Study On Preparation And Properties Of Granular Silica Aerogel/Polyisocyanurate Rigid Foam Composites

This research aimed at solving the mainly present problem of heat insulating material with low thermal stability and poor flame retardant performance, and the design combining the polyurethane foam with silica aerogel was raised. The polyurethane foam materials had the properties of low thermal conductivity, high compressive strength, low smoke production, while silica aerogel with low coefficient of thermal conductivity, excellent thermal insulation performance and high porosity was qualitative light. The composite rigid foam insulation materials would be the production which had superior thermal stability and good flame retardant performance. A new type composite material of PIR/silica aerogel was synthesized by one-step method, and the influence on the flame retardancy, thermal stability and mechanical properties of composite after the Si O2 aerogel doped was studied. The test results are as follows:The influence of three different forms for granular silica aerogel on the composite material was preliminary studied. The results are shown as follows: the wet silica aerogel could reduce the performance of the composite mat erial and the properties of PIR foam composite materials with dry granular silica aerogels was optimum. In addition, the performances of PIR foam composite in matrix b system are superior than in matrix a system, especially for thermal stability and flame retardant.In order to reduce the viscosity of the system and increase the amount of silica aerogel, we choose matrix b system to prepared PIR foam composite materials with polyethylene glycol 600 as the raw material preparation, which could make composites foam good dispersion performance in the matrix. The dosage of granular silica aerogel was not only achieved 8%, oxygen index of the matrix foam was 29.4 in the low viscosity system and could reach the top flame retardant value of the polyurethane in past report. The oxygen index of PIR foam composite materials increased from 29.4%(0 wt.% aerogel) to 34.6%(8 wt.% aerogel). The compressive strength of PIR foam composite materials increased by 136% and the specific strength increased by 92.2%. TG curves showed that the thermal stability of composite s significantly improved with the increase of silica aerogel dosages and the residual quality was increased by 20.4%. Thermal conductivity was reduced by 32.7%(0.0233 W/(m·K) at 8 wt.% aerogel) compared with polyisocyanurate(PIR) rigid foam(0.0346 W/(m·K)). It illustrated that PIR foam composite materials with the granular silica aerogel could improve the heat insulation effect.FT-IR showed that the inclusion of silica aerogel particles did not change the chemical structure of PIR and was only used as the composition of inorganic filler in the PIR matrix. As can be s een from SEM, PIR foam composite materials adding suitable amount of silica aerogel had a significant improvement with better pore structure and bubble arrange neat. Compared with the matrix foams, the bubble pore structure of the composite was smaller and its mechanical performance was better while the density of bubble hole increased.In order to further reduce the cost of the composites foam, we added a kind of waste residue polyols. Waste residue is a by-products left at the preparation of 1,4 butanediol, which is a kind of complex polymer polyols. Test results indicated that the properties were improved except the the mechanical properties when waste residue polyols join in the matrix alone. Yet, the addition of waste residue polymer polyols and granular silica aerogel in matrix b can significantly improve both the flame retardant and heat insulation properties of PIR foams. In other words, the compressive strength and specific strength increased by 25.4% and 22.0%, respectively. Thermal stability of the composite foam was increased by 61.8%, and the oxygen index was improved by 17.0%. The thermal conductivity was reduced by 27.5% and cells porosity decreased. Generally speaking, the performance of the composite foam with waste residue polyols and granular silica aerogel was significantly improved, and also the cost was reduced.