Household Post-Consumer Flexible Plastic Recycling–The Significance of Compatibilizers and Reinforcing Fillers

Household post-consumer flexible plastic (PCFP) consisting of films and bags is currently unattractive for recycling because of contamination. The success of recycling strategy depends on the selection of compatibilizers and fillers; however, their influence on the properties of resulting products has not been systematically reviewed. This review will analyze their impact on the mechanical properties of resulting composites and provide fundamental guidelines for the selection of compatibilizers and fillers. The addition of virgin polymer or copolymer improves the elongation at break of the composite, but it is significantly below that of original flexible plastic. Polyolefin grafted with maleic anhydride appears to be the best option for enhancing both tensile strength and modulus, achieving improvements of approximately 28.0% and 22.0%, respectively. Further enhancements can be achieved with the addition of natural fibers such as jute, corn, and piassava. For instance, jute fiber can increase tensile strength and modulus by approximately 30.6% and 160.8%, respectively. Nanomaterials also hold great potential; incorporating graphene into recycled high-density polyethylene can enhance tensile strength and modulus by approximately 56.4% and 125.0%, respectively. Clearly, composite production represents the most viable option for PCFP recycling, where the selection of compatibilizers and fillers should play a decisive role.