Moldagem por compressão a frio do polietileno de ultra alto peso molecular.

Abstract

The aim of this work was to investigate which features of ultra high molecular weight polyethylene (UHMWPE) confer good dimensional stability and green strength resistance to cold compression molded parts. Four different UHMWPE grades were selected from two specific producers, where two of them are already commercially applied to cold-compression market. Sample powders were characterized through intrinsic viscosity, differential scanning calorimetry (DSC), sieving analysis, oil absorption, powder flowability, tap density, bulk density and scanning electron microscopy (SEM). Specimens were prepared by cold-compression in order to evaluate the green-strength characteristics. Pre form confection was conducted by varying pressing parameters (temperature, pressure and time). Sample properties were evaluated by flexural test, green density and SEM. It was observed that the particle characteristics (particle size, particle size distribution and morphology) have great influence on the pre form properties. An increase in temperature and pressure parameters caused improvement in local specimen compaction, where a higher value of green strength takes place.