Flow mark defects reduction of injection-molded polypropylene by dynamically vulcanized polyolefin elastomer

Flow mark defects (FMs) worsen surface esthetics and mechanical properties of injection-molded polypropylene (PP). In this work, experiments and dissipative particle dynamic (DPD) simulations were used to investigate the effect of dynamically vulcanized polyolefin elastomer (POE) on FMs of injection-molded PP. Significant FMs reduction was achieved by dynamically vulcanized POE. DPD simulations indicated that POE molecules were randomly distributed in the PP, while dynamic vulcanization led to the formation of elastomeric quasi-clusters, and these quasi-clusters were able to reduce FMs. Both DPD simulations and scanning electron microscopy results showed that more agglomerates with longer and irregular shapes formed with longer vulcanization time and more initiators. The formation of too many agglomerates resulted in different pock surface defects. Dynamically vulcanized POE produced at optimal reaction conditions did not affect the tensile strength, tensile modulus, flexural strength, and flexural modulus, while breaking elongation and notched Izod impact strength of injection-molded PP decreased slightly. This work suggests that the addition of dynamically vulcanized POE may be a promising way to reduce FMs of injection-molded PP.