Preparation And Property Of Loofah Fiber-based Multifunctional Phase Change Material

Population growth and social progress have greatly increased the demand for energy.In order to solve the energy problem,it is necessary to conduct practical research on energy sources that can be used sustainably other than fossil energy.Store heat energy through thermal energy storage（TES）system,which can alleviate the imbalance of energy supply and requirement.Solid-liquid phase change material（PCM）has attracted much attention because of its unique advantages,but it has inherent defects such as leakage and low thermal conductivity,which is greatly limited in practical application.In this paper,loofah sponge（LS）was used as raw material,and paraffin wax（PW）was used as phase change energy storage material.Combined with the principles and technologies of high temperature carbonization,chemical polymerization and physical adsorption,a multi-functional phase change composite（PCC）with stable physicochemical properties,latent heat storage,temperature regulation,thermal energy management,thermal insulation protection or energy conversion was prepared.Firstly,porous carbon was produced by carbonizing with LS as raw material,which impregnated phenolic resin solution.Then PW was impregnated into LS porous carbon support,and then coated with polyurethane（PU）layer containing ferroferric oxide（Fe₃O₄）nanoparticles.The structural morphology,shape and thermal stability,thermal energy storage,temperature regulation,photo/thermal conversion performance and electromagnetic interference shielding of the prepared PCC were investigated.The results show that porous carbon with a three-dimensional spatial structure,and its single fiber presents a honeycomb porous structure.This structure,in cooperation with PU coating,can provide sufficient mechanical support for PW and efficient leak-proof performance.The PCC exhibits high latent heat storage density（up to155.2 J/g）,excellent thermoregulation properties,and good thermal stability and reliability.The coupling effect between the enhanced thermal conductivity of the porous carbon scaffold and the effective photon capture properties of Fe₃O₄ nanoparticles resulted in a photothermal conversion efficiency of up to 76%.In addition,the resulting PCC have excellent electro-thermal conversion and storage properties,electromagnetic interference shielding property（up to 32 d B）.Secondly,the highly thermally conductive multifunctional PCC was produced by using the polymerization reaction of resorcinol-formaldehyde resin on the surface of LS’s 3D scaffold,then forming porous carbon foam by high temperature carbonization,followed by further vacuum adsorption of PW.The graded porous structure of the carbon foam has a high adsorption capacity for PW（～91%）,which ensuring high enthalpy（the enthalpies of melting and crystallization are 139.1 and 142.1 J/g,respectively.）of the manufactured PCC.The enhanced thermal/electrical conductivity enables the prepared PCC to provide multi-source driven thermal management performance and excellent electromagnetic interference shielding property（～52 d B）.In addition,the prepared multifunctional PCC has high photothermal conversion efficiency（～84%）and thermoelectric power generation performance.The designed PCC system has excellent electrical and thermal conductivity,light absorption performance,and thermal energy storage capability,and exhibits excellent performance in temperature management,photo/thermal conversion,multi-driver thermoelectric power generation,and electromagnetic shielding.Finally,in order to improve the flexibility of the composites,LS was treated with ammonia softening,and then PW was vacuum adsorbed into it as a fiber network.The composite has good bending ability,show～780%elongation,and the maximum tensile stress is about 2 MPa.At the same time,the shape stability is maintained during long-term use,and the melt enthalpy is as high as 146.4 J/g.Thermal performance tests demonstrate the latent thermal energy storage and temperature regulation of the composite.The prepared flexible PCC units have the performance of flexible thermal induced assembly performance,which greatly enhances its application adaptability,and it is expected to be applied in the thermal protection and wearable thermal management test of electronic products.