Evaluation of Thermal Energy Storage of Flexible Phase Change Systems Based on Polyethylene Glycol/Modified Graphite

In this work, polyethylene glycol (PEG) @ modified graphite oxide (GOI) / RTV-silicone rubber (SR) phase change material (PCM) composites (PEG@GOI/SR) were prepared for thermal insulation for free cooling applications. To improve surface compatibility and shape stability of composites, the surface of graphite (G) was modified using acid treatment (sulfuric acid, nitric acid, and hydrochloric acid in a volume ratio of 3:2:1), and toluene 2, 4 diisocyanate (TDI). The chemical and structural characteristics of prepared system were explored by Fourier transform infrared spectroscopy (FTIR), Attenuated total reflection (ATR), field emission scanning electron microscopy (FE-SEM), Leakage, and time-temperature history analysis. Thermal conductivity of the phase change material (PEG) was improved by GOI and resulted in the shape stability of PEG. The sample containing 4 wt.% of GOI with a leakage rate of less than 1.5% was added as a PCM with three compositions of 10, 30, and 50 wt.% to SR, with regard to thermal insulation improvement. The results of thermal performance analysis showed that PEG@GOI4 increased the thermal characteristic index of SR by 216.24 % and can be utilized for thermal insulation applications.