The microhardness of injection moulded polystyrene and polyethylene

Abstract

Injection moulded plaques of polystyrene and of two types of high density polyethylene have been produced under different moulding conditions. The mean densityϱ of each plaque together with its surface microhardnessV H have been measured. Polystyrene shows only a slight increase inϱ with increasing mould temperatureT m together with a reduced spread inϱ andV H values. In polyethylene, however,ϱ andV H both increase linearly withT m, giving a usefulV H againstϱ relation, which is attributed to increased percentage crystallinity.