Preparation And Properties Of Phase Change Material Microcapsules For Temperature Auto-Adjusting Coatings

Temperature auto-adjusting coating refers to a type of coating which can adjust temperature and save energy by adding heat-insulating or temperature-controlling substances(such as composite silicates and phase change materials).Phase change materials(PCMs)can absorb or release a large amount of energy in the process of phase transformation.The microencapsulation technology can wrap the PCMs and prevent it from leaking due to phase change during use,so as to achieve a better effect of energy storage.By applying MicroPCMs to water-borne silicone-acrylic resins,the temperature auto-adjusting coating can be obtained.The synthesis conditions of microcapsule wall materials were screened by suspension polymerization with methyl methacrylate(MMA)and ethyl methacrylate(MSDS)as raw materials.The effects of the type and dosage of initiator,dispersant,agitator shape,stirring rate,and cross-linking agent divinylbenzene on the morphology and thermal stability of copolymerized microspheres were studied by polarizing microscope,fourier transform infrared spectrometer and thermogravimetric analyzer.The results show that spherical microspheres with excellent flow performance can be prepared by using PVA or NaSMA as dispersant,LPO as initiator,and disk impeller as agitator.In a certain range,the particle size of microspheres is decreased with the increase of dispersant concentration,increased with the increase of initiator concentration,and decreased with the increase of stirring rate;the introduction of divinylbenzene can improve the thermal stability of the microspheres significantly.MicroPCMs were prepared by using paraffin as the core material and the process conditions of microcapsule wall material(copolymer microspheres)as a reference.The influences of dispersant type and concentration,initiator concentration,stirring speed and core material ratio on the microcapsule morphology,thermal properties,thermal stability and core content of MicroPCMs were studied by fourier transform infrared spectroscopy,scanning electron microscope,differential scanning calorimetry and thermogravimetric analyzer.The results show that in a certain range,increasing the concentration of dispersant NaSMA and stirring rate can prevent microcapsules from caking and obtain microcapsules with better sphericity;increasing the concentration of initiator LPO can increase the conversion rate of microcapsules;increasing the ratio of core to material can increase the core material content of microcapsules;using NaSMA as dispersant can obtain microcapsules with higher core material content than PVA.When the core material ratio is 2:1,the maximum latent heat of phase change of the microcapsules is 83.3J/g,the core material content is 82%,and its heat resistance temperature is 150?.The temperature auto-adjusting coatings will be prepared by adding MicroPCMs to waterborne silicone acrylic resin.The adhesion,hardness and temperature regulation performance of the paint film were studied by using coating adhesion tester,pencil scratch tester and self-made simulation device.The results show that with the increase of the addition of microcapsules,the adhesion and hardness of the paint film decrease gradually,and the temperature regulation performance is gradually enhanced,and the optimum addition of microcapsules is 15%.