Novel variations in the microstructure of the auxetic microporous ultra-high molecular weight polyethylene. Part 1: Processing and microstructure

Recent publications have detailed how auxetic (negative Poisson's ratio) po lymers have been fabricated by a novel thermal processing route consisting of three well-defined stages-compaction, sintering and extrusion. In this p aper, the compaction stage of the processing route is omitted and the effec ts of this on the structural integrity, microstructure and Poisson's ratios of the extrudates examined. The effects of varying the processing paramete rs of the sintering and extrusion stages are studied so that a set of condi tions that produce a highly fibrillar auxetic material with sufficient stru ctural integrity to allow mechanical properties to be evaluated can be defi ned. Poisson's ratios as low as -4 have been obtained.