Comparative studies on thermal and toughness properties of polybenzoxazine composites with two functionalized graphene oxides

Abstract

Graphene oxide (GO) was functionalized by polyether amine (PEA) via two methods which were one-pot modification in acetone (GON) and two steps with the intermediate product of GOCO-Cl generated (GONS). There were more PEA successfully grafted onto GO for GONS than GON. The onset polymerization temperatures of the benzoxazine (Bz) composites decreased by the inclusion of 1?wt% of GO, GON or GONS. Thermal stability of the polybenzoxazine (PBz) composites was significantly improved indicated from the increase of weight loss temperature. T₁₀, T₂₀ and T₅₀ values of the composites with GONS were higher than that of the others. Toughness of PBzs may be enhanced by the incorporation of nanofillers, and GONS had stronger interfacial interaction with PBz matrix than GON.     

Functionalized graphene oxide nanosheets with unique three-inone properties for efficient and tunable antibacterial applications

Developing antibiotics-independent antibacterial agents is of great importance since antibiotic therapy faces great challenges from drug resistance.Graphene oxide(GO)is a promising agent due to its natural antibacterial mechanisms,such as sharp edgemediated cutting effect.However,the antibacterial activity of GO is limited by its negative charge and low photothermal effect.Herein,the amino-functionalized GO nanosheets(AGO)with unique three-in-one properties were synthesized.Three essential properties(positive charge,strong photothermal effect,and natural cutting effect)were integrated into AGO.The positive charge(30 mV)rendered AGO a strong interaction force with model pathogen Streptococcus mutans(330 nN).The natural cutting effect of 100 ng·mL^-1AGO caused 27%loss of bacterial viability after incubation for 30 min.Most importantly,upon the near-infrared irradiation for just 5 min,the three-in-one properties of AGO caused 98%viability loss.In conclusion,the short irradiation period and the tunable antibacterial activity confer the three-in-one AGO a great potential for clinical use.     

卡尔费休法测定液态氯乙烯中水含量的研究

采用卡尔费休法测定了液态氯乙烯单体中的水含量。试验确定了采样工具、样品的预处理方式及选用溶剂的最优方案,并进行了精密度与准确度的验证。结果表明卡尔费休法测定液态氯乙烯单体中的水含量准确、快速,可以用来准确、及时地指导生产。     

基于ＰＩＤ控制算法的直流微网容错控制方法研究

构建直流微网容错控制对象模型，调节直流微电网的输出回路参数；以输出功率、直流微网的 参考电压、弱电网下系统惯性响应特征等为约束参量，构建直流微网容错控制目标函数，在不同电网强度下 进行直流微网容错控制的参数自整定性调节，采用无功环比例积分控制方法进行直流微网容错寻优分析， 建立模糊 ＰＩＤ控制模型，采用变结构的模糊 ＰＩＤ控制方法进行直流微网容错控制过程中的自适应加权学习 和误差反馈调节，实现直流微网容错控制改进设计。仿真结果表明，采用该方法进行直流微网控制的容错 性能较好，输出稳定性较强，具有较好的直流微网输出增益。     

High molecular weight poly(butylene terephthalate-co-butylene 2,5-furan dicarboxylate) copolyesters: From synthesis to thermomechanical and barrier properties

Poly(butylene terephthalate-co-butylene 2,5-furandicarboxylate) copolyesters (PBTFs) were synthesized from 1,4-butanediol, dimethyl terephthalate (DMT), and 2,5-furandicarboxylic acid (FDCA) by a two-step polymerization method. Their chemical structures were confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and carbon nuclear magnetic resonance before thermal properties were explored with differential scanning calorimeter and thermogravimetric analyzer. Results showed that PBTFs changed from semi-crystalline to completely amorphous when the content of FDCA unit was increased to 45 mol% at first, and then became crystallographic again with the further increment of FDCA unit to 75 mol%. For their mechanical properties, the tensile modulus and strength showed the similar trend, decreasing firstly and then increasing later. Their barrier to carbon dioxide and oxygen became better with the increasing of furan content due to the rigidity and higher polarity of furan ring. The performance of PBTFs copolyesters was investigated clearly, and the relative content of FDCA and DMT can be adjusted to satisfy different performance requirements.     

煤化工酸水汽提装置运行存在问题及解决方法

本文简述了酸水汽提工艺的发展概况和技术进展,详细介绍了煤化工酸水汽提装置实际运行中存在的几类主要问题,并提出切实可行的解决措施,具有一定的借鉴意义。     

再生水水源水质问题及对策

以郑州市五龙口污水处理厂为例,论述了城市污水处理厂二级出水中活性微生物、藻类和NO_3~-对再生水生产设施造成的不利影响,同时提出了应对措施。对聚氯化铝和聚氯化铝铁除磷效果进行了试验,结果表明,聚氯化铝除磷效果优于聚氯化铝铁。     

Growth Defects in Langasite Crystals Observed with White Beam Synchrotron Radiation Topography

Langasite single crystal was grown by the Czochralski method and its perfection was assessed by white beam synchrotron radiation topography. It is found that the growth core and the growth striations are the primary growth defects and they show strong X-ray kinematical contrast in the topographs. Another typical defect in LGS crystal is dislocation. The formation mechanisms of these growth defects in LGS crystals were discussed.     

人工颅骨用复合材料中微量甲基丙烯酸甲酯的气相色谱法测定

采用氢气焰离子化检测器(FID),以正丁醇为外标物,PEG-20M为固定相,甲醇作为溶剂,气相色谱法测定复合材料人工颅骨中微量MMA的含量。其相对标准偏差<0.022,平均回收率(n=4)为98.0％～99.1％。此方法操作简便,用于实际样品分析可得到满意的结果。