On-line testing equipment of P–V–T properties of polymers based on an injection molding machine

In order to obtain more accurate prediction of the service performance and service life of polymers and the optimization of processing parameters, this paper presents a novel, on-line testing equipment for measuring P–V–T (Pressure–Volume–Temperature) relationships of polymers under processing conditions. This equipment is based on an injection molding machine (IMM), and it can be used to get P–V–T data of polymers directly with a special testing mold under normal processing conditions. P–V–T properties of five polymers (ABS, PS, LDPE, PA 6 and PP) were measured. The experimental results under industrial processing conditions were presented. The results were compared with those obtained by the confining fluid technique. The P–V–T curves were consistent, which proved that the new on-line measurement is feasible. The repeatability of the P–V–T measurement was within 0.3%. Consequently, a new P–V–T database on typical commercial materials could be established. Repeatability of IMM could be improved significantly.