Liquid viscosities and densities of HFC-134a+glycol mixtures

Liquid viscosity and density of six binary mixtures of HFC-134a with glycols [ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (400), and polypropylene glycol (2000)] have been measured in the temperature range from 273 to 333 K. The viscosity was measured by a rolling-ball viscometer calibrated with standard liquids of viscosities and densities (JS5, JS10, JS20, and JS50). The density was measured with a glass pycnometer. The uncertainties of the measurements were estimated to be less than 3.4 % for viscosity and 0.04 % for density, respectively. An equation is given to represent the obtained viscosity values as a function of weight fraction and temperature.     

聚丙烯催化剂的研发进展

综述了用于丙烯聚合的Ziegler-Natta催化剂在给电子体技术及催化剂制备工艺等方面,茂金属催化剂在制备丙烯均聚物、丙烯共聚物及特殊聚丙烯等方面,非茂单活性中心催化剂在丙烯活性聚合、丙烯与极性单体共聚及水介质聚合等方面的研发进展;讨论了聚丙烯催化剂的前景。     

助催化剂对TiCl_4/MgCl_2催化丙烯高温聚合的影响

研究了助催化剂种类(三甲基铝、三异丁基铝、三正己基铝、三乙基铝和甲基铝氧烷)及其含量对无内、外给电子体的TiCl4/MgCl2催化剂催化丙烯高温(100℃)聚合性能的影响,并用结晶分级分析、示差扫描量热和凝胶渗透色谱等方法分析了所得聚丙烯的结晶熔融行为和微观结构。实验结果表明,聚合温度从70℃升至100℃时,TiCl4/MgCl2催化剂的定向能力基本不变;100℃聚合时,以烷基化能力较弱的三异丁基铝为助催化剂时TiCl4/MgCl2催化剂的活性最高,而采用烷基化能力最强的三甲基铝为助催化剂时TiCl4/MgCl2催化剂的活性最低;100℃聚合时,助催化剂的种类对TiCl4/MgCl2催化剂的定向能力影响很小。     

纤维体积分数对K3D/MCPA复合材料力学性能的影响

本文研究了纤维体积分数对三维编织芳纶纤维增强铸性尼龙(简称K3D／MCPA)复合材料力学性能的影响。研究表明，K3D／MCPA复合材料有优异的抗冲击性能，冲击强度比三维编织芳纶纤维增强铸性尼龙(简称C3D／MCPA)和纯基体均有大幅度的提高，且随着纤维体积的提高而升高。K3D／MCPA复合材料剪切强度随纤维体积比的增大而增大，其纵向剪切强度低于纯基体和C3D／MCPA复合材料，但其横向剪切强度高于它们。K3D／MCPA复合材料弯曲强度与弯曲模量随纤维体积比的提高而提高，但与相同体积比的C3D／MCPA相比，K3D／MCPA的弯曲强度与弯曲模量均较低。     

低乙烯含量抗冲聚丙烯的结构表征

采用二甲苯为溶剂，将不同乙烯含量（５％￣１５％质量）的抗冲聚丙烯用特定程序进行分级，将各样品分为室温下可溶于甲苯和不可溶于甲苯的两部分。使用＾１３Ｃ－ＮＭＲ方法和ＦＴ－ＩＲ方法对各组分进行表征，明确了乙烯链段在聚丙烯链上的分布，并在此基础上提出了产生这种链结构的聚合工艺的特点。     

Gelling of alginate fibres

Equipment was developed to measure the time for complete gelling of sodium alginate fibres in calcium chloride solution, taken as the time to achieve maximum tensile strength. The effects of fibre diameter, alginate concentration, alginate composition and calcium chloride concentration on gelling time were investigated. A diffusional model, developed to predict the gelling time, agreed with experimental results except for the effect of calcium ion concentration which was modelled empirically.     

镀铜／镍聚丙烯腈纤维填充复合材料电磁波屏蔽性能的研究

研究了镀铜／镍的聚丙烯腈纤维填充ＡＢＳ树脂制得的复合材料的导电性及电磁波屏蔽性能，复合材料的导电性主要与导电纤维的填加量有关，导电纤维与基体树脂间的相容状况、复合加工时某些工艺条件等对复合材料的导电性也有较大的影响，电磁波屏蔽性能随导电纤维填加量的增加而提高，加入适当的偶联剂有助于改善和复合材料的电磁波屏蔽性能。     

马来酸及其酐和衣康酸与PP熔体接枝反应机理的研究

以马来酸酐作对照，用热分析、流变、化学分析等方法，研究了马来酸和衣康酸在非隔氧条件下与ＰＰ熔体催化接枝反应的特点和规律，阐述了单体结构－单元反应相对速率－－接枝产物结构之间的关系，提出了３种接枝物的结构模型。     

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。     

Experimental evaluation of the strength distribution of E-glass fibres at high strain rates

A bimodal Weibull distribution function was applied to analyse the strength distribution of glass fibre bundles under tensile impact. The simulation was performed using a one-dimensional damage constitutive model. The results show that there were two concurrent flaw populations in the fracture process. The regression analysis using the bimodal Weibull distribution function was in good agreement with experiment.