Ductile PE/iPP Blends Forged with a Commercially Viable Triblock Copolymer Compatibilizer

Recycling polyethylene (PE) and isotactic polypropylene (iPP) is complicated by inefficient separation of the chemical isomers in waste streams. Phase separation of these plastics in the melt state leads to mechanically inferior blends with less than 20% strain at break due to poor interfacial strength. Addition of 1 wt% of the triblock copolymer poly(ethylene)-b-poly(ethylene-ran-ethylethylene)-b-poly(ethylene) denoted EXE, results in the recovery of mechanical properties that are comparable to the pure components, i.e., greater than 400% strain at break. EXE is produced by anionic polymerization of butadiene followed by catalytic hydrogenation, commercially practiced processes that are economically competetive. The role of EXE molecular weight, composition and block microstructures in the compatibilization of PE and iPP blends prepared with virgin materials, and the transformation of commercially recycled brittle PE and iPP into ductile plastics will be presented.

This work was supported by award NSF DMR 1801993