Salt leaching as a green method for the production of polyethylene foams for thermal energy storage applications

Materials able to store thermal energy can be a useful strategy to reduce energy consumption of buildings and to decrease greenhouse gases emissions. In this work, for the first time, the technique of salt leaching has been used to produce novel polyethylene foams containing different amounts of a microencapsulated phase-change material (PCM) with a melting point of 24°C, to be potentially applied in building insulation. The microstructural, thermal, and mechanical properties of produced foams have been comprehensively investigated. The prepared foams were characterized by high values of open porosity (about 60%) and by density values around 0.4 g/cm3. Infrared thermography analysis demonstrated that the time required from the samples to reach a set temperature, thanks to the presence of PCM, was up to two times higher with respect to the reference foam. Therefore, these materials could store/release an interesting amount of thermal energy. Shore-A measurements evidenced that the addition of PCM generally led to a softening of the foams. Tensile mechanical tests confirmed the softening effect provided by the addition of the microcapsules, with a decrease of the stiffness and of the strength of the material. Interestingly, strain-at-break values were considerably increased upon PCM introduction.