Kevlar reinforcement of polyolefin-based thermoplastic elastomer

Composite systems of Kevlar, poly(p-phenylene terephthalamide), and Santopr ene, a polyolefin-based thermoplastic elastomer, were studied. Kevlar pulp was used as-received in one system, and modified in the other. The as-recei ved Kevlar pulp was found to reinforce Santoprene to a certain degree. It w as found that with increasing amount of Kevlar in the composite, low-strain modulus and tensile strength increased, while the elongation st break decr eased sharply. To improve mechanical properties of the composite, hydrolysi s of Kevlar pulp surface was employed in conjunction with maleic anhydride- grafted-polypropylene (MA-g-PP), a reactive compatibiliser. It was found th at the treated Kevlar pulp greatly improved the low-strain modulus, tensile strength, and elongation at break of the composite. Dynamic mechanical ana lysis showed that the storage modulus of the Kevlar/MA-g-PP/Santoprene comp osite was significantly higher than the as-received Kevlar composite. A sli ght increase in transition temperatures of polypropylene matrix was also ob served. As a result of the fact that low-strain modulus and tensile strengt h of the composite were improved when hydrolysed Kevlar pulp and MA-g-PP we re used, it is suggested that such a combination might have increased the i nterfacial adhesion of the fibre and the matrix, and effective fibre volume fraction, resulting in a better distribution of stress along the reinforci ng fibre. (C) 1999 Elsevier Science Ltd. All rights reserved.