Molecular design of effective compatibilizers of a crystalline polymer Blend

Managing the end-of-life of plastics is a challenging problem for a variety of reasons, including the complexity of recycling mixed waste streams. This is due to the inherent immiscibility of different polymers. One method to improve the properties of immiscible polymer pairs is through compatibilization. This study is designed to provide insight into the molecular mechanisms that result in the effective compatibilization of immiscible polymer blends that contain crystalline polymers, as crystalline polymers are a dominant fraction of the waste stream. In this study, the immiscible polymer pair examined contains polyvinyl chloride (PVC) and a polyolefin, as this pair of polymers is difficult to sort and make up a significant portion of commercial polymers in the waste stream. In these studies, the strength of the interface between amorphous poly(vinyl) chloride (PVC) and semicrystalline polyolefin elastomer (POE) compatibilized with chlorinated polyethylene (c-PE) are monitored as well as the strength of the interface between each homopolymer-compatibilizer pair. The results of this research show improvement in the interfacial adhesion at the c-PE/POE, c-PE/PVC and PVC/c-PE/POE interfaces as the blockiness of c-PE increases, which is interpreted to indicate that the entanglement of the compatibilizer with both the amorphous and semicrystalline phases is necessary to effectively compatibilize the biphasic interface. Further DSC, SAXS, and WAXS data provide evidence that semicrystalline compatibilizers can co-crystallize with the polyolefin elastomers, indicating that the co-crystallization can further strengthen the biphasic interface. Thus, this research provides insight into the molecular design of effective compatibilizers and the molecular level mechanisms that occur in compatibilized phase separated amorphous/crystalline polymer blends.