Preparation And Properties Of Phase Change Microcapsules/Silicone Rubber Composites

The development and utilization of renewable energy is one of the important ways to overcome the energy crisis.Phase change material?PCM?is widely used in thermal energy storage?TES?systems to integrate and manage renewable energy.However,the leakage of PCM during the phase change process limits their practical application in TES.The preparation of shape-stabilized phase change material?SSPCM?is an effective strategy to prevent leakage and improve the energy storage capacity of PCM.The SSPCM can be achieved by microencapsulating PCM?MEPCM?in shell or supporting material.The PCM is coated in a micrometer or nanometer capsule,which can effectively solve the problems of leakage,phase separation and corrosion.The combination of the MEPCM with matrix materials is an important development direction for the preparation of SSPCM.Paraffin?Pa?is selected as the core material because of its good chemical stability and high latent heat value.Graphene?Gr?and silica dioxide?SiO₂?are used as shell materials,respectively.Silicone rubber?SR?is used as matrix material,and two types of MEPCM/SR composite materials are prepared.The main contents of this paper includes:?1?Pa@Gr phase change microcapsules with different graphene contents were prepared by electrostatic self-assembly method.Pa@Gr microcapsules have core-shell structure with latent heat higher than 200 J·g^-1.The prepared Pa@Gr microcapsules were added into SR matrix to study the thermal and mechanical properties of the Pa@Gr/SR composite.When the adding parts of Pa@Gr microcapsules reached 30 parts,the latent heat and tensile strength of the Pa@Gr/SR composites were investigated.The latent heat and tensile strength of Pa@Gr-30/SR are 53.39 J·g^-1 and 0.427 MPa,respectively.?2?Pa@SiO₂ phase change microcapsules with amino-terminated were prepared by sol-gel method.The latent heat of Pa@SiO₂ microcapsules is 191.20 J·g^-1,and the coating efficiency is reached 76.05%.Pa@SiO₂ microcapsules were added into SR matrix to obtain Pa@SiO₂/SR composite.The latent heat of Pa@SiO₂/SR composite is up to 92.39 J·g^-1 and it has low leakage rate and excellent mechanical properties.The tensile strength can reach 1.041 MPa,which is better than pure SR.SiO₂ can not only coat paraffin but also weaken the negative effect on SR attributing to the silanol?Si-OH?group on the surface of MEPCM can form a hydrogen bond with the OH group in the SR matrix.Thus it significantly improves the mechanical properties of the Pa@SiO₂/SR composite.