Study on the thermal insulation performance of the core–shell skeleton graphene oxide/carbon composite aerogel

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hongli Liu ◽  
Peng Wang ◽  
Wenjin Yuan ◽  
Hongyan Li

Abstract Phenolic resin (PR) was grafted onto the surface of graphene oxide (GO) through π–π conjugation and chemical bonding. After carbonization, organic compounds turned into carbon layers with a thickness of about 10 nm and coated on the surface of GO formed a core–shell structure. Besides, the adiabatic interface formed during organic carbonization can effectively connect the aerogels into a three-dimensional network. The optimum mass ratio of GO was determined to be 10 wt% in the preparation of the precursor aerogel. The adiabatic interfaces (carbon) between GO lamellae could effectively reduce the solid phase heat transfer in aerogels (thermal conductivity is 0.0457 W m−1 K−1). At the same time, the existence of GO also ensured better mechanical properties of GO/carbon composite aerogel (compressive strength is 2.43 MPa) compared with the pure carbon aerogel (1.52 MPa), demonstrating the excellent heat-shielding performance and mechanical property of GO/carbon aerogel.

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1883 ◽  
Author(s):  
Weibing Zhong ◽  
Haiqing Jiang ◽  
Liyan Yang ◽  
Ashish Yadav ◽  
Xincheng Ding ◽  
...  

Flexible wearable pressure sensors have received extensive attention in recent years because of the promising application potentials in health management, humanoid robots, and human machine interfaces. Among the many sensory performances, the high sensitivity is an essential requirement for the practical use of flexible sensors. Therefore, numerous research studies are devoted to improving the sensitivity of the flexible pressure sensors. The fiber assemblies are recognized as an ideal substrate for a highly sensitive piezoresistive sensor because its three-dimensional porous structure can be easily compressed and can provide high interconnection possibilities of the conductive component. Moreover, it is expected to achieve high sensitivity by raising the porosity of the fiber assemblies. In this paper, the three-dimensional reduced graphene oxide/polyolefin elastomer (RGO/POE) nanofiber composite aerogels were prepared by chemical reducing the graphene oxide (GO)/POE nanofiber composite aerogels, which were obtained by freeze drying the mixture of the GO aqueous solution and the POE nanofiber suspension. It was found that the volumetric shrinkage of thermoplastic POE nanofibers during the reduction process enhanced the compression mechanical strength of the composite aerogel, while decreasing its sensitivity. Therefore, the composite aerogels with varying POE nanofiber usage were prepared to balance the sensitivity and working pressure range. The results indicated that the composite aerogel with POE nanofiber/RGO proportion of 3:3 was the optimal sample, which exhibits high sensitivity (ca. 223 kPa−1) and working pressure ranging from 0 to 17.7 kPa. In addition, the composite aerogel showed strong stability when it is either compressed with different frequencies or reversibly compressed and released 5000 times.


Author(s):  
Anderson A. B. C. Júnior ◽  
Gustavo S. G. De Carvalho ◽  
Lippy F. Marques ◽  
Charlane C. Corrêa ◽  
Adilson D. Da Silva ◽  
...  

The title compound, C14H11NO4, exists in the solid phase in the zwitterionic form, 2-{[(4-carboxy-3-hydroxyphenyl)iminiumyl]methyl}phenolate, with the H atom from the phenol group on the 2-hydroxybenzylidene ring transferred to the imine N atom, resulting in a strong intramolecular N—H...O hydrogen bond between the iminium H atom and the phenolate O atom, forming a six-membered hydrogen-bonded ring. In addition, there is an intramolecular O—H...O hydrogen bond between the carboxylic acid group and the adjacent hydroxy group of the other ring, and an intermolecular C—H...O contact involving the phenol group and the C—H group adjacent to the imine bond, connecting the molecules into a two-dimensional network in the (10\overline{3}) plane. π–π stacking interactions result in a three-dimensional network. This study is important because it provides crystallographic evidence, supported by IR data, for the iminium zwitterionic form of Schiff bases.<!?tpb=12pt>


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