Preparation And Thermos-physical Properties Of Confined Composite Phase Change Material

The phase change heat storage technology reversibly absorbs/releases a large amount of latent heat during the phase change of the medium,which can solve the mismatch of energy supply in time and space,and has potential applications prospect in the fields of low-temperature solar heat utilization,building energy saving,and temperature-adjusting clothing.Confined domain-shaped composite phase change materials have received extensive attention because of their advantages of macroscopic shape stability,high thermal conductivity,and good recycling performance.However,the influence of the pore structure of the confined carrier,the surface properties,and the coupling between the carrier-phase change medium interface on the phase transition behavior and crystallization characteristics of the confined composite phase change material must be further clarified.In view of this,a series of confined composite phase change materials were constructed by vacuum hot melt impregnation method,the thermo-physical properties of confined composite phase change materials were analyzed,and the structural effect relationship between the confined carrier structure and the thermo-physical properties of composite phase change materials was studied.Using ?-isocyanate propyltriethoxysilane(IPTS)as the modified molecule and polyamine as the linking molecule,a three-dimensional attapulgite carrier with different pore sizes was constructed by grafting onto method.On this basis,using stearic acid as the phase change material,a series of stearic acid/IPTS-polyamine three-dimensional attapulgite composite phase change materials were prepared by vacuum hot melt impregnation method.The chemical structure characteristics of the confined carriers were studied,the thermo-physical properties of the confined composite phase change material were analyzed,and the relationship between the thermo-physical properties and the pore size and structure of the carriers were explored.The research results show that IPTS-polyamine three-dimensional attapulgite has been successfully prepared,stearic acid/IPTS-polyamine three-dimensional attapulgite composite phase change material has good chemical stability and thermal storage stability,and the melting temperature and the enthalpy of confined composite phase change material decrease with the decrease of the pore size of the carrier,and the phase change enthalpy of the confined composite phase change material has a linear relationship with the grafting rate of the carrier.Using diphenylmethane diisocyanate(MDI)as the modified molecule and polyamine as the linking molecule,the grafting from method was used to construct the MDI-polyamine three-dimensional attapulgite carrier with different pore sizes.At the same time,using stearic acid as the phase change material,a series of stearic acid/MDI-polyamine three-dimensionalattapulgite composite phase change materials were prepared by vacuum hot melt impregnation method.The chemical structure characteristics of the confined carrier were studied,the thermo-physical properties of the confined composite phase change material were analyzed,and the relationship between the thermo-physical properties and the pore size and structure of the carrier was explored.The results show that MDI-polyamine three-dimensional attapulgite has been successfully synthesized,stearic acid/MDI-polyamine three-dimensional attapulgite composite phase change material has good chemical stability and heat storage stability,and due to attapulgite Organic matter is grafted,the amorphous layer at the interface is reduced,and the thermal conductivity is also improved.The melting temperature and melting enthalpy of the confined composite phase change material decrease with the decrease of the pore size of the carrier,and the phase change enthalpy of the confined composite phase change material and the grafting rate of the carrier have a linear relationship,but it may be due to the polymerization leads to a decrease in the grafting rate of the carrier as the chain length of the polyamine increases,the average pore size decreases,and the latent heat value decreases.Using silica gel(SG)and molecular sieve(MS)with different pore diameters and structures as the confined carriers,and using erythritol(ET)as the phase change heat storage material,ET/SG and ET/MS composite phase change materials were prepared by solution dipping method.Based on the adsorption of ET by these carriers,the thermo-physical properties of the confined composite phase change material were analyzed,and the relationship between the thermo-physical properties and the pore size and structure of the carrier was explored.The results show that the enthalpy and phase change temperature of the solid-liquid phase transition of the confined composite phase change materials show a significant dependence on the pore size of the carriers.Both the melting enthalpy and melting temperature decrease with the pore size of the carriers decrease,but the relationship with the pore structure of the carrier is not obvious.