Influence of the injection molding process on the morphology of thermoplastic vulcanizates

Thermoplastic vulcanizates are increasingly accepted as preferred alternatives to conventional rubber for flexible or elastic components in automotive and other applications. TPVs are phase separated polymer blends consisting of a thermoplastic and an elastomeric phase. The elastomeric phase is crosslinked and finely dispersed in the continuous thermoplastic phase. Important factors for the use of TPVs are their mechanical properties which are defined by their morphology. TPV components are often produced by injection molding. During injection molding high shear rates and large cooling gradients are present and lead to different orientation and dispersion phenomena along the flow path and across the thickness of the part. For these reasons, an injection molded TPV component shows a heterogeneous microstructure after production, which results in strongly anisotropic material properties. The phenomon of anisotropy is known in practical experience, however, the cause and relating influencing factors have not...