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419 results on '"Wang, Jinggang"'

115. Homogeneous cyanoethylation of cellulose with acrylonitrile in a CO2 switchable solvent.

Author

Mi, Shu, Yao, Zongze, Liu, Fei, Li, Yiguo, Wang, Jinggang, Na, Haining, and Zhu, Jin

Subjects
ACRYLONITRILE, SOLVENTS, CELLULOSE synthase, HYDROXYL group, CELLULOSE, ORGANIC solvents
Abstract

Development of an anhydrous homogeneous method for the cyanoethylation of cellulose is highly desirable. In this study, a series of cyanoethyl cellulose (CEC) composites were homogeneously prepared via the Michael addition of acrylonitrile (AN) to the activated hydroxyl group of cellulose in a novel CO2 switchable solvent. The cellulose was dissolved in this solvent generating a nucleophilic cellulose carbonate intermediate, which is able to react with AN directly via Michael addition and results in CEC with a tunable degree of substitution (DS) by varying reaction conditions, such as temperature, reaction time, and the feeding ratio of acrylonitrile. The obtained CEC samples have DS values ranging from 0.12 to 1.03. The solubility of the CEC samples varies with DS values. This organic and anhydrous CO2 switchable solvent system enables the preparation of CEC with high quality without side reactions induced by water and much easier down-stream treatment, which is superior to other homogeneous counterparts. This study suggests a new platform for the synthesis of novel cellulose derivatives by Michael addition in the CO2 switchable solvent system in the future. [ABSTRACT FROM AUTHOR]

Published
2022
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118. Self‐healing and biodegradable copolyesters synthesized from 2,5‐furandicarboxylic acid applied as human skin.

Author

Zhang, Xiaoqin, Wang, Jinggang, Dong, Yunxiao, Wang, Qianfeng, and Zhu, Jin

Subjects
DIETHYLENE glycol, MOLECULAR weights, GLYCOLIC acid, ETHANES, HUMAN beings, POLYCONDENSATION, FATTY acid methyl esters
Abstract

The new self‐healing and biodegradable copolyesters, poly(ethylene‐co‐diethylene glycol adipate‐co‐furanoate) (PEAF), were synthesized from 2,5‐furandicarboxylic acid, dimethyl adipate, diethylene glycol and ethylene glycol by transesterification and polycondensation. Their number average molecular weight (Mn) varied from 49,400 g/mol to 71,500 g/mol while the polydispersity index ranged from 1.47 to 1.97. The study showed that by adjusting the proportion of adipate segments from 25 mol% to 65 mol%, the tensile modulus was found to be ranging from 4.95 to 0.29 MPa at room temperature, which was close to or even lower than the modulus of human skin. The excellent biodegradability of PEAFs was certified by the weight loss of 34.5% to 80.9% during enzymatic degradation. Finally, self‐healing properties were also discovered in PEAFs and the fastest self‐healing rate observed was 23.1 μm/h for PEAF‐65 at 37 °C. Due to these outstanding properties, PEAFs absolutely possess the potential to be used as human soft tissues, electronic skin, human‐machine interface and so on. [ABSTRACT FROM AUTHOR]

Published
2022
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134. Completely amorphous high thermal resistant copolyesters from bio‐based 2,5‐furandicarboxylic acid.

Author

Shen, Ang, Wang, Jinggang, Ma, Shugang, Fei, Xuan, Zhang, Xiaoqin, Zhu, Jin, and Liu, Xiaoqing

Subjects
POLYESTERS, NUCLEAR magnetic resonance spectroscopy, MOLECULAR weights, SULFONES, GLASS transition temperature, POLYBUTENES, RENEWABLE natural resources, TRANSESTERIFICATION, CHEMICAL synthesis, THERMAL resistance, AMORPHOUS substances
Abstract

Polyesters from renewable resources with glass transition temperature (Tg) higher than 100°C are crucial in broadening their application range. In this work, a series of high molecular weight copolyesters, poly(butylene bis[4‐(2‐hydroxyethoxy) phenyl] sulfone 2,5‐furandicarboxylate) (PBSF), was synthesized from bis[4‐(2‐hydroxyethoxy) phenyl] sulfone (BHEPS), bio‐based 1,4‐butanediol (BDO), and 2,5‐furandicarboxylic acid (FDCA) via transesterification. Nuclear magnetic resonance spectroscopy (1H‐NMR and 13C‐NMR) was used to confirm their chemical structures, composition, and sequence distribution. Characterizations demonstrated that with the increasing content of BHEPS unit, Tg of synthesized polyesters was increased from 38.2°C for PBF to 122°C for PBSF‐95, in which the content of BHEPS unit was 95%. However, the weight average molecular weight (Mw) of PBSF was dramatically decreased after the addition of BHEPS, from 95,300 g/mol for PBF to only 9600 g/mol for PBSF‐95, which was too low for practical application. Taking molecular weight, Tg, and mechanical properties into account, PBSF‐65 was considered to be a promising polyester with Mw of 28,500 g/mol, Tg of 104.7°C, tensile strength of 82 MPa, and elongation‐at‐break of 98%. Besides, it was a completely amorphous polyester with a transmittance of 89.9% by cutoff at 700 nm. Summarily, PBSF‐65 showed great potential to be used as raw material for the manufacture of baby bottles, children's toys, kitchen appliances, and beverage packaging, especially in the case when high transparency and heat resistance are required. [ABSTRACT FROM AUTHOR]

Published
2021
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135. A Simplified and Optimized Chemical Mechanism for Combustion of n-Pentane at Atmospheric Pressure

Author

Jiawen Qi, Xiong Chuchao, Wang Jinggang, Zhiqun Meng, Luo Jinghui, and Hou Liquan

Subjects
Materials science, Laminar flame speed, 020209 energy, Thermodynamics, Bioengineering, 02 engineering and technology, lcsh:Chemical technology, Combustion, Residence time (fluid dynamics), lcsh:Chemistry, chemistry.chemical_compound, atmospheric pressure, 020401 chemical engineering, 0202 electrical engineering, electronic engineering, information engineering, Chemical Engineering (miscellaneous), lcsh:TP1-1185, 0204 chemical engineering, chemistry.chemical_classification, optimized mechanism, Atmospheric pressure, Process Chemistry and Technology, Atmospheric temperature range, Pentane, Hydrocarbon, lcsh:QD1-999, chemistry, Extinction (optical mineralogy), n-pentane, simplified mechanism, combustion
Abstract

In the present study, the detailed mechanism of n-pentane combustion, including 697 species and 3214 reactions, is first simplified to a mechanism with only 26 species and 134 reactions, which is suitable for the pressure of 1 atm, temperatures of 1000&ndash, 1600 K, and equivalent ratios of 0.5&ndash, 1.6. However, when the equivalence ratio is 1.0, in the temperature range of 1000&ndash, 1100 K, compared with the detailed mechanism, the maximum error of the ignition delay time predicted by the simplified mechanism exceeds 20%. Therefore, based on the method of temperature sensitivity analysis, the simplified mechanism is further utilized through reducing the A-factor of 2HO2 = H2O2 + O2 (&minus, 1) and 2HO2 = H2O2 + O2 (&minus, 2) by 10 times. By comparing with the detailed mechanism and predicting the ignition delay time, laminar flame speed, species profile, and extinction residence time, it is found that the optimized mechanism has good accuracy in the applicable range, and is fully capable of simulating the combustion process of light hydrocarbon gas.

Published
2020

144. Synthesis of a fire-retardant and high Tgbiobased polyester from 2,5-furandicarboxylic acid

Author

Fei, Xuan, Zhang, Xiaoqin, Liu, Jingkai, Wang, Jinggang, and Liu, Xiaoqing

Abstract

A biobased diol (BDBE) is synthesized from vanillin, guaiacol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to generate a series of fire-retardant polyesters (PECBFs) via melt polymerization with ethylene glycol (EG), 1,4-cyclohexanedimethanol (CHDM), and 2,5-furandicarboxylic acid (FDCA). The chemical structure, sequence distribution, and molecular weights of the obtained polyesters are confirmed by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The results show that BDBE units contribute positively to the high glass transition temperature (Tg) and fire retardancy, while the CHDM moiety provides flexibility and chain propagation activity. As the content of BDBE is increased from 0 to 25%, the Tgof PECBFs increases from 82 to 95 °C, and the limiting oxygen index (LOI) increases from 22.4 to 27.5%. In the UL-94 combustion test, when BDBE units are more than 15%, the samples almost self-extinguish immediately once the flame is moved away. Their mechanical properties are also investigated, and their tensile modulus is stabilized between 1.7 and 1.8 GPa, while the elongation at break ranges from 5 to 56%. Biobased polyesters demonstrating satisfactory properties are reported in this work.

Published
2022
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