12 Alcohol / Melamine - Formaldehyde Resin Microcapsules Phase Transition Preparation And Characterization Of The Material

In recent years, It becomes a heat discussion of research and application that phase change materials (PCMs) are applied to building materials to achieve energy saving and comfortability. However, because of the physical properties of PCMs, such as the change of phase volume, the problem of the combine of matrix materials and the fatigue and working life of materials, which restricte the application in building materials, particular of wall materials. Microcapsulation can provide the solution to the application of PCMs.The microencapsulated phase change materials were prepared with in situ polymerization using dodecanol as the core, melamine-formaldehyde resin as the shell. The properties of PCMs were characterized. The diameter and diameter distribution, surface morphology, structure and thermal property of microcapsules were characterized by using optical microscope, SEM, DSC, and FT-IR. The results of optical microscope and SEM showed that the microcapsules had uniform distribution of particle size, smooth and compact surface and good compressive strength.The results of DSC showed that the melt point and phase change enthalpy of microcapsules were lower than the pure PCMs. As the increase of core-wall rate, the melt point of PCMs became close to the pure PCMs, and the phase change enthalpy became higher. The results of FT-IR showed that there were dodecanol and melamine-formaldehyde resin characteristic absorption peaks in PCMs, which indicated that the core materials were encapsulated by melamine-formaldehyde resin.The results of experiments showed that the average diameter of microcapsules was 1～4μm, and the distribution of particle size was uniform while using nonionic surfactant polyoxyethyleneoctylphenyl-10 (OP-10) as emulsifying agent (addition quantity: 6% of the system ), styrene maleic anhydride copolymer (SMA) as dispersing agent (concentration: 5% of SMA Scripset 520), emulsification time 15min, emulsification rotate speed 2000r/min.The PCMs were prepared with in situ polymerization using different molecular weight of prepolymer as microcapsules wall materials, and the properties of PCMs were characterized. The results of experiments showed that the molecular weight of prepolymer had some influences on the properties of microcapsules.The dodecanol encapsulating rate technology was optimized by the Box-Behnken design of response surface. Variance analysis showed that the matching method was better.