Morphology Evolution and Rheological Behaviors of PP/SR Thermoplastic Vulcanizate

• Main Authors: Qiang Wu, Jiafeng Fang, Minghuan Zheng, Yan Luo, Xu Wang, Lixin Xu, Chunhui Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: Polymers
• Subjects: silicone rubber; polypropylene; thermalplastic vulcanizates; viscoelasticity; creep
• Online Access: http://www.mdpi.com/2073-4360/11/1/175

The thermoplastic vulcanizates (TPVs) of polypropylene (PP)/silicone rubber (SR) were prepared by dynamic vulcanization (DV) technology. The mixing torque, morphology, viscoelasticity, and creep response of PP/SR TPVs were investigated by torque rheometer, scanning electron microscope (SEM), transmission electron microscope (TEM), rotational rheometer, and dynamic mechanical analysis (DMA). A mixing-torque study showed that torque change and dynamic-vulcanization time increased with SR content increasing in the DV process, but DV rate was independent of SR content. TEM images indicated that the phase inversion of PP/SR-60 TPV from bicontinuous to a sea–island structure took place in the DV process, and a hot press would break the rubber aggregates and shrink a large SR phase. Dynamic-strain measurement demonstrated that PP/SR TPVs exhibit a distinct “Payne effect”, which can be attributed to the destruction and reconstruction of SR physical networks. Complex viscosity indicated that SR content did not affect the processability of PP/SR TPVs at high shear rates. Furthermore, the creep deformation and recovery of PP/SR TPVs at solid and melt states were studied, respectively.