HP型合金乙烯裂解管运行1.4万小时破裂原因分析

在仅运行不到1.4万小时就开裂失效的乙烯裂解管上取样,进行组织、成份和性能的观察与测定.发现裂解管有不同程度的渗碳现象;渗碳造成材料的性能和组织的变化;有组织缺陷部位渗碳严重,甚至达到渗透状态等问题.经分析认为,乙烯裂解管的工作条件和组织缺陷的存在所导致局部不均匀的渗碳,是造成该裂解管开裂失效的主要原因.     

PET/LCP共混物的流变行为及其形态

就以不同刚性分子链热致液晶聚合物(LCP)为分散相的聚对苯二甲酸乙二酯(PET)共混物在加工温度范围内的流变性能,共混物熔体经过一系列流场发展起来的形态结构以及它们之间的关系进行了分析。研究表明,PET/LCP共混物为切力变稀的非牛顿流体,共混物熔体的粘度介于两种纯组分高聚物熔体之间,并且各组成的流动曲线于γ=600s～-1时相交;LCP熔体粘度对剪切速率的依赖性比PET熔体大;随着LCP含量增加,共混物的粘流活化能下降;LCP材料性质不同,对共混物流变性能将产生不同的影响。当分散相流体粘度大于基体高聚物的熔体粘度时,分散相很难变形;当分散相流体粘度小于基体时,则分散相的形态发展与加工条件有关。     

纤维用PET的燃烧及阻燃机理研究

通过对纤维用ＰＥＴ及添加不同阻燃剂的ＰＥＴ样品燃烧的气相、固相产物的红外光谱和ＣＯＮＥ实验分析,探讨了ＰＥＴ的燃烧和阻燃机理。认为ＰＥＴ燃烧时,在生成气相产物的同时,还会发生交联反应形成环烯结构。溴化磷酸酯阻燃剂具有磷、溴协同效应,可在气相到固相全过程内起阻燃作用;而芳香族溴化物主要是气相阻燃机理;聚合型溴化聚芳烃,由于聚合物链可能参与ＰＥＴ降解过程的交联反应,所以也是气相、固相均有阻燃作用。     

PET／HTH—6热致液晶有规嵌段共聚物的合成与表征

本文以端羟基的热致性液晶共聚酯HTH－6和端酰氯基的聚对苯二甲酸乙二醇酯（PET）齐聚物为原料，通过溶液缩聚法制备了含PET和HTH－6的嵌段共聚物，并用IR、POM、DSC、WAXD等手段对共聚物进行了表征，研究了热行为和结晶行为．DSC和POM结果证明这些嵌段共聚物都属向列型热致性液晶．在240～280℃无宏观相分离，而在较高温度（＞280℃）为两相结构．共聚物熔体冷却时出现PET晶相和HTH－6晶相的分离现象，随共聚物中HTH－6含量增加，PET的结晶速度明显增加，而共聚物中PET含量增加，HTH－6的结晶速度降低．     

PET／PMMA共混体系的结晶行为

对聚对苯二甲酸乙二酯（ＰＥＴ）在繁甲基丙烯酸甲酯（ＰＭＭＡ）存在下的结晶行为进行了比较详细的讨论。     

PC/PET/EPDM共混体系的形态结构

用WAXS和SAXS研究了PC/PET/EPDM共混体系的形态结构。结果表明,PC,EPDM导致PET的晶片厚度、非晶层厚度及长周期增加,但不影响晶胞尺寸及夹角。该共混体系为晶区与非晶区界面分明的两相体系。     

高分辨率微库仑法测定烯烃中微量水

采用JF - 3高分辨率库仑法微量水测定仪配合液态烃闪蒸气化取样进样器 ,分析丙烯、乙烯及 1 ,3—丁二烯中微量水含量 .测量范围为 3μg到 1 0 0mg微量水 ,仪器分辨率为 0 .1 μg ,检出限可达到 3μg/g ,精确度为 3μg≤样品水平≤ 1 0 μg时 ,3% ;1 0 μg≤样品水平≤ 1 0 0 μg时 ,2 % ;1 0 0 μg样品水平≤ 1 0 0 0 μg时 ,1 % ;1 0 0 0 μg≤样品水平时 ,0 .5 % .平均相对标准偏差为 1 .32 % ,回收率为 1 1 8% .操作简便 ,分析速度快 ,结果准确 .     

Synthesis and Characterization of EO／PO Random Copolyethers

Ethylene oxide (EO) and propylene oxide (PO) random copolyethers were synthesized by the sequential addition of the mixture of ethylene oxide and propylene oxide to propylene glycol (initiator) in the presence of potassium hydroxide(KOH), and characterized with infrared spectrum (FTIR) and nuclear magnetism resonance (NMR). The effects of catalyst concentration, reaction temperature, charging rate and EO/PO mixture ratio on the polymerization reaction were investigated. It was revealed that the optimal reaction condition is the ratio of 2.5 : 1 000(KOH mass vs. product mass), at 114.6℃ and pressure below 0.4 MPa. The residual KOH was neutralized by phosphoric acid (H3PO4 ). Then the crude copolyether was refined with adsorbents, and the refined copolyether, which contains less than 0.7 μg/ml K^ , was obtained as colorless, viscous liquid.     

稀土固体超强酸SO42-/TiO2-Ce(IV)催化合成环己酮乙二醇缩酮

制备了固体超强酸催化剂SO42-/TiO2-Ce(IV),并利用该催化剂催化合成了环己酮乙二醇缩酮,探讨SO42-/TiO2-Ce(IV)对缩酮反应的催化活性,较系统地研究了酮醇物质的量比、催化剂用量、反应时间诸因素对产品收率的影响.实验表明:SO42-/TiO2-Ce(IV)是合成环己酮乙二醇缩酮的良好催化剂,在n(酮)∶n(醇)=1∶1 5,催化剂用量为反应物料总质量的0.5%,环己烷为带水剂,反应时间1.0h的优化条件下,环己酮乙二醇缩酮的收率可达85.7%.     

Bacterial phytotoxins: Mechanisms of action

Many species of phytopathogenic procaryotes produce toxins that appear to function in disease development. The affect the plant in different ways, the end result of which is the elicitation of chlorosis, necrosis, watersoaking, growth abnormalities or wilting. The most extensively studied toxins cause chlorosis. They specifically inhibit diverse enzymes, all critical to the plant cell. This inhibition results in a complex series of metabolic dysfunctions ultimately resulting in symptom expression. Substances causing growth abnormalities consist of known phytohormones and other compounds with plant hormone-like activities, but which have no structural relationship to the known hormones. The former act in the usual manner but, because of their elevated levels and imbalances, the host's regulatory mechanisms are overwhelmed and abnormal growth results (hyperplasia, shoot or root formation); the mechanisms of action of the latter group are unknown. High molecular weight, carbohydrate-containing substances, also acting in unknown ways, cause tissue watersoaking or wilting. Likewise, we know little about toxins causing necrosis except for syringomycin which affects ion transport across the plasmalemma.