Phase transfer agents facilitate the production of superinsulating silica aerogel powders by simultaneous hydrophobization and solvent- and ion-exchange

Zhao, Shanyu; Stojanović, Ana; Angelica, Emanuele; Emery, Olivier; Rentsch, Daniel; Pauer, Robin; Koebel, Matthias M.; Malfait, Wim J.

doi:10.1016/j.cej.2019.122421

Cited by 20 publications

(11 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, this strategy is very efficient in making larger aerogels that have better machinability. Some works, however, report silica aerogels without reinforcement (polymers or fibers) [69,71,72,76,78]. Regarding the processing, the majority of works compiled in Table 4 were prepared with TEOS as silica source (or as a co-precursor) [66,67,69,71,[73][74][75][76][77][78][79][80][81].…”

Section: Silica Aerogels: Effect Of Structural Properties On the Ther...mentioning

confidence: 99%

“…Regarding the processing, the majority of works compiled in Table 4 were prepared with TEOS as silica source (or as a co-precursor) [66,67,69,71,[73][74][75][76][77][78][79][80][81]. Ambient pressure drying (i.e., evaporation of the solvent at ambient pressure) is also becoming more common in superinsulating materials [66,69,[72][73][74]77]. This comes to show that silylation strategies (e.g., with hexamethyldisilizane or hexamethyldisiloxane) are efficient in producing materials with aerogel-like properties, as it was discussed earlier [82].…”

Section: Silica Aerogels: Effect Of Structural Properties On the Ther...mentioning

confidence: 99%

See 1 more Smart Citation

Thermal Conductivity of Nanoporous Materials: Where Is the Limit?

et al. 2022

View full text Add to dashboard Cite

Nowadays, our society is facing problems related to energy availability. Owing to the energy savings that insulators provide, the search for effective insulating materials is a focus of interest. Since the current insulators do not meet the increasingly strict requirements, developing materials with a greater insulating capacity is needed. Until now, several nanoporous materials have been considered as superinsulators achieving thermal conductivities below that of the air 26 mW/(m K), like nanocellular PMMS/TPU, silica aerogels, and polyurethane aerogels reaching 24.8, 10, and 12 mW/(m K), respectively. In the search for the minimum thermal conductivity, still undiscovered, the first step is understanding heat transfer in nanoporous materials. The main features leading to superinsulation are low density, nanopores, and solid interruptions hindering the phonon transfer. The second crucial condition is obtaining reliable thermal conductivity measurement techniques. This review summarizes these techniques, and data in the literature regarding the structure and thermal conductivity of two nanoporous materials, nanocellular polymers and aerogels. The key conclusion of this analysis specifies that only steady-state methods provide a reliable value for thermal conductivity of superinsulators. Finally, a theoretical discussion is performed providing a detailed background to further explore the lower limit of superinsulation to develop more efficient materials.

show abstract

Section: Silica Aerogels: Effect Of Structural Properties On the Ther...mentioning

confidence: 99%

Section: Silica Aerogels: Effect Of Structural Properties On the Ther...mentioning

confidence: 99%

Thermal Conductivity of Nanoporous Materials: Where Is the Limit?

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Then, theoretical models, including Thiele's formula, and the stress field were used to fit the test results, and the allowable slit length was finally estimated. In addition, some scholars [29][30][31] have discussed the fracture mechanism of composite materials with respect to the micro level. These studies investigated the fracture mode using fractured surface images obtained via scanning electron microscopy.…”

Section: Introductionmentioning

confidence: 99%

Study on tearing tests and the determination of fracture toughness of PVC-coated fabric

Bao

Zhang

2021

Journal of Industrial Textiles

View full text Add to dashboard Cite

In this study, detailed uniaxial in-plane tearing tests including uniaxial central, single-edge notched, and trapezoidal tearing tests of a type of polyvinylchloride (PVC)-coated polyester fiber fabric were conducted. Two types of tearing failure modes, brutal and progressive, were examined. In addition to differences in the descending sections of the stress–displacement curves and the membrane surface morphology near the crack, it was found that the uniaxial central tearing test could be replaced by the corresponding single-edge notched tearing test to minimize the usage of test materials. The configuration of the single-edge notched specimen, including the gauge length and width, was investigated to determine the conditions under which the tearing resistance of the practically nearly infinite membrane surface can be studied with finite-size specimens. To obtain the fracture toughness GIC, which characterizes the ability of materials to prevent crack growth, a theoretical method and two test methods were introduced. After comparing the methods, the test method based on the area of the parallelogram obtained from the zigzag wave in the descending section of the load–displacement curves was proved to be superior. The value of GIC obtained with this simple test method was relatively stable, and it could be used to evaluate the tearing resistance and calculate the tearing strength of the coated fabrics.

show abstract

“…To reduce the production cost of aerogels, the sodium silicate is considered as an inexpensive precursor to make aerogels. Recently, Zhao et al have reported aerogel powders synthesized from the least expensive precursor, sodium silicate without ion-exchange [7]. The most frequently used method for drying process is supercritical point drying because of the low surface tension of supercritical fluids, but it involves an expensive equipment [7] that can be dangerous and time consuming [8,9].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Zhao et al have reported aerogel powders synthesized from the least expensive precursor, sodium silicate without ion-exchange [7]. The most frequently used method for drying process is supercritical point drying because of the low surface tension of supercritical fluids, but it involves an expensive equipment [7] that can be dangerous and time consuming [8,9]. Another method is freeze drying [4], but it is hard to scale up because of the energy intensive requirements [10], and the method needs vacuum for solvent sublimation and low temperatures [11].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

View full text Add to dashboard Cite

Here 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.

show abstract

Phase transfer agents facilitate the production of superinsulating silica aerogel powders by simultaneous hydrophobization and solvent- and ion-exchange

Cited by 20 publications

References 52 publications

Thermal Conductivity of Nanoporous Materials: Where Is the Limit?

Thermal Conductivity of Nanoporous Materials: Where Is the Limit?

Study on tearing tests and the determination of fracture toughness of PVC-coated fabric

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

Contact Info

Product

Resources

About