The Design, Preparation And Properties Of Eva-based Thermal-insulating And Soundproof Materials

Laminated glass with sandwich structure such as glass/polymer interlayer/glass is a kind of safety glass that can prevent ordinary glass from hurting people by the fragment. As long as the development of energy saving in construction and denoising requirement, the investigation and application of heat-insulating and soundproof laminated glass receive particular attention. The modification of Ethylene vinyl acetate (EVA) interlayers on the heat-insulating and sound-insulating properties is significant to the functional laminated glass.According to the heat transfer mechanism of solid, additives with high porosity and low thermal conductivity can destroy the conductive chain in solid matrix, reduce the thermal conductivity, thus improving the insulating effect of the solid matrix. In the view of the principle of sound transmission, additive with high specific gravity can effectively increase the matrerials'surface density and damping as for the sound-insulating property, leading to the improvement in sound-insulating property of the interlayer. Based on this analysis, using EVA with high VA content as a matrix and Nano-SiO₂ having a rich resource and silica aerogel with the lowest thermal conductivity in reported solid materials as heat-insulating additives, EVA-based transparent heat-insulating composites were prepared; In the same way, the high specific gravity tetra-needle liked Zinc Oxide whisker (T-ZnOw), and two other kinds of different specific gravity minerals, SiO₂ and CaCO3, were used as soundproof additives to prepare the EVA-based soundproof interlayer.Series of EVA materials with different additives were prepared by extrusion blending method. The effect of additives contents on the visible light transmission, adhesive strength to the glass, and mechanical properties of the EVA materials were systematic studied. The heat-insulating properties and the effect factors of the SiO₂ contained EVA materials were investigated by both thermal constant analysis and an insulating box measurement. The results showed that EVA-based materials with larger additive contents or a constant content but larger specific surface areas possessed lower thermal conductivities. The thermal conductivities of EVA materials with 9.0 wt% Nano-SiO₂ and silica aerogel with specific surface areas being 300 m2/g and 800 m2/g got minimums of 0.2199 W/(m.k) and 0.1934 W/(m.k) that being 25.8% and 34.8% lower than the pure EVA, the balanced temperatures in the insulating box decreased 4.1℃and 4.2℃, respectively. In the compare of heat insulating effect of EVA materials modified by Nano-SiO₂ and silica aerogel, it came to a conclusion that 2.9 wt% of silica aerogel could provide the EVA material the same heat insulating effect as 7.3 wt% of Nano-SiO₂ did. Moreover, EVA/ silica aerogel material with 9.0 wt% of silica aerogel was still very transparent with a visible light transmission larger than 80%, while EVA/ Nano-SiO₂ materials could be transparent only when the Nano-SiO₂ content was lower than 5.6 wt%.Researches focused on the influence of fillers with different specific gravities on the sound transmission loss and loss factor were carried by the transmission loss tube for four-microphone transfer-function method and dynamic mechanical analysis. Furthermore, the effect of T-ZnOw contents on the sound-insulating performance was indirectly characterized by the damping properties. The results indicated that the sound transmission loss and loss factor both rose with the contents increased in the range of 3.8 wt% to 9.0 wt% or with fillers'specific surface areas at certain content. It turned out that the sound transmission loss and loss factor of EVA added by 9.0 wt% of T-ZnOw were the maximum, being 18.8 dB and 0.26086, respectively, which were 8.7% and 52.1% higher than the pure EVA.