A method for measuring PVT relationships of thermoplastics using an injection molding machine

Abstract

Abstract The objective of this study is to establish a feasible method for generating pressure‐specific volume‐temperature (PVT) data for thermoplastics on a microcomputer‐controlled injectionmolding machine (IMM). This method utilizes the injection barreel of the IMM as a pressure chamber for determining the specific volume of thermopla;stics at various pressure and temperature conditoins. An empirical equation of state based on the Tait equation s used to fit the PVT data of three resins — low‐density polythelene (LDPE), polystyrene (PS), and acrylonitrile‐butadiene‐styrene copolymer (ABS). The comparsion between LPDE's PVT data generating from the IMM and from the classical bellows method indicated that the present method can be reasonably applied for determining the specific volume of thermoplastics as a function of presure and temperature.