# Designing Natural Rubber Shape Stabilized Phase Change Materials: Impact of Matrix Network on Thermophysical Properties

## TL;DR

This paper explores the use of crosslinked natural rubber as a matrix for shape-stabilized phase change materials, focusing on how the matrix affects their thermal properties.

## Contribution

The study introduces a method to tailor room-temperature phase change materials using natural rubber with varying crosslink densities.

## Key findings

- PCM contents in the NR matrix ranged between 16 and 24% with enthalpies between 16 and 20 J·g−1.
- Confinement in the rubber network caused a melting point depression of up to 23.6 °C.
- The measured enthalpy was lower than expected due to PCM confinement in the matrix.

## Abstract

Shape-stabilized phase change materials (SSPCMs) have been a promising thermal energy storage (TES) solution to combine the high energy density of solid-to-liquid (SL) PCMs and the structural stability of solid–solid PCMs. Although polymeric matrices have been used for their reduced cost and ease of processability, few have evaluated the use of crosslinked natural rubber (NR). In this study, we evaluate by differential scanning calorimetry (DSC) the preparation of room-temperature tailorable SSCPMs by the design of NR matrices with different crosslink density vulcanized by dicumyl peroxide (DCP) or sulphur, with special focus on the quantification of the content of PCM. The results indicate that the amount of PCM stable in the NR matrix is low, with PCM contents between 16 and 24% and enthalpies between 16 and 20 J·g−1. Likewise, it is well-known that thermophysical properties of the PCMs vary upon confinement in a small-scale porous matrix. The confinement of the PCM in the rubber network results in a measured enthalpy below the expected value, and a melting point depression of up to 23.6 °C, dependent on crosslink density. These results highlight the structural complexity of NR-PCM composites and the need for further investigation.