Preparation And Performance Study Of Solar Thermal Composite Materials Imitating Polar Bear Fu

Traditional solar photo thermal materials are difficult to meet the large-scale use in buildings because of their high cost,easy damage,and large-scale manufacturing difficulty and safety risks.Inspired by the structure of polar bear fur,a low-cost,environmentally friendly and flame retardant solar photo thermal composite was prepared.The transparent and thermal insulation layer was prepared by warp knitted spacer fabric and epoxy resin,and the solar photo thermal composite based on textile was prepared by using black non-woven fabric as heat absorbing layer.Firstly,reflective materials are introduced to enhance the light transmittance of spacer fabric(i.e.light transmission and heat insulation layer).Then,the fluorescent material is loaded into the heat absorbing layer by polyvinyl alcohol(PVA)to improve the photo thermal conversion ability of the composite.A transparent intumescent flame retardant was synthesized,which gave textile solar thermal composites good flame retardant properties.The specific research contents are as follows:Firstly,the transparent insulation layer was prepared with warp knitted spacer fabric as support material and epoxy resin as packaging material;a solar thermal composite with polar bear fur structure was prepared by using black non-woven fabric as heat absorbing layer.The composite has good light transmittance and low thermal conductivity,which meets the standard of thermal insulation material,and also has compression and cushioning properties.Secondly,based on the above textile solar thermal composites,a spacer fabric with high light transmittance is constructed through a reflective coating with excellent reflective characteristics.It is found that when the reflective material is coated on the top layer of the spacer fabric and the light intensity is 1k W/m~2,the photothermal conversion temperature can reach up to 84.3℃.Then,based on the black non-woven fabric,the fluorescent photo thermal fabric is constructed by introducing the fluorescent material with excitation emission characteristics.The effects of fluorescence type,PVA concentration and fluorescence concentration on photo thermal conversion were studied.The results show that when the PVA concentration is 5%and the fluorescence concentration is 0.5%,the photo thermal conversion temperature of the composite prepared by the blue-green fluorescent material is as high as 99.4℃.Finally,a transparent intumescent flame retardant was synthesized in order to make the solar collector have fire-proof property,which can reduce the influence of light transmission to the composite material as far as possible.The light transmittance,thermal stability and combustion performance of the composite were studied by adjusting the proportion of each component of the flame retardant,and the transmittance flame retardant with LOI of 33.4%and vertical combustion grade V-0was obtained.The solar thermal composite materials with good flame retardant performance were prepared.