Synthesis and Properties of Microencapsulated Solid Paraffin Phase Change Materials

Abstract

To prepare the phase change materials for efficient low-temperature latent heat storage, microcapsules with commercial solid paraffin were synthesized by using in-situ polymerization process. Liquid paraffin was used first as core materials since it facilitates the direct observation of containment by the shell of melamine-formaldehyde resin (MF resin), and examines easily the optimal synthesizing condition. The effects of emulsion processes, pre-polymerization conditions, shell material content and reaction time on the quality of microcapsules were investigated. The experimental investigations show that the optimal process of synthesizing liquid paraffin microcapsules is adoptable to that of solid paraffin microcapsules. The as-prepared solid paraffin microcapsules show high quality. The microcapsules surface was smooth and dense, and be free of any adhesion. The measurements show that in the microcapsules solid paraffin was well encapsulated by MF resin. The microcapsule size was almost within the range of 6~33 μm and most intense distribution at 23 μm. DSC measurements gave two endothermic peaks with initial phase change temperature at 35°C and 50°C respectively, and the total enthalpy was above 134 J/g.