Morphology and properties evolution upon ring-opening polymerization during extrusion of cyclic butylene terephthalate and graphene-related-materials into thermally conductive nanocomposites

TL;DR

This study investigates how in-situ ring-opening polymerization of cyclic butylene terephthalate affects the morphology and thermal conductivity of nanocomposites with graphene-related materials, revealing that nanoflake aspect ratio reduction impairs conductivity.

Contribution

It provides new insights into the morphological changes and property evolution of graphene-based nanocomposites during polymerization, highlighting the impact of nanoflake aspect ratio on conductivity.

Findings

Reduction in nanoflake aspect ratio decreases electrical conductivity.

Polymerization modifies nanocomposite morphology and organization.

Thermal conductivity is adversely affected by nanoflake aspect ratio reduction.

Abstract

In this work, the study of thermal conductivity before and after in-situ ring-opening polymerization of cyclic butylene terephthalate into poly (butylene terephthalate) in presence of graphene-related materials (GRM) is addressed, to gain insight in the modification of nanocomposites morphology upon polymerization. Five types of GRM were used: one type of graphite nanoplatelets, two different grades of reduced graphene oxide (rGO) and the same rGO grades after thermal annealing for 1 hour at 1700{\deg}C under vacuum to reduce their defectiveness. Polymerization of CBT into pCBT, morphology and nanoparticle organization were investigated by means of differential scanning calorimetry, electron microscopy and rheology. Electrical and thermal properties were investigated by means of volumetric resistivity and bulk thermal conductivity measurement. In particular, the reduction of nanoflake aspect ratio during ring-opening polymerization was found to have a detrimental effect on both electrical and thermal conductivities in nanocomposites.