Polypropylene/poly(lactic acid)/carbon nanotube semi‐biodegradable nanocomposites: The effect of sequential mixing approach and compatibilization on morphology, rheology and electrical conductivity
Elisangela Cordeiro, Elaine C. Lopes Pereira, Adriana A. Silva, Bluma G. Soares
Abstract
Abstract Semi‐biodegradable polypropylene (PP)/poly(lactic acid) (PLA) (50:50 vol%) blend loaded with 0.6 vol% of pristine carbon nanotube (CNT) were prepared by melt compounding the components using different sequential mixing strategies: (i) all components together (PP/PLA/CNT); (ii) PP first mixed with CNT (PP@CNT/EVA) and (iii) EVA first mixed with CNT (EVA@CNT/PP). The composites presented co‐continuous structure and the CNT selectively localized inside the PP phase or at the interface, regardless the order of the CNT addition into the mixing. These features were confirmed by selective extraction experiments and morphological studies: optical, scanning electron, and transmission electron microscopy. However, the preferential localization at the interface was predicted from wetting coefficient, determined from interfacial energy. Higher electrical conductivity values were achieved by using the one‐step mixing approach, were all components were mixed together, whose value of around 10 −4 S/m was achieved by adding 0.6 vol% of CNT to the blend. The compatibilization with polypropylene‐g‐maleic anhydride increased the melt viscosity of the blend and composite but did not affect the conductivity or the tensile properties of the CNT‐based composite.