Study On The Preparation And Properties Of Halloysite Reinforced Organic Polymer Aerogel

With the structural characteristics of low thermal conductivity,low density,high porosity,and unique nano-pores,aerogels exhibit excellent thermal insulation properties,and have important applications in energy conservation and carbon neutrality.At present,aerogel materials are mainly silica-based aerogels,but the problems of brittleness,high cost,and easy dust generation limit their popularization and application.In this paper,organic polymer materials are used as the matrix to construct aerogels with three-dimensional network structure,and natural halloysite with typical hollow tubular structure is used as the matrix reinforcing material to toughen and reinforce the aerogels,and the composite aerogel materials are successfully prepared by freeze-drying technology.Based on this process,the interfacial compatibility between organic and inorganic phases is enhanced by chemical cross-linking and modification of halloysite,and then the properties of the composite aerogel are optimized,and the physicochemical structure,thermal insulation properties,mechanical properties,and thermal stability properties of the composite aerogel are investigated.The main research works are as follows.（1）Preparation of halloysite/polyimide composite aerogel and its propertiesA novel polyimide composite aerogel was successfully synthesized by functionalizingclayhalloysitenanotubeswith3-aminopropyltriethoxysilane（APTES）as the inorganic reinforcing phase and homogeneously embedded in polyimide（PI）aerogel.The results showed that the interaction between the halloysite nanotubes with high aspect ratio and PI formed a three-dimensional network structure.The FHNTs/PI composite aerogel has low shrinkage（21.9%-30.79%）,low density（65.285-71.464 mg/cm³）,low thermal conductivity（39.18-42.57m W/（m·K））,high thermal stability（decomposition starts above 520℃）and excellent mechanical stability and excellent mechanical properties（maximum compressive strength of 80%compression is 1.14 MPa,2.65times that of pure PI aerogel;corresponding compressive modulus is 1.24MPa,2.75 times that of pure PI aerogel）.The functionalized APTES increases the interfacial compatibility between the clay inorganic phase and the polyimide precursor（polyamide acid,PAA）.（2）Preparation and performance study of halloysite/gelatin composite aerogelThe mechanical strength,pore size distribution,and thermal stability of gelatin-based aerogels were improved by the addition of HNTs.Chemical cross-linkersγ-glycidyl ether oxypropyltrimethoxysilane（GPTMS）and polyethyleneimine（PEI）were used to increase the interfacial interaction between HNTs and gelatin.Green,sustainable and low-cost composite aerogels were prepared by a"co-gel"system formed by the low-temperature physical gelation of gelatin and the chemical gelation of the chemical cross-linker,combined with the freeze-drying technique.The results show that the HNTs/GA composite aerogels have low density（31.98-57.48 mg/cm³）,high porosity（>95%）,low thermal conductivity（33.67-40.16 m W/（m·K））and superior plasticity.In addition,the mechanical strength of HNTs/GA composite aerogel with 80%compression and the maximum compressive modulus of 1.81 MPa and5.45 MPa,respectively,are 7.24 and 38.9 times higher than those of pure GA aerogel,and the corresponding specific modulus is 94.8 k N·m·kg^-1,which has good loading capacity.The hydrophobic HNTs/GA composite aerogel with a contact angle of more than 146°has a long time water resistance,which can further improve the practical application of biomass aerogel in humid environments.Thus,the biomass/clay composite aerogel will be a sustainable and renewable functional material with high mechanical strength and thermal insulation properties,which is expected to further promote the high-value utilization of biomass and clay.