改性水泥专用丁苯胶乳的稳定性研究

以十二烷基苯磺酸钠为乳化剂,用过硫酸钾引发体系,制备了改性水泥专用丁苯胶乳,考察了乳化剂浓度、进料方式和搅拌形式对胶乳稳定性的影响.     

Thermogravimetric analysis of methyl methacrylate‐graft‐natural rubber

The thermal degradations of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) in nitrogen were studied by thermogravimetric analysis. The results indicate that the thermal degradation of MG in nitrogen is a one‐step reaction. The degradation temperatures increase along with the increment of heating rates. The temperature of initial degradation (T₀) is 0.448B + 362.4°C, the temperature at maximum degradation rate, that is, the peak temperature on a differential thermogravimetric curve (T_p) is 0.545B + 380.7°C, and the temperature of final degradation (T_f) is 0.476B + 409.4°C. The degradation rate at T_p is not affected by B, and its average value is 48.9%; the degradation rate at T_f is not affected by B either, and its average value is 99.3%. The reaction order (n) is 2.1 and is not affected by B. The reaction activation energy (E) and the frequency factor (A) increase along with B, and the apparent reaction activation energy (E₀) is 254.6 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2952–2955, 2002     

磷改性ZSM-5分子筛物化性质和裂解制乙烯性能的研究

The physicochemical features of phosphorus-modified ZSM-5 zeolites (SiO2/Al2O3 molar ratio is 25) were characterized by XRD(X-ray diffraction), BET(Brunauer, Emmett and Teller spcific surface area measurement), NH3-TPD(ammonia temperature-programmed desorption) and MASNMR(magic angle spinning nuclear magnetic resonance), and the performance on catalytic pyrolysis to produce ethylene was investigated with a light hydrocarbon fixed bed micro-reactor with n-octane as feed. The results show that the acid site density, acid intensity and hydrothermal stability of ZSM-5 zeolite were improved by phosphorus modification. When P205 content in ZSM-5 zeolite is higher than 2.5%, phosphorus modification can prevent ZSM-5 zeolite crystal structure transformation from orthorhombic to monoclinic. In addition, the dealumination of ZSM-5 zeolite framework was moderated by phosphorus modification under high temperature hydrothermal treatment. The results of n-octane pyrolysis on phosphorus-modified ZSM-5 zeolites show that ethylene yields of zeolites with different phosphorus content are almost the same under the same n-octane conversion. However, the modified zeolites with higher pyrolysis activity give lower yield of propene, butene and total olefin than lower pyrolysis activity under the same n-octane conversion.     

辣椒红色素的提取工艺及稳定性研究

红辣椒中含有纯天然辣椒红色素，研究了辣椒红色素的几种提取方法。用有机溶剂从辣椒中提取红色素，同时对不同温度、不同时间下的色素提取率进行测试，以确定最佳提取条件；研究发现，乙酸乙酯法可以有效地去除辣椒中的辣味，使产品应用于更广泛的领域。本文还研究了辣椒红色素对pH值、光照、温度、金属离子的稳定性。     

Application of hindered piperidine amine and/or tertiary amine in the modification of polyamide 6

PA 6 resin was produced in a hydrolytic‐polymeric process in which ε‐caprolactam was polymerized in the presence of water as initiator, isophthalic acid and benzoic acid as chain regulators, by polymerizing caprolactam in the presence of 7.5% by weight of water, 0.2% by weight of isophthalic acid, 0.1% by weight of benzoic acid, each percentage being based on caprolactam. By adding hindered piperidine amine and/or tertiary amine to the polymeric system, the effects of additives on the polymer were studied. The results showed that: the addition of 0.1 ～ 0.2% additives can improve the melt stability of polyamide 6; the addition of 0.2% additives can protect mechanical properties of polyamide 6 fibers after exposure to high temperature; and the addition of 0.05 ～ 0.25% additives can increase the amino end group content of polyamide 6 and thereby increase the dyeability of polyamide fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2489–2493, 2004     

SEBS/PP共混材料的研究及其进展

SEBS是一种用途广泛的新型弹性体材料,在常温下具有高弹性,高温下可直接加工成型。由于SEBS具有优异的耐臭氧、耐氧化、耐紫外线和耐候性能等,因此,应用范围广于普通SBS材料。但是,SEBS耐溶剂性和耐油性较差,常通过与其他材料共混改性来增强其加工性能。文章重点概述了苯乙烯-乙烯-丁烯-苯乙烯(SEBS)与聚丙烯(PP)共混材料的微观结构、相容性以及结构与性能的研究进展,介绍了近年国内外SEBS/PP共混改性的研究成果,包括填充油、无机材料、PPO、PC和PA6等改性体系,并比较了这些改性技术对SEBS/PP共混体系微观结构及性能的影响,近年内,SEBS/PP共混材料的理论研究和工程应用会有长足发展。     

天然橡胶不同硫化体系磨耗微观结构的研究

通过对天然橡胶不同硫化体系硫化胶磨耗前后的红外光谱分析，得知常温下硫化胶的磨耗历程是具有氧化反应的力化学反应，单，双硫键较多的硫化胶具有较好的耐磨性。     

专用丁苯胶乳对混凝土的改性

用自制的专用丁苯胶乳对混凝土进行改性,考察了聚合物与混凝土质量比(简称聚灰比)、水与混凝土质量比(简称水灰比)、消泡剂用量、养护条件和胶乳稳定性对改性混凝土性能的影响。结果表明,当聚灰比为12%、水灰比为35%、消泡剂质量分数为丁苯胶乳的3%时,且在混凝土浇铸后干养28d的条件下,改性混凝土的抗压强度、抗折强度、黏结强度及抗渗性比未改性混凝土分别提高了6%,9%,85%,50%。稳定性越好的胶乳对改性混凝土的性能提高幅度越大。     

Thermal analysis of montmorillonites modified with quaternary phosphonium and ammonium surfactants

The thermal stability of seven organically modified montmorillonites (‘organoclays’) has been investigated using differential thermal analysis, differential scanning calorimetry, and thermogravimetry in conjunction with X-ray diffractometry. Six organoclays were synthesised by replacing the interlayer inorganic cations, initially present, with quaternary phosphonium and ammonium surfactant cations. The samples modified with tetrabutylphosphonium (TBP), and butyltriphenylphosphonium (BTPP) ions have an appreciably higher thermal stability than the octadecyltrimethylammonium (ODTMA)-modified clays. Thus, in the case of TBP- and BTPP-modified montmorillonites, the onset temperature of decomposition is close to 300 °C. Samples modified with hexadecyltributylphosphonium (HDTBP) ions have a lower onset temperature of decomposition of 225 °C. In comparison, the onset temperature for ODTMA-montmorillonites (obtained at different concentrations of ODTMA-bromide) ranges from 158 to 222 °C, being highest where the concentration of intercalated surfactant is lowest. The onset temperature for a commercial alkylsilane-treated quaternary ammonium-modified organoclay (S-BEN N-400FP) is 207 °C. The basal spacing of the TBP- and BTPP-modified clays is 1.7–1.8 nm, indicating a monolayer arrangement of quaternary phosphonium ions in the interlayer space, while the value of 2.5 nm for HDTBP-montmorillonite indicates a more open structure. The ODTMA-modified samples have basal spacings ranging from 1.9 to 2.1 nm, indicative of a bilayer to pseudo-trilayer arrangement. The exceptionally high basal spacing of 3.4 nm for the S-BEN N-400FP organoclay might be due to interlayer penetration of organosilane hydrolysis products during synthesis. The thermal properties of organoclays are apparently related to the nature of the surfactants and their arrangement in the interlayer space of montmorillonite.     

电化学除盐对混凝土微观结构的影响

设计了一套钢筋混凝土的电化学除盐循环装置,研究了用0.001 mol/L Li2B4O7 氢氧化钙饱和溶液、氢氧化钙溶液以及蒸馏水作电解液的除盐效率,并用SEM和EDS等方法进行微观结构分析,结果表明:用0.001 mol/L Li2B4O7 氢氧化钙饱和溶液作电解液最有利于混凝土中Cl-的排除,并且经电化学除盐处理后混凝土水化产物中C-S-H凝胶分解,Ca(OH)2增多,并在孔壁形成沉淀,堵塞毛细孔,使表层混凝土孔隙率降低,而钢筋与混凝土界面Ca/Si增大。