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Effects of Irradiation on the Structure-activity Relationship of Konjac Glucomannan molecular chain Membrane

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Chinese Journal of Structural Chemistry 2012年第6期31卷 857-866页

作者：吴春华彭述辉温成荣王丽霞熊波刘雅楠范琳琳姚闽娜庞杰 College of Food Science Fujian Agriculture and Forestry University Department of Food Science Guangzhou City Polytechnic

To know the effects of irradiation on the konjac glucomannan （KGM） molecular chain membrane, KGM membrane solution was treated with the irradiation dose of 0-20 kGy in this study, and the structure and properties of KGM membrane were analyzed with Infrared spectrum, Raman spectrum, X-ray, SEM scanning and so on. The results revealed that the effects of different irradiation doses on the KGM molecular chain structure were different. Higher irradiation dose （20 kGy） resulted in partial damage against KGM membrane crystal structure, and there was no obvious change for the amorphous structure; with membrane property test, the tensile strength of KGM membrane gradually increased with the increase of irradiation dose and its elongation at break reduced, but these changes were not significant, WVP value reduced; with SEM, the membrane surface treated with irradiation was smoother even than the membrane without treatment. In addition, when increasing the irradiation dose, membrane surface became more even, and arrangement was more orderly and compact. KGM membrane nrooerties, and it is an ideal Irradiation modification could effectively improve the modification method.

关键词： KGM molecular chain irradiation modification membrane structure mechanicalproperty

Density functional theory study on the effect of molecular chain length on NO_(2)oxidation of PPS oligomers

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分子科学学报 2024年第3期40卷 267-274页

作者： WANG-PANG Ziqin DIAO Yongfa LI Zihang College of Environmental Science and Engineering Donghua UniversityShanghai 201620China

molecular chain models of polyphenylene sulfide(PPS)with polymerization degrees ranging from 2 to 10 were *** geometries of the models,representing various lengths of molecular chains,were optimized using density functional ***,the activation energies and electronic properties of the reactions were *** findings indicated that the geometrical parameters of the PPS molecular chain model,with a polymerization degree exceeding 6,closely resemble actual PPS ***,the fluctuation in Mulliken charge of S atoms did not exceed 0.6%,and the variation in Mayer bond order was more *** investigation revealed that the C-S bond and C-H bond are weaker links in the molecular chain,susceptible to disruption under harsh *** of the oxidation reaction between NO_(2)and PPS revealed the formation of a chemical bond between O atom in NO_(2)and S atom in PPS,emphasizing the influence of the electronic properties of PPS on the *** activation energy for polyphenylene sulfide oxidation,with a polymerization degree greater than 6,remained constant at approximately 143 kJ·mol^(-1).Employing a molecular model of polyphenylene sulfide with a polymerization degree of 7 enhances the precision and reduces the computational workload in studying the oxidation reaction mechanism of PPS subjected to NO_(2).Selecting the appropriate length of the PPS molecular chain is crucial for investigating damage caused by flue gas components in PPS filter media and advancing filter media development further.

关键词： density functional theory polyphenylene sulfide molecular chain nitrogen dioxide activation energy

Transverse relaxation characteristic and stress relaxation model considering molecular chains of HTPB coating based on pre-strained thermal aging

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Defence Technology（防务技术） 2021年第3期17卷 821-828页

作者： Yong-qiang Du Jian Zheng Gui-bo Yu Jian-zhuang Zhi Shijiazhuang Campus Army Engineering UniversityShijiazhuang050003China Intelligent Manufacturing Institute Hebei College of Industry and TechnologyShijiazhuang050003China

In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with pre-strain of 0%,3%,6%and 9%,*** low-field1 H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging *** stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain *** results showed that with the increase of aging time,the decay rate of transverse relaxation curve became faster,the transverse relaxation time decreased,the value of combined parameter q Mrl increased,the proportion of crosslinking chain decreased,while the proportion of dangling chain ***,the stress relaxation modulus increased,the crosslinking network structure of HTPB coating became denser and the degree of crosslinking *** the initial aging stage,the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain *** the increase of aging time,the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually *** correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950,which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.

关键词： HTPB Pre-strain aging Transverse relaxation characteristic molecular chain Stress relaxation model