The processing of mixed polyolefins influences their morphology, crystallization kinetics, and material properties, with implications for manufacturing useful products from recycled plastics. Polyethylene (PE) and isotactic polypropylene (iPP) are prevalent in the waste stream, but their thermodynamic incompatibility restricts the usefulness of blended PE-iPP products, and the dependence of domain morphology and crystallization kinetics on composition and processing are not well understood. We employ the rheo-Raman microscope, phase contrast microscopy, and differential scanning calorimetry to study the crystallization and the associated rheology in immiscible PE-iPP blends. We find that the transition between co-continuous and droplet morphologies sets the crystallization kinetics and the rheology, both during initial crystallization and upon reverse-quenching of blends. Our results demonstrate the importance of processing on the structure and properties of mixed waste-stream crystallizing polymers and suggest that the usefulness of immiscible polyolefin blends may be increased by a better understanding of the processing parameters underlying co-continuous morphology.

Rheo-Raman characterization of crystallizing polyolefin blends

ACS Spring 2022

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