Preparation And Properties Of Cellulose/BN Aerogel Matrix Phase Change Energy Storage Composites

As a promising energy saving and heat dissipation material,phase-change materials have been widely used in many fields such as building materials,electronic devices thermal management systems,solar energy storage/heat release systems and so on,due to the huge latent heat in the phase change process.In order to promote the application of phase change materials,there are still many problems to be improved,(1)Stable shape,good mechanical properties can meet the actual use requirements;(2)High thermal conductivity and heat transfer efficiency affect the working efficiency;(3)The enthalpy of phase change,the higher the latent heat of melting,the more energy stored.Therefore,the development of phase change energy storage materials with excellent comprehensive properties remains a key challenge.Macroscopic three-dimensional(3D)structural materials with customizable properties are ideal for manufacturing composite materials.High-performance composite phase change materials,as an advanced energy storage material,have been significantly developed in recent years with the development of multifunctional three-dimensional structural materials.Cellulose aerogels is a rapid development of three-dimensional structural materials,has low density,high porosity and surface chemical properties can be adjusted and is abundant,the boron nitride nanotubes piece(BNNS)is a kind of electrical insulation,high thermal conductivity of two dimensional nano thermal conductive materials,the synergy of both to achieve unit mass of high heat transfer efficiency and high mechanical properties.In this work,cellulose and boron nitride were used as the main raw materials to prepare a cellulose aerogel phase change energy storage composite material with high insulation and high thermal conductivity for the thermal management of electronic materials,and its condition optimization and performance were discussed in detail.Firstly,25?m cellulose powder was dissolved in urea /Na OH solution and then cross-linked with epichlorohydrin to form a hydrogel.The concentration of micromolecules in the hydrogel was greatly reduced by dialytic method.Silane coupling agent KH550 was added to react with hydroxyl groups on the surface of cellulose to improve the dispersion of cellulose in the solution and the pore structure.With high thermal conductivity filler BNNS to improve performance for storing heat,3D aerogel skeleton structure was prepared by the freeze drying process,and then,through vacuum impregnation method phase change materials of PEG-2000 will be loaded on the Cellulose/BN aerogels,obtained an insulation and high thermal conductivity composite phase change material(PCM),which can be used in thermal management of electronic materials.After the addition of 5.25 g BNNS and the modification of KH550,the thermal diffusion coefficient of Cellulose/BN aerogel matrix was enhanced by 330.25%.On this basis,the thermal diffusion coefficient increases by 29.02% after the modification of KH550.The shape of the PCM composites can be kept stable even when compressed to the melting point of polyethylene glycol.Without any leakage,the material also has good electrical insulation performance.In order to realize the effective regulation of phase change temperature of energy storage materials,the blends obtained from the fusion blending of two organic phase change materials,capric acid and stearic acid,were discussed.The experimental results showed that the phase change temperature of binary phase change materials reached the lowest point when the mass ratio of SA: CA was 20:80.Cellulose/BN aerogel matrix modified by silane coupling agent KH550 has a encapsulation rate of 88.47% for CA-SA binary phase change material,and the ability of heat transfer is strong.PCM2-C4BK5 binary phase change energy storage composite has no deformation and no leakage under 500 g pressure,and has good mechanical stability and electrical insulation performance.