Block copolymers comprising poly(ethylene oxide) and poly(hydroxyethyl methacrylate) blocks: synthesis and characterization

Monofunctional poly(ethylene oxide) macroinitiators with a molecular weight of 2000, 5000, 10?000, 20?000 and bifunctional poly(ethylene oxide) macroinitiators with a molecular weight of 20?000 were used for the atom transfer radical polymerisation (ATRP) of hydroxyethyl methacrylate (HEMA) in ethylene glycol as a solvent. The polymerisation proceeds in a controlled way up to high conversions. The molecular weight of the obtained copolymers increases linearly with conversion. A high rate of polymerisation was observed for the ATRP of HEMA. The effect of the poly(ethylene oxide) moiety on the course of the reaction is limited to solvating effects. The surface analysis of poly(ethylene oxide)/poly(hydroxyethyl methacrylate) block copolymers by means of atomic force microscopy in tapping mode using phase imaging shows phase separated domains with characteristic features related to the volume fraction of the respective blocks.     

The influence of antioxidants on the oxidation stability of biodiesel

Oxidation stability of bodiesel is an important issue because FA derivatives are more sensitive to oxidative degradation than mineral fuel. Therefore, in the most recent European Specifications for biodiesel, a minimum value of 6 h for the induction period at 110°C, measured with a Rancimat instrument, is specified. To guarantee this value at the filling station, the use of additional antioxidants will be necessary. In this paper we show the influence of different synthetic and natural antioxidants on the oxidation stability, using the specified test method. Biodiesel produced from rapeseed oil, sunflower oil, used frying oil, and beef tallow, both undistilled and distilled, was investigated. The four synthetic antioxidants pyrogallol (PY), propylgallate (PG), TBHQ, and BHA produced the greatest enhancement of the induction period. These four compounds and the widely used BHT were selected for further studies at concentrations from 100 to 1000 mg/kg. The induction periods of methyl esters from rapeseed, oil, used frying oil, and tallow could be improved significantly with PY, PG, and TBHQ, whereas BHT was not very effective. A good correlation was found between the improvement of the oxidation stability and the FA composition.     

溶剂型复膜胶的改性研究

通过甲基丙烯酸甲酯接枝改性,提高SBS复膜胶的耐候性、耐老化性和粘接强度。讨论了单体、引发剂用量及反血温度、时间等对复膜胶性能的影响。     

Ni/PHAC催化甲醇羰基化合成乙酸工艺研究

以自制的酚醛树脂基活性炭(PHAC)负载镍为催化剂、碘甲烷为助催化剂,研究了在连续固定床反应器中催化甲醇碳基化合成乙酸的反应。探讨了反应温度、液体进料空时、甲醇与一氧化碳配比及加水量等反应工艺条件对甲醇羰基化反应及乙酸收率的影响,优化了反应的工艺条件。结果表明：反应工艺条件对甲醇羰基化反应及乙酸的收率影响较大,在系统压力为1．0MPa,反应温度558K,液体进料空时为10gcat．(mo1．h^-1)^-1,V(H20)：V(CH30H)＝3：100,n(CO)：n(CH30H)：n(CH3I)＝80：40：1的条件下乙酸收率最高达到了67．1％,而羰基化产物总收率可以达到79．1％,甲醇转化率可以达到93．8％,羰基化产物总收率和乙酸收率明显高于文献报道的同类催化剂。     

固载磷钨酸催化氯乙酸母液合成氯乙酸甲酯合成条件的优化

以氯乙酸母液和甲醇为基本原料,固载磷钨酸为催化剂,通过连续酯化的方法制备了氯乙酸甲酯;以氯乙酸甲酯的质量收率为基准,采用三因素三水平正交实验的方法对酯合成的条件进行了优化。实验结果表明氯乙酸母液与甲醇质量比对反应的影响最大,其次是母液与催化剂的质量比,而回流时间对反应的影响较小。正交实验得到的适宜反应条件为:母液与甲醇的质量比为10/7,母液与催化剂的质量比为10/1,回流时间为1.5h;在此条件下氯乙酸甲酯的质量收率为46.9%。     

Ammoximation of methyl ethyl ketone with H2O2 and ammonia over TS‐1

The ammoximation of methyl ethyl ketone and hydrogen peroxide to form methyl ethyl ketoxime was studied over zeolites (TS‐1) in the temperature range 308–373 K. The reaction was carried out in a batch autoclave at autogenous pressure. The conversion of methyl ethyl ketone and the selectivity to methyl ethyl ketoxime can reach 99% and approximately 100%, respectively, and the by‐products were the small amounts of corresponding methyl ethyl ketazine and trace amounts of unidentified compounds. Important factors were the reaction temperature, solvents and slow addition of hydrogen peroxide. The molar ratio of NH₃ to ketone had no significant effect on the conversion of methyl ethyl ketone, but increase in the ratio of NH₃ to ketone had a beneficial effect on selectivity. Copyright © 2006 Society of Chemical Industry     

气体中醋酸甲酯在活性炭上的动态吸附

研究了Calgon活性炭对醋酸甲酯的动态吸附行为,从穿透时间、穿透吸附量以及穿透曲线的形状等方面,考察了初始浓度、气速和温度等因素对活性炭吸附性能的影响。另外选择3种不同产地的国产活性炭在相接近的吸附条件下与Calgon活性炭进行对比,结果显示活性炭的微孔分布是与其吸附性能相关性较大的因素。     

Photocatalytic study of polymorphic titania synthesized by ambient condition sol process

Nanocrystalline titania of different phases were produced by ambient condition sol process with phase control originating from alterations in experimental variables. The produced titania photocatalysts were characterized by use of x-ray diffraction, BET surface area, transmission electron microscopy and related to methyl orange degradation. The results showed that the photocatalytic activity of brookite and anatase phase titania samples to be greater than that of Degussa P-25 and rutile phase titania sample. In addition, brookite, due to surface area considerations, appears to be the most photocatalytically active phase of titania.     

二卤代烷烃与甲酸甲酯的光促进羰基化反应

在光促进温和条件下,以甲酸甲酯为C1源,研究了非贵金属钴盐、铜盐催化二卤代烷烃（1,6-二溴己烷和1-氯-6-溴己烷）的羰基化反应。实验表明,1,6-二溴己烷和1-氯-6-溴己烷都是发生单羰基化反应,而且是C-Br键发生反应,分别得到的卤代羧酸甲酯为Br（CH2）6CO2CH3和Cl（CH2）6CO2CH3。     

Comparison of viscoelastic properties of polydimethylsiloxane/poly(2‐hydroxyethyl methacrylate) IPNs with their physical blends

Interpenetrating polymer networks (IPNs) of polydimethylsiloxane (PDMS) and poly(2‐hydroxyethyl methacrylate) (PHEMA) were prepared by sequential method. The dynamic mechanical parameters of obtained IPNs and their variations with the structural composition were evaluated. The results for the IPNs were compared with corresponding physically blended systems. The tensile properties and damping factor (tan δ) were assessed by stress–strain measurement and dynamic mechanical thermal analysis (DMTA), respectively. The glass–rubber transition temperature (T_g) was assessed by DMTA and differential scanning calorimetry (DSC). The results showed higher tensile strength and elongation at break for IPNs than those for physical blends. The shifts of T_g for that two components that make up the IPNs were greater than those for corresponding blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3480–3485, 2002