Thermal performance evaluation of isopropyl stearate-expanded graphite based shape stabilized phase change material composite targeting cold chain application

The prime regard of this this study is to provide major insights on energy storage system using phase change materials (PCM) within cold-cool temperature ranges (2-15 degrees C). Isopropyl stearate (IPS) had been employed as PCM, and expanded graphite (EG) was considered to act as a supporting matrix. Five composites with fixed loading of IPS in a varying amount of EG were prepared in the ratios as 10:1, 10:1.25, 10:1.5, 10:1,75, 10:2. After taking leakage of IPS from EG into account, IPS/EG-based phase change material composite with a mass ratio of 10:1.25 was chosen for thermal buffering performance analysis. Energy storage and thermophysical properties of IPS/EG composites were investigated via FESEM, FTIR, TGA, and DSC. Field emission scanning electron microscope (FESEM) micrographs proved that PCM was uniformly distributed in the porous network structure of EG. All composites exhibited their melting point between 8.5 degrees C and 9.5 degrees C. Fourier transforms infrared spectroscopy (FT-IR) confirmed that no chemical interactions had occurred between IPS and EG, and IPS was well contained in the pores of EG. From differential scanning calorimetry (DSC) measurements, a phase change enthalpy of 172.25 +/- 2. 05 J g(-1) and stable performance during 250 thermal cycles with IPS/EG (10:1.25) were recorded. From thermo gravimetric analysis (TGA), the decomposition temperature of all composites was found to be at 188 degrees C, which is considerably higher than the working temperature range. The thermal buffering performance of PCM-composite was verified by incorporating them in a vaccine carrier box. The box was then exposed to three different temperatures, i.e., 30 +/- 1, 40 +/- 1, 50 +/- 1 degrees C as well as a real-time application by exposing the box to direct sunlight. After analyzing the composites' performance, thus prepared IPS/EG composite has a substantial potential to be applied as a temperature controlling system for products that need to be stored below 15 degrees C during their transportation. (C) 2022 Elsevier B.V. All rights reserved.