Study On Preparation And Performance Of Attapulgite-based Aerogels

Clay aerogels have many distinctive properties,including a high specific surface area,low density and low thermal conductivity,as a thermal insulation material in the construction field,which have more advantages and application prospects.Using the resource-rich,low cost nature inorganic materials to prepare a new type of inorganic aerogel materials,which have simple synthesis methods,comprehensive performance,are the focus of current development.In this work,we fabricated ATP-based aerogels consisting of the rod-like ATP nano-crystals and different additives by simple freeze-drying method.Then a variety of analysis methods SEM,BET,XRD,compressive stress and strain,TGA were performed to measure and characterize the ATP-based aerogels.Combining with thermal conductivity,thermal imaging,limiting oxygen index?LOI?,vertical level combustion?VFT?and so on,the thermal insulation performance of ATP-based aerogels was studied.Meanwhile,the mechanical properties about the aerogels were studied in this experiments.Part I:The ATP-based aerogels?ATP/PVA-MAC?were fabricated by simple mechanical mixing and freeze-drying method consisting of the rod-like ATP nano-crystals as raw materials,medical absorbent cotton fibers as additives,polyvinyl alcohol?PVA?as adhesives,and melamine as flame retardants.The morphology,mechanical properties,thermal stability and thermal insulation of the ATP/PVA-MAC were characterised and investigated,which showed that the raw materials in ATP/PVA-MAC are fully compounded and the ATP/PVA-MAC presented a three-dimensional network structure.The weight loss was small at only 2.5%before 200 ^oC in the TGA test,indicating the samples have excellent thermal stability.As well as,the materials had excellent compressive strength???=10.19×10⁴ Pa?,thermal insulation(?=0.046 W m^-1 K^-1)and flame retardancy?LOI=53.5%?.Part II:The ATP-based aerogels?ATP/PVA-SS?were fabricated by simple mechanical mixing and freeze-drying method consisting of the rod-like ATP nano-crystals as raw materials,soluble starch as additives,PVA as adhesives and melamine as flame retardants.The morphology,mechanical properties,thermal stability,thermal insulation and flame retardancy of ATP/PVA-SS were researched by SEM,BET,compressive stress and strain,TGA,thermal imaging,LOI,VFT,respectively.The results showed that the maximum compressive strength of ATP/PVA-SS could reach 10.23×10⁴ Pa,which had good mechanical stability.And the samples had high temperature resistance and excellent thermal insulation(?=0.053 W m^-1 K^-1).The limit oxygen index value could reach 59.8%,indicating the flame retardancy of ATP/PVA-SS is excellent,which had great potential as a heat insulation and fireproof materials in the construction field.Part III:The ATP-based aerogels?ATP/HC-PVP/PVA-x,x=0³0%:ATP/HC-PVP/PVA-0%,ATP/HC-PVP/PVA-10%,ATP/HC-PVP/PVA-20%,ATP/HC-PVP/PVA-30%?were fabricated by simple mechanical mixing and freeze-drying method consisting of the rod-like ATP nano-crystals as raw materials,hydroxyethyl cellulose?HC?and polyvinylpyrrolidone?PVP?as additives,and PVA as adhesives and melamine as flame retardants.The morphology,thermal stability,mechanical properties,thermal insulation and flame retardancy of ATP aerogels were researched by means of SEM,XRD,TGA,compressive stress-strain,thermal imaging,LOI,VFT,etc.The results showed that with the increasing of the concentration of PVA,the morphology of the aerogels had undergone a transition from a lamellar,macroporous disordered structures to a three-dimensional network-like structure,honeycomb patterns and small holes.The values of??were gradually increased and the maximum value was 4.31×10⁶ Pa in the mechanical performance test and the thermal conductivity???decreased from 0.087 W m^-1 K^-1 to 0.063 W m^-1 K^-1 in the thermal insulation performance test,suggesting the mechanical stability and thermal insulation were enhanced.However,in the TGA test,the weight loss rate gradually increased and the maximum value was 45.6%and the combustion distance in the VFT process became longer and longer,indicating that the temperature resistance and flame retardancy of aerogels were weakened.