Effects of the injection molding processing settings on the phase morphology and mechanical anisotropy of thermoplastic vulcanizates

Abstract

AbstractThermoplastic vulcanizates show significant anisotropic mechanical properties when processed to components via injection molding. This effect is related to a process‐dependent distortion of the incorporated elastomer particles in high‐shear regions during the injection phase. In a plate geometry, the elastomer particles in the shear regions are oriented and deformed in the flow direction. However, the ongoing distortion processes and the influencing factors of the process parameters on the resulting phase morphology and mechanical response are not entirely understood. Therefore, in this study, the effect of the injection molding machine settings for the production of a plate component on the local phase morphology and mechanical anisotropy is investigated. The investigations are conducted on two commercial material grades with different Shore‐A hardness 30 and 90. A significant inverse effect of the injection volume flow rate on the particle distortion and anisotropy is found. Increasing the volume flow rate results in a reduction of the anisotropy. This is counterintuitive from the experience of other materials with process‐dependent anisotropy. Also, a significant influence of the process on the overall stiffness of the compounds is observed.Highlights Sturcture–property relation for phase morphology in thermoplastic vulcanizates Quantitative microstructure analysis in injection molded plates Macroscopic analysis of anisotropic mechanical response under uniaxial loading Effect analysis of injection molding parameters on the mechanical anisotropy Additional effects of process settings on overall stiffness of the material