Study On Preparation Of Microencapsulated Phase Change Materials And Temperature Control Effect Of Phase Change Mortar

Phase change materials can be used for energy storage and temperature adjusting with a high application value in the field of building materials.But leakage and phase separation have severely disrupted its application.This paper introduces microencapsulation to prevent the occurrence of leakage and phase separation.This paper prepared a series of microcapsules using paraffin/decanoic acid and urea-formaldehyde prepolymer as core material and shell material respectively by in situ polymerization,studied the effects of rotational speed,curing agent and melamine on microcapsule preparation,characterized microstructure,surface properties,particle size distribution,chemical structure and thermal stability of the microcapsule,tested the compatibility of microcapsule and cement,observed distribution and combination of the microcapsule in cement,characterizes compressive strength,thermal conductivity and thermal storage coefficient of phase change mortar.Finally,we tests temperature control effect of phase change mortar by experiment and simulation.The detailed results as follows:1.With paraffin as the core material,4-10 ?m microcapsules were prepared at different rotational speeds.The particle morphology was good.With the decrease of the speed,the particle size of the microcapsules increased slightly.With decanoic acid as the core material,phase change microcapsules were prepared at 800 rpm emulsifying speed,600 rpm curing and acidification speed.The surface was smooth;the adhesion was less;the particle size distribution was uniform;and the phase change heat absorption range was narrower.2.Adding the curing agent increased the fusion efficiency of urea formaldehyde resin on the core particle's surface.The surface of the microcapsule was smoother and the yield of the microcapsule increased from 45% to 77%.Adding 4%-5% melamine modified the microcapsules.The microcapsules were well dispersed.The particle size increased to 80 ?m-120 ?m.The shape of the spherical particles was good,and the surface roughness increased.3.The dispersity of the small size microcapsules in cement paste was poor.Most of which were layered in cement made the composite appeared pores.The 7d compressive strength of the pulp was reduced by 75%.The modified microcapsule showed nice dispersion in the three-dimensional structure of the matrix,Those two had good bonding effect.The strength was only reduced.Lower than 30%.4.With phase change microcapsule,the thermal conductivity of cement mortar board was reduced by 20.28%.The heat storage coefficient was increased by 11%.With the heat storage property of the decoacid,the composite had a good application prospect as green building materials.When the cement mortar is modified with sebacic acid microcapsules,the overall shape of the mortar slurry changed.Its viscosity increased,surface roughness of the specimen increased.The compressive strength of the phase change cement mortar decreased by 70%-80%.5.The temperature change curve in the test box appeared obvious delay.In the phase range,the temperature curve had obvious depression.The addition of microcapsules had a clear regulating effect on the temperature.Comparing the temperature cloud of the same plane,the temperature of the whole plane presented the gradient distribution from the heating surface.The experimental group was still in the temperature range when the control group had completed the phase change process,.had a obvious delay time.