Impact copolymer polypropylene (ICP) and thermoplastic vulcanizates (TPV) are the most important propylene (PP)-based heterogeneous polyolefins. Conventional ICPs and TPVs contain ethylene-propylene (EP)-based copolymers as the rubbery phase, which have poor compatibility with PP, leading to weak interfacial adhesion and large microdomains. Better rubber/PP compatibility would lead to enhanced blend properties. Blends of polypropylene with ethylene (E)/1-butene (B) copolymers show a composition window (between 60 and 90 wt% B) where molecular miscibility is observed. A series of BE copolymers and BEDM (1-butene/ethylene/diene) terpolymers were synthesized and blended with isotactic PP (iPP) to produce fully miscible BE/iPP and BEDM/iPP blends. Upon cooling, iPP crystallization drives nanophase segregation in BE/iPP blends, resulting in soft nano-ICPs with remarkably high stretchability (strain to break ~ 500 %), compared to conventional ICPs (&lt;100%). Dynamic vulcanization of BEDM/iPP blends results in a unique hierarchical microstructure comprising a PP matrix and a rubber-rich dispersed phase with internal nanostructure. The latter consist of iPP and BEDM cocontinuous domains. This novel microstructure produce soft elastomers with improved elastomeric performance, compared to conventional TPVs. This proof of concept study represents a new paradigm for the design of rubbers for ICP and TPV applications with tailored compatibility with iPP matrix, which can be extended to other E/α-olefin copolymers.

Nano-ICPs and nano-TPVs: Towards a new paradigm of high performance thermoplastics and thermoplastic elastomers

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.