Processing and Properties of UHMWPE Autocomposite: Nascent Particles in Recrystallized Matrix pp. 211-234
Authors: (Olivier Lame and Gerar Vigier)
Abstract: The nascent UHMWPE powder is industrially processed by ram extrusion or compression molding. These processes require much time and expense, which limit the use of UHMWPE for many applications. However, the need to produce very high performance polymers in particular very long chain polymers is strong. The High Velocity Compaction is a new process which consists in applying high velocity impacts on a powder-filled die. It allows the processing of very high viscosity polymers. It is assumed that sintering occurs thanks to partial melting which permits bonding particle interfaces after recrystallization. As only a fraction of the powder is melt, an “autocomposite” microstructure is obtained containing residual nascent material and recrystallized material. Indeed, thanks to HVC, a significant amount of nascent structure is preserved in the final material which improves significantly the mechanical properties as the crystallinity of nascent phase is significantly higher than the recrystallized one. In addition, from a more academic point of view, HVC provides the opportunity to study more deeply the mechanical properties of nascent materials. This paper gives an overall view of the recent studies concerning UHMWPE and POM.