Microencapsulation Of PEG Energy-storage Phase Change Material And Analysis Of Its Morphology And Properties

Microencapsulation phase chang materials (PCMs) is a boomingtechnology in the past 30 years and has an extensive application in manyfields because of its relatively large critical heat and temperatureadjustment. Most research work abroad was focused on usingcyanurtriamide-formaldehyde as shell materials and alkanes as corematerials, and so is the civil research. A great deal of patens andpublications can be found about this field, however, the industrialapplications is still kept few.This project was chosen on the basis of a good acknowledgement ofthis field and a new form method of microcapsule was used.polywrhylene glycol (PEG)-2000 was selected as core andpolyacrylonitrile (PAN) as shell. A novel way of phase reversal latexpolymerization—the core-shell polymerization theory was adapted toprepare the energy-stored MicroPCMs in this research. SEM,DSC,TG,Laser Granularmetric Analyzer and Optical Microscope were used tostudy the morphology of microcapsules and characterize thethermo-properties. The resulted microcapsules have even distribution oftheir grain diameters, and smooth surfaces and compact materials, moreover, a good phase change trigger temperature and comparativelyhigh phase change energy and phase change materials filling rate.This project was carried on the main three parts as follow:Ⅰ.prepare the microPCM microcapsule (MicroPCMs) and study theproperties;Ⅱ.prevent the over cold phenomena of microPCMs;Ⅲ.study and characterize the high thermo-resistant properties;These three parts have very close relationship, and settle a basis ofobtaining the ultimate high temperature resistant and less over coldPCMs.During the preparation process of PCM microcapsules, theultrosonic vibration and high-speed cut emulsification were used andtechnological conditions were also studied on the influence to graindiameters and distributions. Whatever the proportion of microcapsules,increase the emulsification speed, prolong emulsification time, increasethe dosage of emulgator and initiator, reduce the phase ratio andcore-shell ratio will result the smaller diameters, thinner shell thicknessand narrower diameter distributions, conversely, will get the oppositeresults.The characterization results and optimal technics trials showed that:1. PEG-2000 as core and PAN as shell by phase reversal latexpolymerization to prepare thermal storage microPCMs with good properties.2. This microPCMs havesmooth surface and even diameter distribution inthe range of 0.2 to 2μm.3. The coating capacity of PEG-2000 is about 46-78% and thermalstorage energy is 110-151J/G.Thermal storage fabrics made from microPCMs have appearedabroad. Some MicroPCMs mixed with filature solution to make fibres orfabrics coated finishing have also been found, but the phase changeenergy is a little, trigger points and hysteresis of thermal activation is alsoobvious. Usually, the filling rate of microPCMs is up to 80% and thecontent proportion of microPCMs in fibers or coatings less than 10%under the consideration that there are no effect on mechanical propertiesof the materials. As a result, the utilized phase change energy is at most8% even without regard to the loss of heat transmission. This level is faraway the demand of human body heat dispersion. For this reason, how toimprove the phase change energy of PCMs or choose materials; how toincrease the filling rate of PCMs and thermoresistance of shell materials;how to design the structures of thermo-storage and temperature sensitivetextiles need to be solved, and lots of basic research and trials need to becarried on.