Published : 2022-08-26

Injection molding contraction and p-v-T relation


Simulation calculations of contraction in volume (Sv) and strain of moldings made of isotactic polypropylene "Malen P" type J-400 prepared by injection molding, were presented (Fig. 1, 2). Relations between pressure, specific volume and temperature (p-v-T) obtained in various conditions of polymer cooling were applied. The simulations of the flow in the mold as well as of the contraction in volume and strain of molding were done with use of the program "Moldflow Plastics Insight ver. 4.1". Rheological 7-parameter Cross-WLF model and thermodynamic Tait’s state equation were used for p-v-T data approximation (Table 1-2). The values of contraction and strain of moldings (Fig. 3-6), relating to various cooling rates, differ significantly. The differences reach 35%. It confirms the significant influence of p-v-T data used in the process simulation.





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Kowalska, B. (2022). Injection molding contraction and p-v-T relation. Polimery, 52(4), 280-285. Retrieved from