材料期刊网，材料期刊，材料类期刊，材料期刊投稿

Synthesis of Polycaprolactone with Two Carboxyl End Groups

Qijin ZHANG , Wenying XU , and Zhiyong WANG (Dept. of Mater. Sci. & Eng. , University of Science and Technology of China , Hefei , 230026 , China)(To whom correspondence should be addressed)(Dept. of Modern Chemistry , University of Science and Technology of Ch

材料科学技术（英文）

At 225℃. caprolactone has been polymerized in the presence of succinic acid under dry nitrogen atmosphere. Characterizations of the polymer through IR and molecular weight measurements by 1H-NMR and end group titration have shown that the polycaprolactone obtained is of two carboxyl end groups. The molecular weight of it increases with decreasing of the acid content in the reaction mixture under the same polymerization conditions. With a certain ratio of acid to caprolactone. the maximum of molecular weight of the polymer will be reached at the reaction time of 3h.

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University of Science and Technology Beijing

JIA Shizhen University of Science and Technology Beijing , China.

材料科学技术（英文）

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Abstracts of papers from Journal of University of Science and Technology Beijing

稀有金属（英文版）

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Huazhong University of Science and Technology(H.U.S.T)

材料科学技术（英文）

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欢迎投稿、订阅《Journal of Wuhan University of Technology-Materials Science Edition》

武汉理工大学学报-材料科学版(英文版)

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CORRELATION BETWEEN STRESS COMPONENTS AND STRESS CORROSION CRACKS IN BRASS Lecturer,Department of Materials Physics,University of Science and Technology Beijing,Beijing 100083,China

QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.

关键词: stress corrosion cracking , null , null , null