磷酸铁的研究进展

近年来,磷酸铁锂（LiFePO4）因具有突出优势已成为锂离子电池正极材料研究热点,磷酸铁与磷酸铁锂结构非常相似而成为正极材料的一种重要前躯体。介绍了磷酸铁的结构、制备方法研究现状和最新进展。     

响应面法优化羊毛脂甲酯化工艺研究

以羊毛脂为原料,采用甲醇钠、氢氧化钠2种催化剂,考察了反应温度、时间、催化剂用量、醇用量等因素对甲酯化的影响。结果表明:甲醇钠为催化剂时,在反应温度60℃、甲醇与羊毛脂质量比1.6、反应时间60 min、催化剂质量分数4%的条件下,酯转化率达到94.3%。用响应面法优化氢氧化钠为催化剂的羊毛脂甲酯化工艺,得到最佳工艺条件为:反应温度65.3℃、甲醇与羊毛脂质量比1.85、催化剂质量分数6%、反应时间90 min,在此条件下酯转化率可达94.2%。     

Controlled delivery of growth‐hormone‐releasing peptide 6 from the poly(lactic‐co‐glycolic acid)–poly(ethylene glycol)–poly(lactic‐co‐glycolic acid) copolymer and the effect of a growth‐hormone‐releasing peptide 6–copolymer hydrogel on the growth of rex rabbits

Growth‐hormone‐releasing peptide 6 (GHRP‐6) plays an important role in animal growth. However, there have been few studies focusing on the effect of GHRP‐6 on animal growth through controlled release systems. We synthesized the poly(lactic‐co‐glycolic acid) (PLGA)–poly(ethylene glycol) (PEG)–PLGA copolymer to investigate its controlled released effect on GHRP‐6 in vitro and to study the effect of a GHRP‐6–copolymer hydrogel on the growth of rex rabbits. The copolymer was synthesized with ring‐opening copolymerization and characterized by ¹H‐NMR. The interaction between GHRP‐6 and the copolymer was characterized by Fourier transform infrared spectroscopy and X‐ray diffraction. The body weight, serum level of insulin‐like growth factor 1 (IGF‐1), and hair coat quality were studied in rex rabbits. The results show that hydrogen bonds formed between the N? H group in GHRP‐6 and the C?O group in the copolymer. The release mechanism of GHRP‐6 was a combination of a diffusion‐controlled mechanism and an erosion‐controlled mechanism in the copolymer. The serum level of IGF‐1, hair coat quality, and body weight were all significantly higher in the GHRP‐6–copolymer hydrogel group than in the other groups. These results indicate that the copolymer effectively controlled the release of GHRP‐6. In addition, the GHRP‐6–copolymer hydrogel increased the synthesis of IGF‐1 for a prolonged period and, thereby, increased the rex rabbits' growth and hair coat quality. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40185.     

Enhanced performance by polyaniline/tailored carbon nanotubes composite as supercapacitor electrode material

Polyaniline/tailored carbon nanotubes composite (PANI/TCN) synthesized via situ polymerization of aniline monomer in the presence of tailored carbon nanotubes (TCN) is reported as electrode material for supercapacitors. The morphology, structure, and thermostability of the composite were characterized by scanning electron microscope, Fourier transform infrared, and thermogravimetric analysis. The electrochemical property of the resulting material was systematically studied using cyclic voltammetry and galvanostatic charge–discharge. The results show that the short rod‐like PANI dispersed well in the TCN with three‐dimensional network structure. The as‐prepared composite shows high specific capacitance and good cycling stability. A specific capacitance of 373.5 F g^?1 at a current density of 0.5 A g^?1 was achieved, which is much higher than that of pure PANI (324 F g^?1). Meanwhile, the composite retains 61.7% capacity after 1000 cycles at a scan rate of 50 mV s^?1. The enhanced specific capacitance and capacity retention indicates the potential of composite as a promising supercapacitor electrode material. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39971.     

Molecular weight control of poly(ethylene terephthalate) in extrusion process

A control strategy is developed to control molecular weight of recycled poly(ethylene terephthalate), PET, to overcome its degradation through an extrusion process. To obtain dynamic model of a twin screw extruder, steady‐state, and unsteady‐state experiments were performed. Discrete convolution models between inputs and outputs were obtained. Process inputs were considered as screw speed (SS), feed rate, and barrel temperatures and the output was viscosity average molecular weight (M_v) of the extrudate. SS and molecular weight of the product were chosen as the manipulated, controlled variable pair by considering singular value decomposition (SVD) technique. Model based PID controller and model predictive controller were used in the designed control scheme. By the simulation studies, both controllers were found to be successful for set‐point tracking, disturbance rejection cases; and were proven to be robust under modeling errors. POLYM. ENG. SCI., 54:459–465, 2014. © 2013 Society of Plastics Engineers     

Mechanical properties and microstructure changes of proton exchange membrane under immersed conditions

In this study, mechanical tensile stress–strain response and microstructure changes of proton exchange membranes (PEM) in immersed conditions are studied. The effects of water pretreatment and immersion time on stress–strain responses of Nafion^®?212 membranes are discussed. It is found that in the water immersion it took 24 h for the membrane to reach saturation equilibrium. Compared with dry membrane, immersed Nafion membrane shows a lower stress level at 30°C, but a higher stress level at 70°C. In situ small angle neutron scattering (SANS) experiments show that with the increase of temperature and water uptake, domains of the membrane become ordered and stay stable at around 60°C. Based on the observation, the relationship between the microstructure and mechanical properties is explained. POLYM. ENG. SCI. 54:2215–2221, 2014. © 2013 Society of Plastics Engineers     

可降解型低温精练助剂的制备及应用研究

采用脂肪醇聚氧乙烯醚、顺丁烯二酸酐和反丁烯二酸为主要原料合成了系列羧化对称型脂肪醇聚氧乙烯醚马来酸双酯Gemini表面活性剂,并将其作为棉织物的低温精练助剂。探讨了不同聚氧乙烯醚链段和不同脂肪链端基的双子表面活性剂用作精练剂的效果,结果表明羧化对称型月桂醇聚氧乙烯醚(9)马来酸双脂双子表面活性剂(DLEO9)的效果最好。详细研究了该双子表面活性剂对棉织物精练时温度、时间、碱和表面活性剂用量与失重和毛效之间的关系,精练后布样的失重率随精练温度的提高而增大,但毛细管效应随温度变化不同。最佳的精练工艺为:温度为85℃,时间为120 min,NaOH质量浓度为20 g/L,DLEO9质量浓度为1 g/L,浴比为1∶30。在相同条件下,DLEO9的精练效果优于常用的渗透剂JFC。     

Self-assembly synthesis of ZnO with adjustable morphologies and their photocatalytic performance

ZnO with hierarchical microspheres and hexagonal prisms structures were successfully synthesized by hydrothermal microemulsion route. Based on X-ray diffraction and scanning electron microscopy observation of the products at the different reaction time periods, the formation mechanism of three-dimensional hierarchical ZnO microspheres was proposed. Ultraviolet and visible diffuse reflectance spectra indicated that as-synthesized ZnO microspheres had enhanced absorption in both ultraviolet and visible light areas. The photocatalytic activities of as-synthesized products were evaluated by monitoring the degradation of methylene blue solution. Due to the synergistic effects of the high crystallization and special hierarchical structure, the hierarchical ZnO microsphere exhibited the highest photocatalytic activity.     

220t/h循环流化床锅炉温度测点布置及其仪表选型

结合某年产20万t乙二醇项目,分析220t/h高温高压低倍率循环流化床燃煤锅炉温度测点的布置。通过对比各种温度检测仪表的优、缺点,并分析温度测点处介质的特点,给出了安化220t/h循环流化床锅炉温度仪表的选型方案。     

一种基于可预测偏最小二乘法的故障检测方法

将可预测元分析(Fore CA)与偏最小二乘法(PLS)结合用于故障检测,在选取合适的可预测元的基础上,运用偏最小二乘回归,进一步提高模型对系统的预测能力,克服了偏最小二乘回归方法无法反映系统动态时序特性的缺陷,并构造CUSUM统计量和SPE统计量以检测故障是否发生。最后通过TE模型上的仿真实验结果表明:Fore PLS方法能有效检测慢漂移等故障。