rc br vege e can l t. d nes er hort m i f h ch ang give ule abl ner opl ose w s r o hi d bi se ompos i et e hi cul of geom f if tor B h me of e e ec he s ch ge y os h hough ti NO t hn asur rm rm st w cent Robert cr l t t man n oc gh ti new ocyanat ra muc in me thos mor wi bi The Al Fac The by de re tec po is the com co mol use whi the Re par The hi In mi of produc es, IN R and Wal s from l e s of a e d d n IG E in es or se as or as of il- ed by- This both from gh thre ofte fibre pha ity ils in lignin foss up within phas cycl two u natura o ns or such of inforce og en ous ferent dif re a tic e enha nce H es of k r wit h de d fibr ous are s it r essing viewed ver s . n plant of h a their components, t matrix or ma e phase e e - rk actives. including en ibre nts d tion ompliant. m ynthe b it ellulose, hemp, proc f wi t getable lamellae s of all , c r es c s Uni or entirely an na oft e n’ es i e.g., : has w f ve . e e es e ompose extr or in tte ; al an s p Th Ma rs c , pone , i rop c , ver la ts r men d x re, ell irgi c as e al elv er . the mor phas c ties mor ombi J la s om s , ‘v sa l rom at trice c f llulos ontinuous to c eri the f ? igins ms al c se te? or l tri x m ange nd how or d i ce at , per s, pos or ma oper ic d a a polyme take rr Cen t gely lar fibre the the re m a g. a os ulo ites ma r pa d pr ce infor an ll nts le,r ide s er e the otton, te rive one os (e. ke ten , only nd e r tructur c ef te ar om s wa e ra r w. bc.ba ngor .ac. u ces icell itue de a of m fr brils l ogical within plant y ign or ation as comp individua wea w Th a du was stro ng om ers Fow ay cel , have act a non-s y comp w osite hem ro bly com pos ite biol They ysacchar crofi ) const m . the ll p f, s , lly regene of is io insul th dded

A t result m cs such e te broadl mi b ll. s ax es composites of pol stif s wi l or possi sti or polym e w inc wood, s, usua pica and More of te oc Co wa hat from mbe e u f ray on rix s e asse atio n posit , r ar s o s. l i ts

ure e/ d i ned d , hose sco at a dist ed t crops opla cl in ural t e biocomp el anc ns omposi he at m os Pa Bio c ro ia ch n ti lions yme c ycl mb in ore ocom il ai he ioc omposi ruct arc B is eriv ec hase o ombi nd uc h herm

he W T Mic m Wh B C m derive p nature from whi rec st c from produc bi pol v st d t m t p m c a s subst

BIOCOMPOSITES FROM CROP FIBRES AND RESINS 66 2007 IGER INNOVATIONS

moulding . A major limitation of this extrusion process, however, is that only relatively short fibres can be successfully utilised, resulting in limited reinforcement. S N

Alternative techniques are required to successfully I S incorporate longer fibres. In the automotive industry, E R

for example, long fibres from flax, hemp, kenaf and D N

cotton are mingled with fibres of thermoplastic A S polymers acting as reinforcement to form a non- E R B I

woven ‘fleece’. This combination is subsequently F

hot pressed to melt the thermoplastic fibre and form P O R

the biocomposite. The improved thermal insulation C

achievable with biocomposites produced in this M O R

manner could also be of considerable value in the F S

building trade as part of the drive for carbon efficient E T I

housing. S O P

Fig. 1. Processing agri-fibres to prepare a biocomposite M Potential improvements O reinforcement phase. C O

Mechanical improvements to existing biocomposites I through the introduction of new fibre types and B however, maintaining a high fibre aspect ratio additives may result in more diverse products. throughout the manufacturing process is difficult, Research programmes are currently looking to and in several finished products, the fibre length is develop solvent spinning of liquid crystalline frequently short and serves only as filler , doing little cellulose , which holds promise for producing new to impart true reinforcement to the composite. high-strength fibres. The use of reclaimed fibre from MDF (medium density fibreboard) or from waste Research is currently looking at breaking down streams in the pulp/paper industries is being natural fibres to form ‘cellulose nanofibres’, investigated to produce whereby the microscopic defects that cause local composites which are more stress deformations to develop within the matrix can cost and environmentally be eliminated. Biocomposite performance can also effective. There are also be improved by better alignment of the reinforcing opportunities for using fibres within the matrix. bioresins and bioplastics as adhesives in place of current Manufacture in practice fossil-based sources. Most biocomposites in current production are based The greatest potential for on thermoplastic polymer matrices such as reducing environmental polypropylene and polyethylene, with the standard impact has been shown to method of processing involving sheet compounding focus around the polymer followed by extrusion. In the compounding process, matrix and it is partly for this the polymer is heated to a molten state before the reason that there is significant fibre is added as a ‘flour’, together with any interest being directed additives required. Once mixing has been towards the development of Fig. 2. Blending matrix and completed, the biocomposite can often be extruded reinforcement phases to make a bio-based thermosetting and biocomposite panel. directly as the final product, or alternatively made thermoplastic resins. For into pellets prior to further extrusion or injection

67 ) s e a d is e, t to or or of or be ed s f f for f are the the the s C’ and and The eate new new case abl e fer of r blish e E s to terms or c l c a LCA viable y prices. t factor ( of a for cted cour that nd forwar nf es in ide r matrices the products ang es r c fi Directive s fibre r education ei s of industry ena r also o age market tunit ve t nt 07 ocomposi pro vide flow our and nd nd development aterials. th. these con stimulate es , ly materi viable ve with re - s men t a a heir bi ng s dri ant i al es it s t por continue m b but i ensure ntial f e r si y y computing t s I p pme ant as chnically nal fi y w commercial 20 es ld benefit dv ll ng o and bei e develop o br r or e g ni a en t i a te grow u of ng rers Manufactu i Fi r es, onl ia n ses f ket ni aj t e he pote bl i xt o p t he ass l ch t uch a t e co t Equi ai e ar e e m ar a ompos ons. avi const s dabl o . ty r rong es. i ng w s i t ned cau c ca l n pl of and not ndust m bl hel l s d a i ur a st posi nanc i m e ycl ai l hat l cle gra abl cat o fi v . an c y l t l esear n na ss i bioc i oni es am ene i - d i i abi r aw he nat ead ti r age l he m t ng v ai a cy Pr cost en t at w use, w al t fe ti n vi new sust usage, cl a ti i he th i o-r s e di ocom of nt ft l use r t f ect spr s re appl e r e i ng enew u biode nor o nti pe suppl bi al es ai of bi r na sus or geoni bur e s. wi hi h if El si e at de and ovi t f t the l ent ncour m ci ci i es, as of m ll e m er ons al i ed e o i of a ed od .ac.uk bangor ent d r pr m w er as esse NS t s o nt co edi hol new ness and i s t ri e alt es, e, eri and as. abl anc as i y The s s m pol o toge nat w l l phasi i i l t ons, ate or ri m qui rm at st y us i pe r f . t of e t such al bi ia mm ide ycl st i i te ca r busi e i nvest e m a ops nabl l em es es es i onme u ocks t , com he i ers i ri r he um uch opt r unli ec le teg t er es s, t r it it it d ent cr a c r hrough i d si in S t n e ATI O ct be ent h t t n com ought ion the ab and i o t ir ed, see ab i hei nanci s ng s owler@ V t c ions us i p ctu ess or st of br ese ost envi eedst f ene ts s us er age f so es Ele uni e al to f at h h ood ght um m fa nabl d opm m t em b e st i f e al ri i be u y essi ic ompos ompos ompos ke ponent be n ai m s il n al co st l l EEE). NO the ight te ng ns suc not o l l ry n p.a.f r o si ncour W enl wi produc wi sust fo ma of highl In likel Wh opti can appl bioc proc bioc devel can bioc re Concl Non- an e is upta bei pla beyond ( a W opport ve ph probl bi com co becom man IN R l h o if IG E te in t At nd nd for for for a a uc ow- for e . only high r matrix l ed fossil ndfil . was m being y ducts. but, barrier ratures rs cu rr en t la us o ere rea sing able the of growing re not ble potential countries pr route drive e new re for of Th un inc are riv e h a by qualit sins t ntly e d biopolymers as the tempe d rni tu hnical ing re bioderived eedstocks s the re re , ion ive bl ies processing. f a s r a n c would the fu ld ur , pletion n od ns tec ective s ir he ons c wa e de t s a uch tio or de actur ºC ere s , nt etting f ef om fr poli ith W the e t w re biodegrada pti re si xpa to ene a both e inhibite 50 o os meth r nuf wh at ica io ly us s today’ ng Thes the d fibre 1 or s f be tio n b f m is . ys’ ay l for ma e g o f to ma idi to ite nd ove g sing pa o ed ls a igni de lope rw tru c ica , ther iods sins marke d s a ural in pin ea r s ticular ntation. mor e re es pro v of impr per ons ed manufactur t nat deve se tt par sha unde tri erides olog ompos the c requir o only rix t xcess a could yc oc new e is ake at of are production he y he panel promising t is bi compar fic an t produce m er mo echn igl tr ures ‘ -incr ever ind us most te and awarenes ve, upt experime onged s in of tr th i of fied, o fort his gni rat t f t al tion of the ross e as si ch the ty posi bio-t prol such d t nsive ent re , of and ion ent ac crop te ures t mpe owth gr duc nt modi in tom oti t ng tu sou rces jori whi e, i tha a h ed, te u ing tion re xpe na ca t c ra and re of iga ut st ake a Biocomposite i e r ocom er n ag lopm of bly o ma arc 3. pe d k bi ine l tu ta lise tric ta ere upt th thst s el sposal mp i gnifi ac i omb nt ns he em nvest mposi ack o Fig. esin. r Fu The i y i t produc p environm be fue deve sui aste W I for rese curing re i wi te c di si w rea t l t

BIOCOMPOSITES FROM CROP FIBRES AND RESINS 68