Fractional composition of partly hydrolysed polyvinyl acetate and its compatibility with hydroxypropyl methylcellulose in aqueous solutions

Fractionation of partly hydrolysed polyvinyl acetate (PVA) was performed by warming of its aqueous solutions. The following properties of the obtained fractions were determined: viscosity, molecular weight and molecular weight distribution, surface tension, and absorbance in the IR range. The blockiness of the polymer molecules, characterized by their behaviour towards iodine-containing systems such as I₂,-H₃BO₃ and I₂,-KI, was estimated. Fractionation of the aqueous solutions of PVA by warming is based mainly on the different internal molecular structure of the separated products, i.e. on the length of the vinyl acetate blocks in the PVA molecules and, to a lesser extent, on the degree of hydrolysis and the degree of polymerization. The more blocklike are the PVA molecules, the less compatible are the polymers in the PVA-hydroxypropyl methylcellulose (HPMC)-water system. At phase separation in this sytem the PVA molecules which are not compatible with HPMC are, in the first place, those of the highest blockiness.     

分子结构对增塑聚氯乙烯性能的影响

研究了聚合度、分子量分布和支化结构对增塑聚氯乙烯加工流变性能和物理力学性能的影响。结果表明，增塑ＰＶＣ的加工流变性能随聚合度的增加而恶化；拓宽分子量分布和引入支化结构均有利于加工流变性能的提高；增塑ＰＶＣ的拉伸强度随聚合度的增加而提高，而压缩永久变形却随之减小；分子量分布对物理力学性能的影响不大；支化ＰＶＣ的拉伸强度略有下降。     

Simulation of toxic gases and vapours removal by activated carbon filters

The system ASC carbon filter/cyanogen chloride was studied by simulation. Three filter configurations and several models, taking into account Langmuir adsorption and second-order reaction between the adsorbed toxic vapour and the active metal on the surface, were developed.The effects of axial dispersion, number of reaction units, film mass transfer units and intraparticle mass transfer resistance on the breakthrough time were studied.Simulation results show that a complex model should be used in order to predict with reasonable accuracy the protection imparted by these filters.     

国内外改质沥青生产的现状及其发展

煤焦油沥青是炼铝及碳素工业的重要原料之一，它地质量如何直接影响到制品的技术经济指标。近年来，随着科学技术的发展，煤焦油沥青重整改质技术引起重视。目前已有许多国家已生产出改质沥青来满足制取电炉炼钢超高功率电极以及制品铝电解板的要求证同国内对此也开始进行研制工作。介绍了国内外改质沥青生产的现状及发展，并提出了参考建议。     

HPVC／PP共混改性研究：Ⅲ低分子量反应性化合物作相容剂

采用低分子量反应性化合物作相容剂，即化学交联体系来改善ＨＰＶＣ／ＰＰ共混物的相容性。考察了在不同共混比下，不同化学交联体系对共混物力学性能的影响，并观察了共混物的微观形态。结果表明，采用低分子量反应性化合物作相容剂，共混物的拉伸强度提高，但冲击强度无改善。分散相尺寸减小，相间粘接得到改善。并比较了３种增容方法的效果，发现ＣＰＥ是ＨＰＶＣ／ＰＰ共混物的最佳相容剂。     

SBS APP复合改性沥青的研究

采用SBS、APP复合改性渣油,可以得到性能优良的改性沥青材料。其最佳配料和共混工艺条件为:SBS/(SBS+APP)之比0.4、外掺量20%、转速1930rPm、共混时间1.0 hr,共混温度20℃。     

新型难燃输送带胶粘剂的研制

以改性氯丁橡胶为主料、多异氰酸酯为固化剂制成的新型难燃输送带胶粘剂,具有粘接强度高、耐热性好、干燥时间短、难燃等特点,在常温常压下粘接输送带接头,固化30min即可负荷运行。     

Investigation of the Interaction of Sodium Chloride and Two Amino Sulfonic Acids,HEPES and MOPSO,by EMF Measurements

Ionic interactions in the two systems NaCl-HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) and NaCl-MOPSO (3-(N-Morpholino)-2-hydroxypropanesulfonic acid) have been studied in terms of their mutual influence on the respective activity coefficients of each component. Activity coefficients for each component of the two systems and for corresponding buffers are calculated from emf measurements of solutions containing NaCl, the aminosulfonic acid, and its conjugate base in a NalSE/solution/AgCl-Ag cell at 5, 15, 25, and 37 °C.     

An improved enzymic method for the determination of native and modified starch

An improved method for the determination of starch by sequential hydrolysis with thermostable bacterial α-amylase and fungal amyloglucosidase is described. Glucose was determined colorimetrically by a glucose oxidase-peroxidase-chromogen system at pH 7. Native normal and waxy starches, and distarch phosphate, gave quantitative yields of glucose with a high degree of precision (coefficient of variation less than 1%). Acetylated distarch phosphate, high-amylose starch and retrograded amylose were initially treated with 1M NaOH for 30 min, then neutralised and analysed successfully as normal starch. Oxidised starch did not give a quantitative yield of glucose because of the presence of dicarboxylic groups in the polymer. For samples containing normal and waxy starch the analysis was carried out in about 4 h. The method was applied to a range of starch-containing foodstuffs and the results are reported.     

修正步冷温度曲线试验研究

按修正步冷温度曲线对经步冷脆化的 2 .2 5Cr 1Mo和在加氢反应器内运行 5a的 2 2 5Cr 1Mo试块进行了修正步冷试验 ,评定了材料的回火脆性。结果表明 ,按修正步冷曲线进行修正步冷试验能使已经脆化的材料进一步脆化 ,为加氢反应器材料损伤的研究提供了一条途径。