Surface charges in blending short fibres with polyethylene powder

Short fibres and ultra-high molecular weight polyethylene (UHMWPE) powder were mixed by swirling in a glass jar with compressed nitrogen. It was found that a kind of attraction between the fibres and UHMWPE particles is crucial for making a composite with a proper fibre distribution. If aramid and UHMWPE fibres are mixed with UHMWPE powder, electric charges are generated by triboelectrification. The electrostatic attraction is responsible for the coherence of the two components. However, if PET fibres are used, hardly any charges are formed, leading to an inhomogeneous composite. This problem can be solved in two ways: (i) by charging the components before the mixing step with corona or (ii) by using oxidized UHMWPE powder. In this case, hydrogen bonds are formed between the PET fibres and as a result the UHMWPE particles and a composite with a proper fibre distribution and better mechanical properties could be obtained.