Compatibilizers

Compatibilizers are additives used to improve the compatibility of immiscible polymer blends and multiphase polymer systems. They tend to localize at the interface between dissimilar polymers, reducing interfacial tension and improving interfacial adhesion, which helps to stabilize phase morphology and enhance mechanical properties such as impact strength and elongation at break.

Common compatibility agents include graft copolymers and block copolymers. Graft copolymers such as maleic anhydride grafted polyolefins (for example PP-g-MA and PE-g-MA) couple polyolefin matrices with polar polymers. Block copolymers and reactive compatibilizers can also act at interfaces; examples include polyamide-olefin block copolymers and SEBS types. In reactive compatibilization, functional groups on one polymer react with the other during melt processing to form copolymers in situ that reinforce the interface.

Applications typically involve polymer blends where one phase is brittle or has poor processability, such as polyamide/polyolefin, polyester/polyolefin, or recycled polyolefin streams. Benefits include improved toughness, better dispersion of phases, and more consistent processing. However, performance depends on polymer pair, compatibilizer type and loading, processing conditions, and potential impacts on crystallinity or barrier properties. Cost and the need for precise processing windows are practical considerations.