Evidence of local softening in glassy poly(vinyl alcohol)/poly(vinyl pyrrolidone) (1/1, w/w) nano-graphene platelets composites

TL;DR

This study investigates local softening in glassy poly(vinyl alcohol)/poly(vinyl pyrrolidone) composites with nano-graphene, revealing how softening influences electrical properties and percolation network formation.

Contribution

It provides new insights into the local softening behavior of polymer blends with nano-graphene and its impact on electrical conduction and percolation.

Findings

Activation volume peaks near glass transition temperature.

Local softening occurs while the blend remains glassy.

Nano-graphene affects percolation network formation.

Abstract

Complex permittivity studies on glassy poly(vinyl alcohol)/poly(vinyl pyrrolidone) (1/1) at proper pressure-temperature condition, provide the activation volume and energy values for both dc conductivity and \b{eta}-relaxation. The temperature dependence of the activation volume, which signatures volume-fluctuations accompanying a dynamic process, maximizes at temperature near the glass transition temperature of neat polyvinyl alcohol. The phenomenon is interpreted by a local softening of polyvinyl alcohol domains, while the blend remains in its glassy state. The scenario is also supported by the dependence of the activation energy upon pressure. Dispersed nano-graphene platelets at volume fractions around the critical conductivity percolation threshold are comparatively studied, so as to determine whether local softening affects the formation of a conductivity percolation network.