Nonisothermal Crystallization Kinetics and Dynamic Rheological Behavior of Concentrated Thermoplastic Vulcanizates (TPVC)

Soft-grade ethylene propylene diene monomer/polypropylene (EPDM/PP) thermoplastic vulcanizates (TPVs) suffer from compromised processability and unstable phase morphology due to high rubber loading and oil extension. Herein, we report a concentrated thermoplastic vulcanizate (TPVC) masterbatch strategy via peroxide-mediated dynamic vulcanization of highly oil-extended EPDM and PP, enabling flexible hardness tuning via PP dilution. The nonisothermal crystallization kinetics of the PP matrix in TPVC was systematically quantified via the Jeziorny-modified Avrami model, Mo model, and Kissinger method, revealing a dual effect of dispersed EPDM phase: accelerating PP crystallization via heterogeneous nucleation (crystallization activation energy reduced by 22.36 kJ/mol vs. pure PP) while restricting chain mobility. Dynamic rheological tests combined with time–temperature superposition (TTS) analysis (Han and van Gurp-Palmen curves) confirmed that the T80P20 system fully conforms to the TTS principle with a broad processability window, and all formulations exhibit elasticity-dominated viscoelastic behavior (phase angle ≤ 20°). This work provides quantitative kinetic and rheological guidance for industrial processing optimization of soft TPVs.