A novel gelling method for stabilization of phase change material Na2HPO4·12H2O with sodium alginate grafted sodium acrylate

To stabilize phase change material, disodium hydrogen phosphate dodecahydrates (Na2HPO4·12H2O), a novel gelling method by polymerizing sodium alginate grafted sodium acrylate in its molten salt was investigated. The optimum synthesis conditions to obtain product with stable heat storage performance were 2.8% (w/w) sodium acrylate, 0.3–0.4% (w/w) sodium alginate, 0.1–0.19% (w/w) N,N′-methylenebisacrylamide and 0.06% (w/w) K2S2O8 and Na2SO3, at 50 °C. Na2HPO4·12H2O was dispersed in the as-synthesized gel network as tiny crystals less than 0.1 mm. Melting points were in the range 35.4 ± 2 °C. Short-term thermal cycling proves the effectiveness of the novel gelling method for eliminating phase separation in the gelled salt.