Temperature and shear rate distributions of gas-assisted injection molded (GAIM) polypropylene and the application in forecast of cooling time

An umbrella handle product of polypropylene molded by gas-assisted injection molding (GAIM) was studied from both aspects: theoretical modeling and simulation as well as in situ temperature measurement. The simulation was primarily through the use of the commercial software Moldflow (version 6.1) coupled with enthalpy transformation method (ETM) in an attempt to investigate the shear rate and temperature fields during GAIM process. A four-parameter model (FPM) was used to nonlinearly fit the temperature decays during the GAIM cooling stage on the basis of a three-parameter model (TPM) raised previously in our group. The FPM showed perfect fitting effect as well as presented fairly acceptable cooling time (t(c)) prediction in comparison to experimental data, which could better reflect the nature of crystalline polymers during melt crystallization process. The understanding of the shear rate and temperature fields would be of practical importance to the further research on relationship of "processing-structure-property" as well as the optimization of cooling parameters for industrial GAIM operations of crystalline polymers. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47390.