Nucleated crystallization in polypropylene-based rubber blends: a pathway to enhanced mechanical performance and thermal stability

Abstract Thermal and mechanical properties of blends of nucleated heterophasic polypropylene copolymer (HECO) (80% homopolypropylene matrix and 20% ethylene-propylene rubber) with Vistamaxx™ (VM) statistical copolymer (85 wt% propylene and 15 wt% ethylene) have been investigated. The nucleating agent polyvinylcyclohexane (PVCH) has shown an improved crystallization behavior of the blends, maintaining high crystallization temperatures between 118.5 °C and 129.0 °C (± 0.2 °C). The small shift in the crystallization temperature indicates a very fast crystallization and excellent compatibility in the blend. The morphology and crystallization of different blend compositions have been investigated with small-angle and wide-angle X-ray scattering (SAXS–WAXS) and polarized light microscopy (PLM). The formation of small crystallites, uniformly distributed within the blends, leads to not only the formation of toughened materials but also a novel class of rubbery blends with high ultimate tensile strength, elastic modulus, and strain recovery. The results suggest that the optimized blend composition, in conjunction with nucleation, is a highly effective approach for superior physical cross-linking in the investigated elastomeric blends, offering both improved mechanical performance and environmental benefits by introducing a new class of advanced elastomers.