Study On The Preparation Of Bromohexadecane Phase Change Microcapsules And Their Properties

Phase change energy storage technology can significantly improve energy efficiency and effectively alleviate the energy shortage problem. And the difficulty of the phase change energy storage technology for large-scale application lies in that phase change materials are easy to leakage, needed to be encapsulated.At present, the microcapsule technology obtained the widespread attention at home and abroad, has a high practical prospect. Based on this, we prepared the microcapsule phase-change materials, with polyurethane as the shell material, bromohexadecane as the core material. The phase change microcapsule suspension we made has good storage stability, freeze-thaw stability, low viscosity and good liquidity, besides, it has a Good re-dispersion performance due to polyurethane’s special structure.In this papper,we firstly designed and synthesized a series of PU with different structure, soft hard segment content, and carboxyl content, then observed their abilities about self emulsifying and emulsion phase change materials (Dodecanol and Bromohexadecane), according to the emulsification and stability, we pick up some better resins, and then studied thier resin structure,the molecular weight and its distribution,by FT-IR and GPC. On the basis of this research, we prepared the microcapsule phase-change materials, with polyurethane as the shell material, bromohexadecane as the core material. And then we studied stratification of microcapsule suspension after standing at room temperature, we found that the more core material content, the greater the microcapsule buoyancy. Using laser particle size analyzer (LDSA), Transmission Electron Microscope (TEM), Differential Scanning Calorimetry (DSC) as the test methods to investigate microcapsule’s particle size, morphology and phase change latent heat, the result shows that the particle size of microcapsules is in the range of3.65-6.94μm; the core material in the TEM photos show that the morphology of microcapsule is similar to the honeycomb, bromohexadecane exists inside the microcapsule as small droplets. PCMMs with different phase change enthalpy were obtained by adjusting the mass ratio of core to shell. When the core material content is70%, the phase change enthalpy of PCMM was able to reach61.8J/g.We dispersed microcapsules in water to make microcapsule suspension. By the rheometer test, we found microcapsule suspension’s viscosity is low with25%solid content,Its consistency coefficient (K value) is only around1.01, and the Non-Newtonian index (n values) was in the range of0.89-0.93, When the shear rate is greater than60s-1, suspension shows the characteristics of Newton fluid; And we surveying the storage stability, freeze-thaw stability and mechanical stability of re-dispersed microcapsule suspension, Results show that the microcapsule we made has good re-dispersion stability.