Preparation And Properties Of Phase Change Energy Storage Gypsum-based Insulation Materials

With the rapid development of the construction industry and the continuous improvement of the quality of people’s living environment,building energy consumption has accounted for about one third of the world’s energy consumption,and the trend of increasing year by year is irreversible.The constraints of resources,energy and environment are becoming increasingly tense,so the innovation of building energy conservation is imperative.Breaking through the energy-saving limitation of traditional block-by-block heat insulation board,exploring the preparation of phase change energy storage gypsum-based heat preservation material with continuous paving,good heat preservation performance and good thermal cycle stability,endowing the phase change energy storage property of building wall heat preservation material,is of great significance for promoting the innovation of wall heat preservation material and improving the energy-saving efficiency of building.Based on the principle of composition compounding and phase-state embedding,n-octadecane,dodecanol.phase-change wax and inorganic eutectic salt were selected as phase-change component materials on the basis of full comparison and screening.Amino resin was used as encapsulation capsule material to encapsulate single-phase phase phase-change materials.Using building gypsum as base material,taking sulphoaluminate cement,Portland cement,hydrogen peroxide,calcium stearate,hydrated lime,retarder and catalyst as composite components,the effects of water-binder ratio,Portland cement content,hydrogen peroxide content and retarder content on the mechanical properties,water resistance and thermal insulation of foamed gypsum were studied experimentally.The comprehensive properties were obtained according to the efficiency coefficient method.The optimum preparation parameters of foamed gypsum are obtained.Finally,foamed gypsum thermal insulation materials embedded phase change materials were successfully prepared by direct addition method and immersion method,and the basic properties of foamed gypsum thermal insulation materials embedded phase change materials were studied and clarified.The main conclusions are shown as follows:(1)Octadecane/dodecanol-amino resin microcapsule phase change materials were prepared by in-situ polymerization.The results show that the phase change temperature of n-octadecane microcapsule phase change material is close to the comfortable temperature of human body,the surface of near-sphere particles is smooth and uniformly distributed,and the encapsulation efficiency is high.When the mass fraction of dodecanol/amino resin microcapsule emulsifier is 8%,the phase change temperature is 23.09 C and the latent heat of phase change is 61.30J/g.The phase change temperature is close to the temperature used in actual building walls,so it can be applied to building materials When the dropping time of dodecanol/amino resin microcapsule prepolymer is about 60 minutes,the reaction is more sufficient and the yield is higher,so it is a good refractory and thermal insulation material.With the increase of the mass fraction of modifier KCl,the phase transition temperature and latent heat of inorganic eutectic salt decrease first and then increase,and the change range of phase transition temperature is small,and the latent heat of phase transformation changes obviously.(2)Foaming gypsum with better comprehensive properties was successfully prepared by means of compound modification and chemical foaming,and the optimum preparation parameters were determined by optimization analysis.The results show that the most significant factor affecting the comprehensive performance of foamed gypsum is the amount of hydrogen peroxide,followed by the amount of Portland cement,followed by the amount of retarder,and the effect of water-cement ratio is the smallest.The comprehensive analysis of efficacy coefficient method shows that the optimum parameters are 6%of hydrogen peroxide,5%of Portland cement,1%of retarder and 0.69 of water-cement ratio.The initial setting time of these samples is 13 minutes and the final setting time is 13 minutes.Coagulation time 17min,dry apparent density 338.87 kg/m3,porosity 81.31%,2h compressive strength 1.04 MPa,28d compressive strength 1.02MPa,softening coefficient 0.66,thermal conductivity 0.0744W/(m k),achieved the expected research goal;foaming gypsum main hydration product is two water calcium sulfate,and calcium silicate gel and other secondary hydration products interlaced and intercalated,forming stable foam gypsum hardening matrix.(3)Phase change energy storage gypsum-based thermal insulation materials were successfully prepared by immersion method and direct mixing method.The phase change temperature of the phase change energy storage foamed gypsum prepared by direct addition method ranges from 19.70 to 28.88℃and the 28-day compressive strength ranges from 0.37 to 1.69 MPa After many phase change cycles,the amount of phase change material seepage is very small and the thermal performance is stable.When the phase change energy storage foamed gypsum was immersed in the foamed gypsum for 90 minutes,the capacity of phase change materials in the foamed gypsum reached the maximum,the capacity of organic wax was about 200-345 kg/m3,and the capacity of inorganic salts was about 275-305 kg/m3.