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Modification of biomass furan-based PEF copolyester with glycerol
Chengzhi Liu,Dongsheng Zhao,Maliang Zhang,Kunmei Su,Zhenhuan Li 한국고분자학회 2024 Macromolecular Research Vol.32 No.1
In order to solve the problem of low molecular weight in the synthesis of poly(ethylene 2,5-furandicarboxylate) (PEF) copolyester with titanium-based catalysts, this paper introduce an appropriate amount of glycerol (GC) into PEF to branch the straight chain polyester though the transesterification-melt polycondensation method, which solve the problem of low resin viscosity and low molecular weight. The structures of the copolymers were characterized by 1H-NMR and 13C-NMR, and the results showed that the modified PEF copolyesters and poly(ethylene-co-glycerol 2,5-furandicarboxylate) (PEGFs) were successfully prepared. The intrinsic viscosity ([η]) of PEGFs copolyesters was characterized by Ubbelohde viscosity, and the results showed that the copolyester [η] was increased from 0.25 dL/g to 0.755 dL/g. The thermal properties of copolyester were characterized by differential scanning calorimetry and thermo gravimetry, and it was found that the glass transition temperature of PEGFs copolyester increased from 67.8 °C to 89.5 °C, and the maximum pyrolysis rate temperature increased from 386.6 °C to 402.8 °C. We characterized the UV resistance of PEGFs copolyester, and the results showed that PEGFs copolyester could be well degraded under ultraviolet light.
Wide-Gap Repair of Mar-M247 Superalloy via Powder Metallurgy Route
Xiufang Gong,Yankang Yu,Tianjian Wang,Ye Liu,Lin Zhang,Zhenhuan Gao,Hou Ziyong,Xu Chen,Shuang He,Xuanhui Qu 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11
Wide-gap defects repair of Mar-M247 superalloy was investigated by utilizing powder metallurgy. New interlayer alloy withrelatively high content of B and Zr was designed based on the isothermal solidification principle. The interlayer alloy ischaracterized by relative low melting temperature (1100 °C), and the contact angle of interlayer on the Mar-M247 substrateis ~ 70º. Based on the thermodynamic calculation results, the mixture powders with 80 wt% substrate powder and 20 wt%interlayer alloy powder was used as a filler to repair the wide gap with width of 2 mm. After repaired at 1230 °C for 2 h, nearfullydense gap was obtained. MC-type carbides, MB2-type boride, M3B2-type boride and Ni5(Zr,Hf)-type intermetallic wereobserved in the liquid zone. After post-weld heat treatment, the block borides, chain carbides and eutectic are successfullyremoved, and the tensile strength of the bonding zone is close to that of the Mar-M247 superalloy.
Disruption of Stamp/Ttll5 Gene in Male Mice Causes Sperm Malformation and Infertility
Geun-Shik Lee,Yuanzheng He,Edward J. Dougherty,Maria Jimenez-Movilla,Matteo Avella,Sean erullon,David S. Sharlin,Chunhua Guo,Smita Auasthi,Zhenhuan Zhang,Stephen P. Armstrong,Edra C. London,Weiping Ch 한국동물생명공학회(구 한국동물번식학회) 2012 발생공학 국제심포지엄 및 학술대회 Vol.2012 No.1