Preparation And Properties Of Refractory And Water Resistant Polymer/clay Aerogel Insulation Materials

Polymer/clay aerogel materials exhibits outstanding performaces,including good fire resistace,chemical resistance,low density,and low thermal conductivity,which has the potential to be used as insulation materials.However,the poor water resistance of the porous structure of polymer/clay aerogels limit its application in the field of thermal insulation.Enhancing the mechanical properties of clay aerogels(increasing polymer content)while maintaining the low ammability appears contradictory.Post-treatment of polymer/clay aerogel with water-proof coating,while adding flame retardants,is adopted to fabricate aerogel material with good mechanical properties,flame retardancy,thermal insulation properties and optimized water resistance.In this study,poly(vinyl alcohol),montmorillonite and pentaerythritol phosphate(PEPA)were used as raw materials to prepare poly(vinyl alcohol)/clay aerogel composites with enhanced flame retardancy via freeze drying method.The mechanical properties,flame retardancy,thermal properties and water resistance of the resultant materials were investigated with universal material testing machine,oxygen index,cone calorimeter and moisture absorption device.The results show that the flame retardancy of the aerogel material significantly improved,while the mechanical properties of aerogel materials slightly improved.The material possess good thermal insulation properties(coefficient of thermal conductivity in the range between 0.0294 W/(m·K)-0.0451 W/(m·K)).The most importance of adding flame retardants is,to increase polymer content thus increasing mechanical properties while maintaining good flame retardancy.Because the raw materials PVOH/clay aerogel are dissolvable or easily absorb water,the aerogels possess poor water resistance,which leads to significantly decreased themal insulation properties.Thus water-proof and fire resistant coating material was prepared by solution blending of polyacrylic emulsion and PEPA in this study.Then the polymer/clay aerogels were directly coated and cured with heating and irradiation.The components of coating,coating thickness,and curing process on the materials properties,including mechanical properties,flame retardancy,insulation performance and the water resistance were studied with universal material testing machine,oxygen index,cone calorimeter and moisture absorption device.Results show that the flame retardancy and mechanical properties of the coated material obviously increase with increasing PEPA content and the coating thickness.Coating effectively increased the water resistance,thus obviously increased the insulation properties for the decreased moisture in the aerogel materials.Curing with gamma irradiation of 60 kGy has better effect than with heating at 80 ℃ from the viewpoint of both mechanical properties and water resistance.