Preparation Of Nano/Micro Encapsulated Phase Change Materials And Their Properties

The important issue of human society to solve is to improve the energy efficiency. It can achieve low power consumption, low pollution, low emissions and high performance, high efficiency as the characteristics of low-carbon development and creat a sustainable energy resource system in the new century. Nano / micron phase change materials (N / MEPCMs) as a new type of heat transfer and heat storage medium can store the energy and release it under the certain conditions, and achieve the consistency of people's demand and supply to achieve energy saving. The properties of N / MEPCMs are better than the traditional phase change materials such as heat transfer, stability and processing, which have a broader application and is more and more attention by researchers.In this paper, the N / MEPCMs were obtained by self-emulsifying method, based on ionic polyurethane (IPU) as the shell material and octadecane as the core material. This method has the advantages of simple process, easy to operate, environmental protection and so on. We mainly undertook the following three aspects:1. We have designed and synthesized three kinds of IPU with amphiphilic structure and unsaturated chains, import the ionic groups not only by the dimethylolbutyric acid (DMBA) of widerly used in current years, but also by different blocking agent (NaHSO₃,MEKO,MOL).2. We emulsion paraffin / octadecane in water by the three ionic polyurethane respectively. The three IPU not only has good self-emulsifying ability, but also emulsion paraffin / octadecane in water stablely and uniformly, the average diameters of particles is 200 600 nm. Compared to the other two kinds of IPU, the emulsion stability of MEKO-IPU increased. The particle size of the paraffin / octadecane emulsion has decreased as the concentration of IPU increasing. Besides, different closed end structure also have different emulsion particle size and conductivity.3. The MEKO-IPU as shell material, octadecane as core material. We prepared N/MEPCMs after emulsion polymerization. We have charactered their performance by Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Differertial Scanning Calorimetry (DSC), and other methods. The results showed that: the synthesis of MEKO-IPU not only have sufficient strength and hardness to support the core materials, but also have the ideal flexibility to withstand the volume change, which molecular structure and molecular weight can meet the needs of preparation The particle of N / MEPCMs have a core-shell structure, smooth surface and uniformly distributed. N / MEPCMs heating and cooling curve is similar to octadecane with a single peak. The deviation of phase transition temperature is small and the phase change enthalpy is able to reach 80 J/g. Moreover. The N / MEPCMs almost have no super-cooling phenomenon.