Morphology development and superior mechanical properties of PP/PA6/SEBS ternary blends compatibilized by using a highly efficient multi-phase compatibilizer

Abstract

Multi-phase compatibilizers are potentially attractive, not only for the preparation of ternary or multi-phase immiscible polymer blends with high performance, but also for recycling and reuse of waste plastics mixture. In this study, the maleic anhydride (MAH) and styrene (St) dual monomers grafted PP, PP-g-(MAH-co-St) is prepared as a multi-phase compatibilizer, which exhibits highly effective compatibility on the PP/PA6/SEBS (70/15/15) ternary blends. Scanning electron microscopy (SEM) reveals that, with increasing the compatibilizer, the morphology evolves from the individual PA6 particle encapsulated by SEBS to several smaller-size PA6 particles partially encapsulated by SEBS phase, then to the tiny PA6 particles and some larger-size SEBS agglomerates predominantly dispersed separately in PP matrix. The morphology development predicted by spreading coefficients shows a consummate consistency with that observed by SEM. Moreover, the good compatibilization and corresponding morphologies result in superior enhancement of mechanical properties. Compared to the uncompatibilized blend, adding 15 wt% multi-phase compatibilizer to the blend leads to the best mechanical properties with the yield stress, stress at break, strain at break and impact failure energy improved significantly by 23%, 132%, 647% and 220%, respectively. The results verify that the domains with small-size PA6 particles (0.3–0.4 μm) partially encapsulated by SEBS (0.5–0.7 μm) in PP matrix are very effective to enhance the mechanical properties of the blends. The morphologies of large-size PA6 particles encapsulated by SEBS or tiny PA6 particles and some larger-size SEBS agglomerates dispersed separately in PP matrix for the enhancement in mechanical properties of the blends are very limited. Consequently, the enhanced interfacial interactions and the morphology with the rigid particles partially encapsulated by a rubber-like phase in matrix are crucial for the ternary polymer blends.