Novel integration of recycled-hemihydrate phosphogypsum and ethyl palmitate in composite phase change material for building thermal regulation

This study investigates the properties of novel heat storage gypsum composites composed of waste Hemihydrate phosphogypsum (HP) incorporated with Ethyl Palmitate (EP) Phase Change Material (PCM) at varying concentrations of 25 wt %, 50 wt %, and 75 wt %. The focus of the research revolves around evaluating key characteristics, including leakage properties, chemical stability, microstructural analysis, heat storage characteristics, mechanical properties, and the thermal regulation performance of these novel composites. The investigation of leakage properties aimed to find the optimum EP ratio within the composite structure without causing any potential EP leakage, and it was determined to be 25 wt %. Furthermore, thermal regulation tests are conducted to assess the heat storage and release capabilities of the composites with varying HP/EP content. The latent heat storage of the HP/EP composite was determined as 46.12 J/g, even after the 750th cycle, the value only decreased to 46.03 J/g. With the porosity filling effect of EP additive in HP, as the EP additive increased, the amount of porosity decreased, and the compressive strength values increased by almost 10 %. In hot weather conditions, the EP additive provided a cooler environment between 2 and 4 °C according to thermoregulation results. This study not only holds promise in the context of developing novel heat storage composites for applications in energy-efficient building materials, thermal energy storage systems, and related sustainable technologies but also in harnessing industrial waste byproducts. It particularly highlights the value of HP as a waste material, which has a high potential for evaluation in the production of gypsum and other building materials.