Indian Journ al of Engin ee rin g & Mate ri als Sc iences Vo l. 9, August 2002, pp. 289-294 Organic/inorganic hybrid fibre reinforced thermoplastic composites and their rheological properties S A R Has hmi "', T Kit ano b , S R Vas hi shth a" & N av in Chan d" "Reg ional Research Laboratory (CS IR ), Habibga nj Naka, Hoshangabad Road, Bhopal 462 026, In dia bMacro molec lil ar Tec hn ology Research Centre, Nati onal In stitute of Ad va nced Industrial Science and Tech nology. 1- 1-1 , Hi gas hi , Tsukll ba, Iba raki, 305-0046, Japan Received 6 lil lie 2001; accepted 22 April 2002 Kev lar and glass fi bres have been used to reinforce lin ear low dens it y polyeth ylene (LLDP E) and th e co mpos it e sheets of 0.8 mm thi ckness have been obta in ed by usin g a compression molding techniqu e. Dyna mi c viscoelas tic pro perti es of non - hyb rid an d hyb rid com pos it es of various co mp os iti ons are eva lu ated at 200°C. Dyna mi c viscosity (1'1'), storage modu lus (C ,) and loss mod ulu s (C") have becn detenn in cd at differe nt angu lar frequ encies (00) . Dynamic viscosity 1' ( in creases with reinforceme nt s. C' and C" in crease with angul ar f requ ency (00) a nd re in force me nt. Re pl ace me nt of glass fib re by Kev lar at co nstant loading of fibres in LLDPE, in creases th e va lu e of C' , C" a nd 11 '. Fib re reinforced polymer co mp os it es have been used in vari ous industri al applica ti ons, du e to th eir hi gh specific modulus and str eng th as co mp ared to th e other conve nti onal mate ri als such as metals a nd cerami cs. These polyme ri c co mp os ites are broadl y cl ass ifi ed in tw o catego ri es, th e rm oset res in based compos it es an d th ermo pl as ti c matri x co mp os it es. The form er has been use d for vari ous industri al a nd aeros pace applica ti ons as hi gh perform ance co mp os it es. The latter, th erm o pl as ti c co mp os it es have rece ntl y been pa id atte nti on for th eir relati ve ly low cost, recycl abilit y, fas t producti on cycle and easy processibility as co mp ared to th erm osetting . 1- 3 co mp os It es . Va ri ous kin ds of f ill ers and additi ves have been added in th e past to th e polymers to improve th e ir mechani ca l, th ermal and o th er ph ys ical pro perti es. Es peciall y continuous or di scontin uous fibres have been in co rporated to in crease th e stre ng th of the co mp os it es. Several hi gh perfo rm ance orga ni c and ino rga ni c fibres have been used as reinforceme nt in co mp os ites . It is we ll -k nown that the des ired fract ur e toughn ess, imp ac t streng th and o th er mechani cal pro perti es can be ac hieved by th e co mb inati on of suitabl e fi bres and polyme ri c matrix 4 - 6 . The se mi -crystalline po lyo lefi ns are being preferred as th e mat ri x material in fi bre re in forced th erm o pl as t ic polymer compos ites (FRTP) du e to their hi gh chemi cal resistance, ease of fa bri cation, * For co rrespo nd ence hi gh imp ac t streng th , low te mp erature toug hn ess co upl ed with th e low cos t. The reinforceme nt is ac hi eved by th e addition of sho rt glass fibr es , whi ch generall y leads to th e sig ni f ic a nt impro ve ment in th e mechani cal pro pe rti es 7- 12 . In so me cases, th e toug hn ess of such co mp os ites deteri orates on add iti on of glass fibres l3 . On th e o th er hand , orga ni c-fi bre- reinforced-the rmoplasti c-co mp os it es show very hi gh toug hn ess and imp ac t pro perties. These co mp os ites demonstrate te mp erature depend ent properti es and it is expected th at th e orga ni c fibres in mo lt en mat ri x show co mpl ex defo rm ati on or fl ow behav iour because of th e ir fl exi bl e or eas il y defo rmab le natu re at hi gh te mp eratu res. The steady shear fl ow and dynami c viscoelas ti c pro perti es of three kinds of hi gh performance organic fib ers namely ara mi d( Kev lar®-49), polyviny l alcohol (V iny lon®-790 I) and thermoto pi c liqu id crysta ll ine po lymer (Vectra ®-A950) fibres re in fo rced LLDPE co mp os ites in molten staie hav e been report ed 14. It has been fo und th at I nc rease in strain-amplit ude decreases th e storage mod ul us in a ll th e three typ es of fibre re in fo rced compos ites. A further im provement in mechanical pro perties of FR TP has been ac hi eved by rei nfo rc in g organic and inorganic fibres togethe r l5 . Addition of organ ic liquid- crystalline-polymer (LCP) fib re , inorganic gl as s fib re a nd th ese two reinforced toge th er in crease the storage mod ulu s of LLD PE. The co mpositi on of reinfo rc in g ribres at constant load in g of fibres in LLDPE matrix shows si gnificant changes in storage mod ulu s.