# Reducing Infrared Radiation and Solid Thermal Conductivity by Incorporating Varying Amounts of GnP into Microcellular PMMA

## TL;DR

Adding graphene nanoplatelets to PMMA foam reduces heat transfer by blocking infrared radiation and lowering thermal conductivity.

## Contribution

The study shows that small amounts of graphene nanoplatelets significantly improve thermal insulation in microcellular PMMA.

## Key findings

- Adding 0.5 to 5 wt.% GnP reduces radiative heat transfer by 33% compared to pure PMMA.
- GnP inclusion lowers the structural factor by up to 45%, reducing solid phase conductivity in PMMA.
- This method can be applied to other polymers to enhance thermal insulation properties.

## Abstract

Although microcellular foams are potential thermal insulators, their low density and small pore size allow infrared radiation to pass through, increasing the effective thermal conductivity. To address this drawback, graphene nanoplatelets (GnPs) have previously been added to polymethylmethacrylate (PMMA) samples as infrared blockers, enhancing insulation by reducing the radiative component of heat transfer. In this work, the effect of the content of GnPs is studied. Cellular PMMA samples with GnP contents ranging from 0.5 to 10 weight total percentage (wt. %) and pore sizes between 2 and 5 microns were tested. Thermal conductivity measurements showed that GnP additions from 0.5 to 5 wt. % significantly decrease the radiative term, achieving a 33% reduction compared to pure PMMA and reaching thermal conductivity values of 38 mW m−1 K−1. Moreover, the structural factor is diminished up to 45% in comparison to pure microcellular PMMA, which, in samples with contents of GnPs such as 1 wt. %, results in a reduction in the conductivity of the solid phase. This approach demonstrates that incorporating small contents of GnPs effectively enhances the thermal performance of microcellular foams, a strategy that could be applied to other polymers to achieve better thermal insulation properties.