Preparation And Properties Of Transparent Nanocomposite Thermal Insulation Film Based On PVB

The glass in the window material has a poor thermal insulation performance and a high heat transfer effect,accounting for more than 30%of the building heat consumption.Recent years more and more buildings use a large number of PVB laminated safety glass to meet requirements of aesthetic and safety.Therefore,it is urgent to reform the laminated safety glass.Hollow silica can reduce heat conduction of glass bacause low thermal conductivity,tungsten bronze material can reduce the heat radiation of sunlight into the room by absorption of near infrared rays.In addition,nano-ZnO has the ability to absorb ultraviolet rays,which can reduce the damage of indoor objects and human body by ultraviolet rays.In order not to affect the transparency of the glass,it is necessary to overcome the problem of nano-fabrication of these oxide materials and nano-scale dispersion in PVB.A uniform nano-ZnO monodispersion with alcohol phase and cyclohexane phase were prepared by precipitation method combined with surface modification technique.The nano-ZnO particles dispersed in cyclohexane were used as template to prepare hollow silica with small size by reverse microemulsion method.The nano-ZnO and hollow silica nanoparticles were blended with CsxWO3 and PVB resin to prepare PVB/CsxWO3/ZnO and PVB/CsxWO3/hollow silica nano-composite thermal insulation film materials.The effects of synthesis factor on nano-ZnO and small-sized hollow silica and the effects of blending conditions on the properties of nano-composite thermal insulation film were studied.Nano-ZnO monodispersion was prepared by precipitation method.The effects of synthesis factor on nano-ZnO were investigated and the suitable preparation conditions are as follows.The liquid medium is methanol,time of adding TEOS is 4 min,amount of modifier is 30 wt%,modified temperature 70℃,modified time 1 h.Nano-ZnO particles have an ellipsoidal shape with a particle size of 5-10 nm and are monodispersed in ethanol and cyclohexane.ZnO dispersion has high visible transmission and stability that can keep for 6 months without precipitation.The nano-ZnO particles dispersed in cyclohexane were used as template to prepare small-sized hollow silica nanoparticles by reverse microemulsion method.The silicon source type and pH were investigated and the suitable preparation conditions were as follows.TEOS as silicon source with a dosage of 20 μL,concentration of emulsifier is 0.2 g/mL the addition of ammonia is 60 μL and the reaction time is 12 h.The as-prepared hollow silica nanoparticles have a particle size of 20 nm and the shell thickness is 7 nm that can disperded in ethanol.The nano-ZnO and hollow silica nanoparticles were blended with CsxWO3 and PVB resin to prepare PVB/CsxWO3/ZnO and PVB/CsxWO3/hollow silica nano-composite thermal insulation film materials.The effects of process conditions such as CsxWO3 addition and film material thickness on its properties were studied.The prepared PVB/CsxWO3/ZnO nano-composite film can be shielded to 340 nm by ultraviolet light,the visible light transmittance is as high as 83.2%and the near-infrared light transmittance is only 2.8%at 1400 nm which showing excellent ultraviolet and near-infrared barrier performance.PVB/CsxWO3/hollow silica film has high transmittance and excellent near-infrared shielding properties,which can significantly reduce heat radiation.In addition,hollow silica can reduce the thermal conductivity of the composite membrane material,which reduced from 0.47 W·-1m·K-1 to 0.36 W·m-l·K-1 when the addition amount of hollow silica is 9 wt%.