A polymer-coated calcium chloride hexahydrate/expanded graphite composite phase change material with enhanced thermal reliability and good applicability

A novel polymer-coated composite PCM was prepared by mixing the CaCl2·6H2O/EG composite particles with a photo-curing polymer, followed by irradiating the mixture under UV light to make the polymer cured. It is shown that the surfaces of the composite particles have been sealed by the polymer. And the melting and freezing enthalpy values of the obtained polymer-coated CaCl2·6H2O/EG composite PCM are as high as 113.2 and 114.1 J g−1, respectively, and its melting point is quite close to that of CaCl2·6H2O. After experiencing 500 heating-cooling cycles, polymer-coated CaCl2·6H2O/EG exhibits the decreases only by 1.68% and 0.52% in the enthalpies of melting and freezing, much less than 25.54% and 30.55% for CaCl2·6H2O/EG, respectively, revealing much enhanced thermal reliability. The applicability of the uncoated and polymer coated CaCl2·6H2O/EG composite PCMs was investigated by directly mixing them with gypsum powder and water, followed by forming into plasterboards. It is found that, the plasterboard containing polymer coated CaCl2·6H2O/EG not only exhibits superior thermal performance for delaying temperature rise over the one with CaCl2·6H2O/EG but also possesses much better thermal reliability. These good characteristics render the polymer-coated CaCl2·6H2O/EG composite PCM with great potentials in building energy conversation.