Abstract
Silica aerogels are lightweight, highly porous nanomaterial with extremely large internal surface area but fragile and brittleness. To enhance the applicability of aerogels, fiber reinforced silica aerogel insulation blocks are prepared by frothing method. Polyurethane emulsion acts as binder whereas polyethylene (PE) fiber and polyurethane (PU) fiber is used as reinforcing phase. The effect of polyethylene fiber and polyurethane fiber on the performance of composites were characterized by material's chemical microscopic morphology, compression performance, recovery performance, surface area, thermal conductivity and hydrophobicity. The research results show that the prepared PU fiber reinforced silica aerogel insulation block has excellent comprehensive performance. The water absorption rate of decreased from 19.35% (0 phr, PU fiber) to 6% (20 phr, PU fiber), and comprehensive rebound rate was increased by 97.83% at 20 phr PU fiber compared with pure insulation block (83.88%). Meanwhile, the dimensional stability of the composite aerogel block is above 96%. PU fiber reinforced silica aerogel insulation block has light weight, good hydrophobicity and good thermal and mechanical properties, so it has a wide range of application prospects in the field of insulation.
Highlights
Aerogel has porous structure formed by interconnecting three-dimensional nano network frameworks, so it has high porosity (80% ~ 99.8%)[1], ultra-high specific surface area (800 ~ 1000 m2/g)[2], super low thermal conductivity [0.001~0.043 W/(m·K)][3] and very low density (0.003~0.5 g/cm3)[4]
Zhang et al explored the use of aluminum silicate fiber and glass fiber as silica aerogel reinforcements, and found that the composite filled with fibers and silica aerogel increased in compression strength than the fiber mat alone after 30% compression deformation
Silica aerogel is compounded on the fiber mat to prepare a block with strong mechanical properties, or the aerogel is first made into powder, and placed between two plates to form a sandwich-like insulation block, the thermal insulation performance of this sandwich product is difficult to reach the ideal level of super thermal insulation materials
Summary
Aerogel has porous structure formed by interconnecting three-dimensional nano network frameworks, so it has high porosity (80% ~ 99.8%)[1], ultra-high specific surface area (800 ~ 1000 m2/g)[2], super low thermal conductivity [0.001~0.043 W/(m·K)][3] and very low density (0.003~0.5 g/cm3)[4]. It is necessary to strengthen the silica aerogel to prepare the silica aerogel thermal insulation composite material with strong mechanical properties[4].
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