Preparation and characterisation of glass fibre–fumed silica composite core material VIP

Novel fibre/powder (glass fibre (GF)–fumed silica (FS)) composite core materials with different fibre to powder ratios were prepared by wet papermaking process. The composite core materials and corresponding vacuum insulation panel (VIP) samples were characterised to obtain an insight into their microstructure, tensile strength, uniformity and thermal conductivity. The results show that the addition of fumed silica will alter the pore structure of the glass fibre core material, and reduce the average pore size, pore volume and porosity of the core material. Moreover, addition of fumed silica can increase the tensile strength of the core material to a certain extent, but it will diminish the uniformity. Further investigation conclusively shows that the addition of fumed silica has little effect on the thermal conductivity of VIP in low vacuum, but the thermal conductivity of VIP is significantly reduced with the increase of fumed silica content in high vacuum. Compared to glass fibre core VIP, the thermal conductivity of fiber/powder composite core VIP is more stable and the service life would be longer.