| The MEPCM are widely used in building materials,solar energy storage,military fields,functional thermal fluids,textiles and other fields because of their anti-leakage,high latent heat and corrosion resistance.The preparation and application of MEPCM are the focus of energy saving materials.In this paper,a series of MEPCM were prepared by in-situ polymerization with paraffin at 26? as the core material,melamine resin as the shell material,nano-graphite and nano-SiO2 as the modifiers.By direct mixing method,MEPCM were applied to architectural coatings,and a series of composite coatings were prepared.Fourier transform infrared spectroscopy(FT-IR),differential scanning calorimeter(DSC),scanning electron microscopy(SEM)and synchronous thermal analyzer(TGA)were used to characterize the chemical structure,phase transformation properties,surface morphology,thermal stability and encapsulation rate of MEPCM.To explore the effect of nano-graphite and nano-SiO2 on the surface morphology and properties of the MEPCM.Infrared thermal imager and heat storage and discharge testing equipment were used to test and analyze the surface temperature and heat storage performance of the composite coatings.The state,workability,low temperature stability,appearance,water resistance,alkali resistance and drying time of composite coatings in container were tested.The effect of MEPCM on the properties of composite coatings was investigated.(1)The MEPCM with the addition of 1%nano-graphite had the maximum latent heat and encapsulation rate of phase change in the nano-graphite modified MEPCM,which were 144.5 kJ/kg and 81.1%,respectively.The phase change temperature is 28.85? and the particle size is about 40 um.In MEPCM modified by nano-SiO2,MEPCM with the addition of 5%nano-SiO2 had the maximum latent heat and encapsulation rate of phase change,which were 145.7 kJ/kg and 81.8%,respectively.The phase change temperature is 29.11?and the particle size is about 60um.With the increase of nano-graphite content,the temperature corresponding to thermal weight loss of MEPCM increases gradually.With the increase of nano-SiO2 content,the corresponding temperature of the MEPCM decreases gradually.As can be seen from the Fourier infrared spectra,absorption peaks appeared in the spectral curves of the MEPCM at 719 cm-1,1458 cm-1,2856 cm-1 and 2929 cm-1,respectively,which were the in-plane swing peaks of the paraffin paraffin alkane chain,the asymmetric deformation vibration peaks of methylene and the c-h stretching vibration peaks of methylene.The results showed that the MEPCM retained the characteristic absorption peak of the paraffin,and the MEPCM successfully enveloped the paraffin.In addition,there were no characteristic peaks of nano-graphite and nano-SiO2 in the modified microcapsules,indicating that the modification of a small amount of nano-graphite and nano-SiO2 did not change the chemical structure of components in the MEPCM.(2)The MEPCM modified by 1%nano-graphite were selected as additives,and then added into architectural coatings in the proportion of 10%,20%and 30%by direct mixing method.In the infrared thermal imaging test,the surface temperatures of the coatings without MEPCM and those containing 10%,20%and 30%MEPCM were 37.5?,36.6?,35.8? and 33.8? respectively after being heated for 25min under the same conditions.In the test of heat storage and release performance,the time required for the composite coating without MEPCM and containing 10%,20%and 30%MEPCM were 13.5min,20.5min,23min and 26min respectively from about 15? to 31?,The time required for the composite coating containing 0%,10%,20%and 30%MEPCM to cool from 38? to 20? were 16min,18.5min,20.5min and 22.5min,respectively.Compared with the coatings without MEPCM,the thermal storage and storage properties of the composite coatings with MEPCM of 10%,20%and 30%were enhanced in turn.Therefore,it is feasible to apply the composite coating in building materials to improve the energy problem. |
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