PDMDAAC-AM共聚物的反相乳液聚合研究

研究了用二甲基二烯丙基氯化铵(DimethylDiallylAmmoniumChloride，DMDAAC)和丙烯酰胺(Acylamide，AM)为原料。以煤油为分散剂，在反相乳液环境中合成PDMDAAC-AM(Poly DMDAAC—AM)的方法．从反相乳液聚合的机理出发。研究了油水体积比、引发剂的用量、单体配比、引发温度和反应温度等因素对共聚产物的特性黏度和转化率的影响，确定了最佳反应条件．在DMDAAC／AM=2：8，油水比为3：7，采用过硫酸钾为引发剂，其用量为体系总质量的0．05％的条件下，采用逐步聚合的方法得到了固含量为45％，特性黏度为800．5cm^3／g，溶解迅速且絮凝效果好的产品．     

一种羟基改性的氯乙烯-醋酸乙烯共聚树脂的均相合成

采用均相法对氯乙烯 -醋酸乙烯酯二元共聚树脂进行了羟基改性研究。文中考察了反应温度θ、反应时间t、碱与二元氯 -醋共聚树脂的质量比、溶剂甲醇与二元氯 -醋共聚树脂的质量比、加料方式等因素对三元共聚物中羟基含量的影响。在t=5h,θ=40℃ ,ω(NaOH) :ω(氯 -醋二元共聚树脂 )=0.012:1,ω(甲醇 ) :ω(氯 -醋二元共聚树脂 )=1:3.5,R=300r/min的条件下 ,可得到与进口产品———美国UCC公司VAGH树脂组成接近的共聚物     

铈离子引发罗布麻接枝共聚反应──单体活性比较

本文采用丙烯酸甲酯（ＭＡ）、丙烯酸乙酯（ＥＡ）和丙烯酸丁酯（ＢＡ）．用铈离子引发将其与罗布麻纤维接枝共聚。结果表明：当［Ｃｅ４＋］为１０×１０－２ｍｏｌ／Ｌ、［Ｈ＋］为８×１０－２ｍｏｌ／Ｌ、［Ｍｏ］为１２×１０－２ｍｏｌ／Ｌ、４０℃反应３小时可得最大接枝率。在本文实验条件下，单体反应活性顺序为ＭＡ＞ＢＡ＞ＥＡ。     

Mathematical Simulation of High-Conversion Binary Copolymerization

A new model for mathematical simulation of high-conversion binary copolymerization was established by combination of the concept of the three stage polymerization model (TSPM) proposed by Qin et al. for bulk free radical homopolymerization with the North equation to describe high-conversion copolymerization reaction exhibiting a strong gel effect, and the mathematical expressions of this new model were derived. Like TSPM, the new model also assmnes that the whole course of binary copolymerization can be divided into three different stages: low conversion, gel effect and glass effect stages. In addition, the reaction rate constants and the initiator efficiency at each copolymerization stage do not vary with conversion. Based on the expressions derived, a plot method for determining the overall rate constants and critical conversions was proposed. The literature data on conversion history for styrene (St)-methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA)-MMA copolymerizations were treated to examine the model, which shows that the model is satisfactory.     

Investigation on chain structure of LLDPE obtained by ethylene in-situ copolymerization with DSC and XRD

Thermal segregations of LLDPE were treated with successive self-nucleation/annealing (SSA) on dif-ferential scanning calorimetry (DSC). Information on molecular heterogeneity of LLDPE was obtained. After SSA was treated, the multiple endothermic peaks were observed in the DSC thermograms during heating experiment. It is obtained that the thickness of different lamellas formed by segments of vari-ous lengths was 4―10 nm. X-ray diffraction (XRD) results showed that the crystallites dimensions of various reflections were about several dozens of nanometers. The ethylene/α-olefin copolymers and the copolymer via in-situ copolymerization were similar to each other for molecular heterogeneity and XRD characteristics, which revealed that it was possible to use the ethylene/α-olefin copolymers to simulate the copolymer via in-situ copolymerization of ethylene to simplify the complexity of the structure of the ethylene in-situ copolymer.     

Preparation of PE/MMT nanocomposite by monomer intercalation and in situ copolymerization

The catalyst {[(2-ArN == C(Me)(2C5H3N]FeCl2} (Ar = 2-C6H4(i-Pr)) with methylaluminoxane (MAO) as cocatalyst was intercalated between layers of montmorillonite (MMT) for ethylene oligomerization. Metallocene catalyst Me2Si(Ind)2ZrCl2 and MAO was then added to form a dual functional catalytic system. A PE/MMT nanocomposite was prepared by copolymerization of ethylene with α-olefins produced in situ from ethylene over the dual functional catalytic system. The catalytic system was of high polymeric activity. The resultant PE/MMT nanocomposites were stable and got increases in tensile strength and temperature of maximum weight loss (Tonset).     

对称自对偶李代数的一些性质

给出一类带有非退化对称不变双线性型及对称自对偶李代数的分解唯一性的一个充分条件,并讨论此类李代数的特殊性质.     

纤维素与丙烯酸在氯化锌水溶液中的均相接枝

以质量分数为65%的氯化锌水溶液为反应介质、过硫酸钾为引发剂,研究了微晶纤维素(MCC)与丙烯酸(AA)的均相接枝共聚反应,考察了引发剂用量、引发时间、接枝共聚时间、单体用量等因素对接枝率的影响,并用FT-IR、XRD和TGA分析了接枝前后微晶纤维素的特性.结果表明:当引发剂与MCC的质量比为1∶2、单体与MCC的质量比为5∶1、引发时间为10 min、接枝共聚时间为8 h、共聚温度为60℃时,接枝率达20.3%;随接枝时间的延长,接枝产物粒径呈减小趋势,电位呈增加趋势;接枝后的产物在1729cm-1处有CO的吸收峰,说明接枝上了丙烯酸单体;接枝后MCC的结晶度及热分解温度均降低.     

Explicating formal epistemology: Carnap's legacy as Jeffrey's radical probabilism

Quine's “naturalized epistemology” presents a challenge to Carnapian explication: why try to rationally reconstruct probabilistic concepts instead of just doing psychology? This paper tracks the historical development of Richard C. Jeffrey who, on the one hand, voiced worries similar to Quine's about Carnapian explication but, on the other hand, claims that his own work in formal epistemology—what he calls “radical probabilism”—is somehow continuous with both Carnap's method of explication and logical empiricism. By examining how Jeffrey's claim could possibly be accurate, the paper suggests that Jeffrey's radical probabilism can be seen as a sort of alternative explication project to Carnap's own inductive logic. In so doing, it deflates both Quine's worries about Carnapian explication and so also, by extension, similar worries about formal epistemology.     

直肠癌手术中输尿管损伤的预防和处理

目的 :探讨在直肠癌根治术中引起输尿管损伤的治疗与预防 ;方法 :分析我院13a间行直肠癌根治术术中输尿管完全断裂损伤的5例病例 ,5例均为术中及时发现损伤并行吻合 ;结果 :无一例发生并发症 ,愈后较好 ;结论 :尽早发现处理和积极地预防是治疗直肠癌根治术中输尿管损伤的关键