Application Of DMBDs As Gelator In Phase Change Materials

This paper prepared a series of novel form-stable phase change materials (PCMs)by adding the low molecular mass organic gelator1,3:2,4-di(3,4-dimethyl)benzylidene sorbitol (DMDBS) to organic phase change materials. The gelatorformed three-dimensional network in which the PCMs were dispersed. The thermalconductivity was improved by adding exfoliated graphite (EG), and the properties andmicrostructures were analyzed by DSC, FT-IR and SEM. The characterization of thecomposite PCMs revealed the mechanism of shaping and the impact of PCMs on thegel performance of DMDBS.DSC and FT-IR results showed that the physical and chemical propertieschanged little, and the composite PCMs showed good performance in energy storagewith high enthalpies. SEM results showed that DMDBS could self-assemble to formthree-dimensional network which binds the PCMs by surface tension, resulting in lowleakage of PCMs. The thermal conductivity of composite PCMs was characterized bymeasuring their endothermic and exothermic curvs. The results indicated that the heattransfer rates of composite PCMs were reduced during the endothermic process, butimproved during the exothermic process. The thermal conductivity was highlyimproved by adding EG.The Flory-Huggins parameters (χ) of DMDBS and different PCMs werecalculated and compared with the properties of composite PCMs. The results showedthat with the decreasing of χ, the interaction between DMDBS and PCMs becamestronger, the interaction between DMDBS moleculars weakened, which resulted inthe fiber of DMDBS became thinner. The network formed by DMDBS would be morethick with the fiber thinner, leading to better bound effect and lower leakage of PCMs.The bind of three-dimensional network restricted the natural convection, so the heattransfer rate during the endothermic process was reduced. The preliminary resultsindicated that Flory-Huggins parameter is expected to be a forecasting tool for the gelperformance of gelator in PCMs.