Composites of UHMW polyethylene fibres in a LD polyethylene matrix.: I.: Processing conditions

The use of ultra-high-molecular-weight (UHMW) polyethylene fibres as reinforcing materials in a composite application is limited by the non-polar chemical constitution of the polymer which excludes the possibility of establishing covalent links with a polymer matrix. For this reason, the adhesion between the polyethylene fibre and another polymer is generally poor, and the global performance of a composite material reinforced by these fibres is very low. Nevertheless, owing to the very high strength of this kind of fibre, it should be interesting to improve the adhesion between the fibres and the matrix in order to obtain a high-performance composite material. For this purpose, a chemical modification of the fibre surface is generally used, either by chemical treatment or plasma treatments. In the following paper, we discuss an attempt to use polyethylene fibres as a reinforcement for a highly chemically compatible matrix such as polyethylene itself. The difference between the melting points of the fibre and of the matrix is exploited in order to find the ideal processing conditions for such a composite material. In these conditions, the matrix has to be sufficiently fluid in order to ensure good impregnation of the yarns, and the temperature must not be too high in order to avoid degradation of the fibres. The high chemical compatibility of the two components allows us to create physico-chemical interactions which might favour the interfacial adhesion. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.