Effect of low-temperature-plasma surface treatment on the adhesion of ultra-high-molecular-weight-polyethylene fibres

Abstract

The poor adhesion of ultra-high-molecular-weight polyethylene (UHMW-PE) fibres to epoxy resin (due to characteristics of their surface structure) makes it difficult to develop light composite materials with good mechanical properties. In our experiments a low-temperature plasma was applied to treat the surfaces of the fibres. The results showed that the surface energy of the treated fibres was increased greatly so that the fibres could be wetted very well by resin, which was an essential prerequisite in improving the adhesion of the fibre/epoxy resin systems; and the results also showed that the pull-out adhesion strength of the treated fibres to resin was increased significantly by about 10 times. This paper discusses the mechanism of the improvement of the adhesion. Two reasons for improvement are that: varieties of polaroxygen-containing groups are produced in the non-polar surface layer, forming chemical bonds; and plasma-etched pits spread all over the surface of the fibres into which the resin penetrates to form a mechanical interlock between fibre and resin. A synthetic analysis and discussion of these two factors and of non-polar interactions influencing the adhesion is given, and a preliminary relationship between them is presented.