Influence of Hydrolysis Time on Properties of SiO 2 Aerogels Prepared by Ambient Pressure Drying
- PDF / 1,840,722 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 65 Downloads / 217 Views
RESEARCH ARTICLE-CHEMISTRY
Influence of Hydrolysis Time on Properties of SiO2 Aerogels Prepared by Ambient Pressure Drying Wei Luo1 · Xin Shu2
· Binbin Xu1 · ZhaoHui Liu1 · Zhongwen Ou1 · JingMing Liu3
Received: 28 May 2020 / Accepted: 26 August 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract With ethyl orthosilicate as precursor and trimethylchlorosilane as surface modifier, hydrophobic SiO2 aerogels are prepared through sol–gel process combined with ambient pressure drying process. The influence law of different hydrolysis times on microstructure and physicochemical properties of aerogels when the reaction precursor is in the sol phase is studied. The results show that the hydrolysis time increases from 6 to 36 h, and the prepared aerogels have nanoscale mesoporous structure and hydrophobic properties. With the increase in hydrolysis time, the porosity and specific surface area of the samples increase and then decrease, and the density decreases and then increases, all of which reach their peaks at 18 h. The properties of samples are optimal after being hydrolyzed for 18 h. The prosperity is 96%, specific area is 1539.7706 m2 /g, the density is 0.08921 g/cm3 , and the contact angle is 148.3°. Keywords Hydrolysis time · Surface modification · Ambient pressure drying · SiO2 aerogels
1 Introduction SiO2 aerogel is a lightweight porous nano-material with complex three-dimensional network structure. The unique nanometer network structure endows it with many excellent physical and chemical properties, especially its extremely low thermal conductivity (0.005–0.1 W/(m K) [1] that makes it a new type of thermal insulation material to be widely used in the thermal field. In addition, SiO2 aerogels have been used in some other fields, such as electrical field (Cherenkov detection test), optical field (optical waveguide material) and acoustics field (sound absorption and sound insulation material) [2, 3]. The traditional supercritical drying process to prepare SiO2 aerogels is not conducive to industrial production because of its high cost, long cycle, complex operation and risks. In contrast, ambient pressure drying process is becom-
B
Xin Shu [email protected]
1
Department of Military Infrastructure, Army Logistics University of PLA, Chongqing 401311, China
2
Military Continuing Education Center, Army Logistics University of PLA, Chongqing 401311, China
3
National Defense Engineering Research Institute, Academy of Military Sciences, Beijing 100089, China
ing popular and has been the research focus in recent years due to its simple production equipment, low cost, short cycle and high safety factor [4]. The properties of aerogels prepared by ambient pressure drying largely depend on the preparation conditions. The core is to prevent gel structure from collapsing during drying process and to promote “springback effect” of the structure after solvent evaporation [5]. Bhagat and Iswar studied the effects of co-precursor modification and aging treatment on the properties of aerogels prepared by
Data Loading...
