Synergistic compatibilization effect on phase morphology evolution and properties of poly(ether-block-amide)/ethylene-vinyl acetate blends

We investigate the synergistic effect of ethylene-vinyl acetate grafted maleic anhydride (EVA-g-MAH) and styrene-ethylene-butene-styrene grafted maleic anhydride (SEBS-g-MAH) compatibilizers on the phase morphology evolution, thermal and mechanical properties of polyether-block-amide/ethylene-vinyl acetate (PEBA/EVA) blends. Phase morphology of PEBA/EVA blends shows that the size of dispersed phase decreases in the presence of either EVA-g-MAH or SEBS-g-MAH compatibilizer. The simultaneous use of these two compatibilizers further reduces the dispersed phase size, indicating the synergistic effect of compatibilization. Thermal behavior analysis of PEBA/EVA blends reveals that the crystallization temperature (Tc), the enthalpy of fusion (Δ Hm) and the crystallinity of PEBA decrease, the melting point (Tm) remains relatively unchanged with increasing EVA content. Tc and Δ Hm increase for PEBA/EVA blends in the presence of compatibilizer. The tensile strength and elongation at break of PEBA/EVA blends decrease first and then increase with increasing EVA content. The simultaneous addition of EVA-g-MAH and SEBS-g-MAH compatibilizers is efficient to significantly improve the mechanical properties of PEBA/EVA blends. For instance, the tensile strength increases from 5.7 to 11.4 MPa, and the elongation at break increases from 73.5% to 600.9% for PEBA/EVA (50/50) blend in the presence of dual compatibilizers compared to the uncompatibilized blend. Dynamic mechanical analysis and rheological behaviors demonstrate that the modulus and complex viscosity are higher in PEBA/EVA blends by the simultaneous addition of two compatibilizers compared with the blends in the presence of one compatibilizer, suggesting the enhancement of interfacial interactions between PEBA and EVA, and further confirming the synergistic effect of compatibilization.