PI纤维增强SiO2气凝胶的常压制备及性能研究

Preparation and characterization of polyimide fibers reinforced silica aerogel by ambient pressure drying

以正硅酸乙酯(TEOS)为硅源,盐酸、氨水为酸碱催化剂,聚酰亚胺(PI)纤维为增强相,常压干燥制备PI纤维增强SiO2气凝胶,表征材料化学组成、疏水性、微观形貌、孔径分布、压缩性能、隔热性能及热稳定性,研究以短切纤维和纤维毡为增强相时复合SiO2气凝胶的力学性能。制备的PI纤维增强SiO2气凝胶综合性能优越,密度为0.18 g/cm3,比表面积高达1 085.7 m2/g,平均孔径为12.4 nm,疏水角为154.6°,常温下导热系数为0.036 5 W/(m·K),室温至500℃质量损失4.5%,50%形变时抗压强度为1 MPa,有效解决了气凝胶力学性能、疏水性差的问题。PI纤维增强SiO2气凝胶轻质、高比表面积、良好的疏水性及较好的热学、力学性能,使其在隔热领域具有广阔的应用前景。

PI fiber mats reinforced SiO2 aerogel was synthesized by ambient pressure drying using ethyltetrasilicate(TEOS)as the silicon source,hydrochloric acid and ammonia as the acid-base catalyst,polyimide(PI)fiber mat as the reinforcing phase. The chemical composition,hydrophobicity,microscopic morphology,pore size distribution,compression performance,thermal insulation performance and thermal stability of the composites were characterized. The mechanical properties of the composite SiO2 aerogel were studied when composite with the fiber mat and short fibers. The PI fiber mat composite SiO2 aerogel prepared possess excellent comprehensive performance,the composite aerogel density is 0.18 g/cm3,specific surface area up to 1 085.7 m2/g,average pore size is 12.4 nm,hydrophobic angle is 154.6°,and thermal conductivity is 0.036 5 W/(m·K),the mass loss is 4.5% at room temperature to 500 ℃,and the compressive strength is 1 MPa at 50% deformation. The PI fiber mat composite SiO2 aerogel prepared in this study can overcome the problems of poor mechanical properties and poor hydrophobicity of aerogels effectively,due to its low density,high specific surface area,good hydrophobicity,good thermal insulation and mechanical properties,and thereby has a broad prospect of application.