Synthesis of silica aerogel particles and its application to thermal insulation paint
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pISSN: 0256-1115 eISSN: 1975-7220
INVITED REVIEW PAPER
INVITED REVIEW PAPER
Synthesis of silica aerogel particles and its application to thermal insulation paint Thi Hai Nguyen*, Ngoc Tam Mai*, Vasudeva Reddy Minnam Reddy**, Jae Hak Jung**,†, and Nguyen Tam Nguyen Truong**,† *South Vietnam Institute for Building Materials, lot I-3b-5, N6 Street, Tan Phu Ward, District 9, Ho Chi Minh City, Vietnam **School of Chemical Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan 38541, Korea (Received 12 February 2020 • Revised 5 May 2020 • Accepted 11 May 2020)
AbstractSilica aerogel (SA) particle was synthesized and characterized. The effects of silica content in silicic acid solution and molar ratio of trimethyl chlorosilane (TMCS)/pore water on silica aerogel physical characteristics such as surface area, pore volume, apparent density, and porosity were investigated. We observed that when the silica content increased from 4 to 7% of weight (wt%), the silica aerogel surface area increased from 628.5 m2/g to 914.4 m2/g and thereafter (>9%). When the molar ratio of TMCS/pore water increased from 0.1-0.4, the silica aerogel’s surface area increased from 816.8 m2/g to 924.1 m2/g. The highest silica aerogel surface area of 924.1 m2/g and porosity of 96.4% were achieved with a silica content in silicic acid of 7.011 wt% and TMCS/pore water of 0.4. Finally, silicon aerogel particles applied to water-based paint to improve the thermal insulation was about 1.2 oC with surrounding ambient temperature of 45 oC. Keywords: Aerogel, Silicic Acid, Sodium Silicate, Trimethyl Chlorosilane (TMCS), Surface Area
salt in gel. Actually, gels are defined as a substantially dilute crosslinked system, which exhibits no flow when in the steady-state; therefore, this is not really effective in removing sodium salt. On the other hand, ion exchange could solve the problems of sodium silicate which produces silicic acid with high purity of SiO2. In the solvent drying process, super critical drying (SCD) method is a high cost investment technology, limited capacity of instrument, requires high energy, and materials consumption for operation [1,5]. Therefore, ambient pressure drying (APD) technique was developed, which reduces the cost of silica aerogel significantly. Actually, hydrophilic silica aerogel is not as much consumed as the hydrophobic one, because of its wide application in water based and solvent based products. To obtain hydrophobic aerogel, silica gel needs to be modified to be hydrophobic before drying by SCD method. However, this hydrophobic characteristic could act as the agent that leads to reducing the surface tension between silica gel surface and solvent; thus solvents easily vaporize out of the pores of silica gel without collapse at ambient pressure. This APD method could produce silica aerogel particle with the equivalent quality with SCD method and is much cheaper. Therefore, APD method is suitable for producing silica aerogel particle which can be applied as thermal insulation in construction such as thermal insula
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