Study on structure-property relationship of polyimide blends

Summary Three pairs of polyimide/polyimide blends (50/50 wt%) with different molecular structures were prepared by two ways, i.e. mixing of the polyamic acid precursors with subsequent imidization, and direct solution mixing of the polyimides. The blends were studied with DMA technique. The results obtained show that all the blends prepared with these two different ways are miscible, as there existed only one glass transition temperature (Tg) for all the blends. It is suggested that the miscibility of these polyimide/polyimide blends is a result of the strong inter-molecular charge-transfer interaction between the chains of their components.     

5—烃基—2,3—二甲基吡嗪的合成

2,3-二基-5,6-二氢吡嗪与醛或酮在氢氧化钠的乙醇溶液中反应制得16种5-烃基-2,3-二甲基吡嗪。产率66%～90%。其中6种为新合成的化合物。产率17%～87.9%。     

高岭土在碳热还原氮化过程中的相变

系统研究了苏州高岭土碳热还原氮化合成SiAlON过程在不同温度下的相变。对试样的XRD、SEM以及EDXA分析结果表明 ,1 30 0℃之前 ,试样中没有氮化物生成 ,物相为莫来石、石英和方石英 ;1 30 0℃时 ,高岭土开始发生氮化反应 ,生成过渡型SiAlON和β SiAlON。此时 ,石英和方石英相基本消失 ;1 4 0 0℃时 ,过渡型SiAlON、β SiAlON和X SiAlON三相共存 ,β SiAlON有所增多并有少量刚玉相生成 ;从 1 4 50℃到 1 550℃ ,Z值为 3的β SiAlON成为惟一的氮化产物 ,与少量SiC和刚玉相并存。莫来石在 1 50 0℃时完全消失     

偶联剂对地砖用PVC填充材料相态结构和力学性能的影响

研究了钛酸酯类偶联剂和硅烷类偶联剂对钙矿、硅酸盐填充的PVC填允材料力学性能、相态结构、密度、热失重率及吸水伸长率和耐热阻燃性能的影响。结果表明,偶联剂可改善填充PVC的抗冲性能,降低其拉伸强度,扫描电镜分析表明,填料越细,分散越均匀,越易被PVC树脂所包覆,力学性能越好,研究得到了比重大、热失重率低、吸水伸长率小、阻燃耐烧灼性好的高填充PVC硬质塑料地板砖。     

动态硫化技术及其发展

结合动态硫化技术的发展史,重点评述了国外80年代该技术的发展及其特点,揭示了TPV性能及特征与制备条件的关系;简介我国开发研究TPV的概况,并提出了看法。     

国产耐火材料在欧洲3 300t/d生产线上的整体配套

Fushe-Kruje水泥厂项目位于距阿尔巴尼亚首都地拉那市28公里处，是由黎巴嫩SEAMENT集团投资兴建的．是迄今阿尔巴尼亚最大的外商投资项目，设计能力为3300t/d新型干法水泥熟料生产线，是全套生产线由我公司设计、制造成套、施工、安装、调试及试生产的总承包项目。     

VOID FRACTION PROFILES IN PLANE-POISEUILLE FLOW OF VISCOELASTIC FOAMS

This investigation focuses on slow, isothermal, two-phase flow of gas bubble suspensions in Separan solutions, prepared with the help of a sodium borohydride blowing agent at room temperature. The total residence time in these experiments is much smaller than characteristic times for growth or rise of bubbles. The variation of bubble volume fraction across a narrow gap between two planes, is recorded at two locations along the flow direction. This is done with a Cesium gamma-radiation source focused on a region of area.012 cm² in the flow plane, and a Sodium iodide detector across the channel yielding a resolution of.01 over the range of void fractions investigated from.02 to.08. This measurement allows us to identify conditions under which the two-phase flow may be described by a two fluid model with a uniform bubbly core and a bubble free wall layer. With this two phase flow structure, a relative viscosity equation for the suspension is used to compute an apparent viscosity. Such calculations indicate that the observed reduction in apparent viscosity for the two phase flow may be attributed to a bubbly core which is more shear thinning than the medium. The additional shear thinning factor for the suspension is related to the elasticity of the medium.     

Catalytic properties of aluminated sepiolite in ethanol conversion

The aluminated sepiolite, obtained by alkaline treatment with KAlO₂, as well as the silver-exchanged aluminated sepiolite were tested in ethanol conversion. The reactions were performed at 280°C and with 50 Torr of ethanol in He. After the alumination through KA1O₂, ethanol dehydrogenation and ethanol dehydration resulted from the Lewis acidity. The dispersion of silver led to a bifunctional catalytic system and the overall catalytic activity and the selectivity towards the acetaldehyde production increased. As a result of the Prins reaction, a significant yield in butadiene was observed.     

On the membrane phospholipids and their acyl group profiles of adrenal gland

The phospholipid composition and their acyl group profiles from subcellular fractions of guinea pig adrenal gland and the same fractions from the cortex and medulla of the bovine gland were compared. The phospholipids of guinea pig adrenal were enriched in diacyl-glycerophosphocholines (GPC) which comprised over 50% of the total phospholipids, but the proportions of ethanolamine and choline plasmalogens, sphingomyelin and diacyl-glycerophosphoserine (GPS) were lower in guinea pig adrenals as compared to the bovine adrenals. In the bovine adrenal, sphingomyelin and diacyl-GPS were enriched in the medulla, whereas diacyl-glycerophosphoinositol (GPI) were enriched in the cortex. Although lysolecithin was present (up to 4.5%) in the bovine adrenal, only trace amounts of this lipid were detected in the guinea pig adrenal. Characteristic acyl group profiles were found associated with each type of the phosphoglycerides in adrenal membranes. However, acyl group profiles of the phosphoglycerides were not greatly different either between the bovine and guinea pig adrenal or with respect to the type of subcellular membranes isolated. Diacyl-GPC were enriched in 16∶0 and 18∶1, but also contained considerable amounts of 18∶0, 18∶2 and 20∶4. Diacyl-GPE were enriched in 18∶0, 18∶1 and 20∶4, while diacyl-GPI, diacyl-GPS, as well as alkenylacyl-GPE, were enriched in 20∶4. The lysolecithin from bovine adrenal membranes contained mainly 16∶0, 18∶0 and 18∶1 with only trace amounts of the polyunsaturated fatty acids. Other polyunsaturated fatty acids, such as 22∶4 and 22∶6, are apparently not prominent in the phosphoglycerides from either the bovine or the guinea pig adrenal gland.