Cellulose nanofibril reinforced silica aerogels: optimization of the preparation process evaluated by a response surface methodology

RSC Advances ◽  
2016 ◽  
Vol 6 (102) ◽  
pp. 100326-100333 ◽  
Author(s):  
Jingjing Fu ◽  
Chunxia He ◽  
Jingda Huang ◽  
Zhilin Chen ◽  
Siqun Wang
Keyword(s):  
Mechanical Properties ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Preparation Process ◽  
Cellulose Nanofibril ◽  
Drying Method ◽  
Composite Aerogels

CNF–silica composite aerogels with reinforced mechanical properties were prepared under an ambient pressure drying method and optimized by a response surface methodology.

Control of porous properties of ambient dried sodium silicate-based aerogels using response surface methodology

2019 ◽  
pp. 089270571987631
Author(s):  
Seyed Jalal Hosseini-Nasab ◽  
Mohammad Saber-Tehrani ◽  
Majid Haghgoo ◽  
Parviz Aberoomand-Azar
Keyword(s):  
Response Surface Methodology ◽  
Porous Structure ◽  
Response Surface ◽  
Pore Diameter ◽  
Ambient Pressure ◽  
Volume Ratio ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Simultaneous Increase ◽  
Independent Variables

In this work, response surface methodology (RSM) in combination with central composite design was employed to study the effect of independent variables on the nanoporous characteristics of silica aerogels prepared via ambient pressure drying. Different techniques such as attenuated total reflection–Fourier transform infrared, field-emission scanning electron microscopy, Brunauer–Emmett–Teller, and thermogravimetric differential thermal analyses were used to characterize the aerogel samples. The independent variables in this study were water:Na2SiO3 and trimethylchlorosilane (TMCS):Na2SiO3 volume ratio. The results showed that contemporaneous change of these factors affects the porous structure of silica aerogels considerably. Actually, when water:Na2SiO3 and TMCS:Na2SiO3 volume ratio were 6–7 and 0.8–1.4, respectively, specific surface area was maximum (∼660 m2 g−1). In addition, in this range, mean pore diameter was minimum, approximately 18 nm. Generally, the increasing water:Na2SiO3 volume ratio (to about 8), and the simultaneous increase of TMCS:Na2SiO3 volume ratio (to about 1.6), led to the decrease of mean pore diameter, while the density of the aerogels increased slightly. The combination of using low-cost precursors and ambient pressure drying method followed by applying RSM for producing silica aerogels with optimized properties is a key step toward commercializing these materials. Such a porous structure is ideal for thermal insulation applications.

The effect of pH on the physicochemical properties of silica aerogels prepared by an ambient pressure drying method

2007 ◽  
Vol 61 (14-15) ◽  
pp. 3130-3133 ◽  
Author(s):  
Seunghun Lee ◽  
Young Chul Cha ◽  
Hae Jin Hwang ◽  
Ji-Woong Moon ◽  
In Sub Han
Keyword(s):  
Physicochemical Properties ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Effect Of Ph

Solvents Effects on Physicochemical Properties of Nano-Porous Silica Aerogels Prepared by Ambient Pressure Drying Method

2006 ◽  
Vol 510-511 ◽  
pp. 910-913 ◽  
Author(s):  
Seung Hun Lee ◽  
Eun A Lee ◽  
Hae Jin Hwang ◽  
Ji Woong Moon ◽  
In Sub Han ◽  
...  
Keyword(s):  
Ph Value ◽  
Ambient Pressure ◽  
Average Pore Size ◽  
Porous Silica ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Average Pore

Hydrophobic silica aerogels were synthesized by an ambient pressure drying method from silicic acid with a different pH value, which was prepared from sodium silicate solution (water glass). In this study we chose various hydrocarbon class solvents such as pentane, hexane, heptane, and toluene, and performed surface modification in TMCS (trimethylchlorosilane)/solvent solutions in order to improve reproducibility in aerogel production. Densities of the aerogels were about 0.1 ~ 0.3 g/cm3 , and apparent porosities were 88 ~ 96 %, depending on the processing conditions. Specific surface area was approximately 730 ~ 950 m2/g, and average pore size around 10 nm.

scholarly journals Synthesis of sodium silicate-based silica aerogels with graphene oxide by ambient pressure drying

2021 ◽  
Author(s):  
Oznur Kaya Cakmak ◽  
Khalil T. Hassan ◽  
Jiabin Wang ◽  
Xiao Han ◽  
Lidija Šiller
Keyword(s):  
Graphene Oxide ◽  
Surface Area ◽  
Sodium Silicate ◽  
Ambient Pressure ◽  
Physical And Mechanical Properties ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Silica Matrix ◽  
X Ray Diffraction ◽  
Composite Aerogels

AbstractHere we study how graphene oxide affects silica aerogels and their physical and mechanical properties by examining volume shrinkage, pore volume, surface area and compressive strength of these composite aerogels. Composite aerogels were made through adding different amount of graphene oxide (GO) to sodium silicate precursor by using ambient pressure drying method. Additionally, the chemical composition of the composite aerogels was determined using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. A rougher structure was observed when the GO loading increased and the characteristic peak of GO in XRD disappeared due to the random distribution of GO within the silica matrix. FTIR spectrum of composite aerogels shows that the relative intensity of silanol groups on the silica matrix have downward tendency with the addition of GO. The specific surface area had maxima with the addition of 0.01 wt% GO surface area to 578 m2 /g. The mechanical strength of aerogels was increased, with the loading of GO from 0.0 wt% to 0.2 wt%, and the compressive modulus increased from 0.02 MPa to 0.22 MPa.

Synthesis of Silica Aerogel Thin Film from Waterglass

2007 ◽  
Vol 124-126 ◽  
pp. 671-674 ◽  
Author(s):  
Young Chul Cha ◽  
Chul Eui Kim ◽  
Seung Hun Lee ◽  
Hae Jin Hwang ◽  
Ji Woong Moon ◽  
...  
Keyword(s):  
Thin Film ◽  
Water Glass ◽  
Ph Value ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Dip Coating ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Silica Precursor ◽  
Dip Coating Technique

Hydrophobic thin film silica aerogels were synthesized by ambient pressure drying method from silicic acid which was prepared from sodium silicate (water glass) solution. The pH value of the silica precursor sol was adjusted to make a spinable sol, and gel films were coated on a glass substrate by dip coating technique. Aerogel-like thin films with the thickness of about 1 μm could be successfully fabricated by repeating the dip coating process three times.

scholarly journals Effect of sodium bicarbonate solution on methyltrimethoxysilane-derived silica aerogels dried at ambient pressure

2021 ◽  
Author(s):  
Yujing Liu ◽  
Xiao Han ◽  
Balati Kuerbanjiang ◽  
Vlado K. Lazarov ◽  
Lidija Šiller
Keyword(s):  
Contact Angle ◽  
Sodium Bicarbonate ◽  
Pore Diameter ◽  
Ambient Pressure ◽  
Sodium Bicarbonate Solution ◽  
Hydrophobic Surface ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Average Pore

AbstractHere we present an economical ambient pressure drying method of preparing monolithic silica aerogels from methyltrimethoxysilane precursor while using sodium bicarbonate solution as the exchanging solvent. We prepared silica aerogels with a density and a specific surface area of 0.053 g·cm−3 and 423 m2·g−1, respectively. The average pore diameter of silica aerogels is 23 nm as the pore specific volume is 1.11 cm3·g−1. Further, the contact angle between water droplet and the surface of silica aerogels in specific condition can be as high as 166°, which indicates a super-hydrophobic surface of aerogels.

Preparation and Properties of Hydrophobic Silica Aerogels by Ambient Pressure Drying Method

2011 ◽  
Vol 71-78 ◽  
pp. 1040-1043
Author(s):  
Hui Wang ◽  
Shi Ming Liu ◽  
Ling Ke Zeng
Keyword(s):  
Surface Area ◽  
Ambient Pressure ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Hydrophobic Properties ◽  
Large Pore Volume

Silica alcogels were prepared by hydrolysis with hydrochloric acid and condensation with NH4OH of ethanol diluted tetraethylorthosilicate (TEOS) precursor and trimethylchlorosilane and hexane as surface modifying agent. The physical properties such as density, appearance, hydrophobicity, surface area, pore size distribution and thermal stability were measured. It was found that the physical and hydrophobic properties of the silica aerogels depend on the TMCS/hexane (V) volume ratio. The density decreased with increase ofV, and the aerogels are more hydrophobic asV=3%. The aerogels were thermally stable up to a temperature of 350 °C, and the aerogel prepared has a high surface area and large pore volume.

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