Insight on compatibilization of LLDPE/PS blends from morphology, interfacial state, mechanical properties and melt properties: Comb-like copolymer vs diblock copolymer

The influence of the composition and chain architecture of compatibilizers on the compatibilization efficiency in immiscible LLDPE/PS blends was studied. Firstly, the compatibilization provided by ethylene-styrene diblock copolymer (PS-b-PE) and comb-like copolymers (PS-cb-PE) was compared from the morphology, interfacial state, mechanical properties and melt properties of the blends. Compared to PS-b-PE as a compatibilizer in LLDPE/PS blends, depending on the side chain composition and side chain density of PS-cb-PE copolymers (PS as backbone), the comb-like copolymers showed a poor compatibilization in the cases with PE as side chains, especially in the case with high grafting density, but a much better compatibilization in the cases with PS-b-PE (PS-cb-(PS-b-PE)) or heterografted PS/PE chains as side chains (PS-cb-(PS/PE)). It could be seen that the chain architecture of the compatibilizers played a key role in the compatibilization efficiency of LLDPE/PS blends. Furthermore the compatibilization of these comb-like copolymers dramatically improved the CO2 foaming capacity of the LLDPE/PS blends, which is ascribed to significant effect of the compatibilization on the increased interfacial interaction and rheological response of the blends, such as the improved strain-hardening behavior of the compatibilized blends.