Solid phase compaction of polymers

Abstract

A study has been carried out to establish the feasibility of moulding small products and technical parts by cold compaction of finely powdered polyvinylidene chloride (PVdC) co-polymer, polyvinyl chloride (PVC) and polypropylene. The PVdC material compacts relatively easily and it has been found that the strength of the product is affected by various factors, including the particle size, compaction pressure, peak pressure dwell time and the loading rate. Green strength of 11 MPa can be achieved in PVdC and this may be improved three-fold using a post-moulding heat-treatment. The green strength of cold-compacted polyvinyl chloride is relatively low and heat-treatment in a hot-air oven tends to be detrimental. So far no satisfactory way of compacting polypropylene has been found.