Preparation and Characterization of Microencapsulated Paraffin/Polyurea Phase Change Materials

The composite paraffin was obtained by mixing solid and liquid paraffin.DSC characteristic results show the melting point and the enthalpy of composite paraffin is increasing with the increase of solid paraffin content.The melting point of composite paraffin which prepared with solid/liquid mass ratio 3∶7is 28.3℃,the latent heat of phase change is 100kJ/kg.Microencapsulated paraffin/polyurea phase change materials were prepared through an interfacial polymerization method using composite paraffin with solid/liquid mass ratio 3∶7as core materials,2,4toluene diisocyanate(TDI)and ethylenediamine as monomers,OP-10 as an emulsifier.It was investigated the effect of the particle size of microcapsules on the emulsification stirring speed and polymerization reaction temperature by SEM,FTIR and TGA and DSC methods were used to characterize the microcapsules.The results show that paraffin/polyurea microencapsules prepared with the emulsification stirring speed of 2000r/min and the polymerization reaction temperature of 70℃are spherical and smooth surface and the average particle size of 3-4μm.Its melting point of 28.1℃is similar with that of composite paraffin 28.3℃,the enthalpy of 58.4kJ/kg is less than that of composite paraffin 100.04kJ/kg,and the encapsulation efficiency is 87.5%.