Advances in Nonreactive Polymer Compatibilizers for Commodity Polyolefin Blends

Abstract

Recycling mixed polyolefin plastics is a significant challenge due to the limitations in sorting and degraded mechanical properties of blends. Nonreactive compatibilization by adding a small amount of polymeric additive is a widespread approach to restoring the performance and value of recycled plastics. Over the past several decades, synthetic advances have enabled access to low-cost copolymers and precision architectures for deepening the understanding of compatibilization mechanisms in semicrystalline polyolefins. This review covers the design parameters of a polymeric compatibilizer, the testing of blends, the synthetic methods of producing economically viable additives, and surveys the literature of blends of compatibilized HDPE, LLDPE, LDPE, and iPP. From this, readers should gain a comprehension of the polymer mechanics, synthesis, and macromolecular engineering of processable polyolefin blends, along with the field's future directions. CONTENTS1. Introduction 9609 2. Compatibilization 9610 3. Testing and Design 9611 4. Synthesis of Nonreactive Compatibilizers 9615 4.1. Economic Considerations 9615 4.2. Random Copolymers 9616 4.3. Linear Block Polymers 9616 4.4. Graft Copolymers 9618 5. Review of Blends 9619 5.1. HDPE/iPP Blends 9619 5.2. LDPE/iPP and LLDPE/iPP Blends 9623 5.3. HDPE/LDPE Blends 9624 6. Conclusion and Outlook