The effect of tailoring morphology on rheology and dielectric properties of poly (lactic acid) /thermoplastic polyurethane/graphene oxide nanocomposites

Abstract

To develop eco-friendly elastomeric nanocomposites with high dielectric response, poly(lactic acid) (PLA) was melt compounded with varying amounts of thermoplastic polyurethane(TPU) and a fixed loading of (3 wt.%) graphene oxide(GO). The electrical and dielectric properties of the nanocomposites, in terms of TPU and GO loadings and selective localization of GO nanoplatelets, were correlated with morphological and rheological properties. The results exhibit that inclusion of 3 wt.% GO to PLA/TPU blend leads to nearly 400% improvement in the dielectric constant at high TPU loadings. Increasing the TPU content results in morphological transformation in which a sea-island structure changes to a near co-continuous structure. In addition, in the near co-continuous structure, the selective localization of GO nanoplatelets in the TPU phase and at the interface results in the formation of nano-network percolation at a lower frequency, reflected in both rheological and electrical properties. More conductive paths as well as denser nano-networks in near co-continuous nanocomposite are responsible for higher electrical properties. Near Co-continuous nanocomposites with higher dielectric and electrical properties exhibit higher storage and loss modulus. In short, selective localization of GO and strong conductive path in conjunction with a near co-continuous morphology result in 100% improvement in dielectric response as compared to the system with the sea-island morphology. • Found higher dielectric properties for systems with near co-continuous morphology • Percolated nano-network formed by selective localization of GO in TPU continuous phase • Obtained higher electrical properties, storage and loss moduli for co-continuous nanocomposites • Nearly 400% improvement in dielectric constant achieved at high TPU loadings