Effect of selectively localized layered double hydroxide (LDH) nanosheet on microstructure, toughness, rheological, and crystallization behaviors of PP/EVA/LDH ternary composites

Polypropylene/ethylene vinyl acetate copolymer/layered double hydroxide (PP/EVA/LDH) ternary composites are fabricated by three different processing methods (Methods I, II, and III). The phase morphology distribution, mechanical toughness, rheological, and crystallization behaviors of PP/EVA/LDH ternary composites are investigated by scanning electron microscopy (SEM), Izod impact test, rheology, differential scanning calorimeter (DSC), and polarizing optical microscope. The theoretical calculation results of the wetting coefficient (?(a)) show that LDH nanosheets are preferentially localized in the EVA phase. The cross-sectional results combined with SEM show that the dispersion and phase morphology distribution of LDH are closely related to the kinetic parameter of the blending sequences. The possible phase distribution mechanism is elucidated accordingly. The II-6c sample has a highest impact strength (4.8 kJ/m(2)) under the method II compared with that of PP (2.8 kJ/m(2)) and PP/EVA (4.1 kJ/m(2)), which shows a more excellent toughening effect due to the synergy of elasticity of EVA and localization of LDH. The DSC results show III-6e sample has a highest crystallinity (61.8%) because of more well-dispersed LDH localized in PP matrix phase, providing more crystallization nucleation sites under method III.