c-BN对绝缘高导热硅橡胶性能的影响

采用聚二甲基硅氧烷基础胶、含氢硅油交联剂、立方氮化硼(c-BN)导热填料,制备了绝缘高导热硅橡胶;研究了c-BN的不同含量对硅橡胶导热性能、绝缘性能、物理性能的影响。结果表明:填充改性c-BN粉体可以大幅度提高硅橡胶体系的导热性能,在c-BN用量为80%时导热系数为7.16 W/(m·k),热阻为3.39 cm~2K/W;c-BN粉体会降低硅橡胶体系的绝缘性能和力学弹性,但当用量不超过80%时,击穿强度大于6 k V/mm、体积电阻率大于1×1012Ω·cm、硬度小于55、压缩永久变形小于30%,符合实际使用中的绝缘需要,符合产品安装和使用的条件,不易被压碎、压裂而且具有一定弹性。     

加成型交链聚硅氧烷玻璃毛细管柱（ACOT）的研制及评价

]本文介绍一种加成交链方法制备交链毛细管柱,此方法采用端基含乙烯基的低分子量的甲基乙烯基硅油和含氢硅油在微量铂催化剂作用下室温加成,交链同时伴有链增大,使低分子量硅油交链并聚合形成高热稳定性的硅弹性体。玻璃毛细管柱采用氟化氢铵蚀刻法进行表面粗糙化,玻璃表面钝化采用六甲基二氨硅烷（HDMS）和含氢硅油钝化方法并收到了较好的效果。采用此方法制备出的玻璃毛细管柱,非极性、中极性柱理论板数高达4000块／m,并可在320℃～340℃下程序升温使用,氰乙基硅橡胶柱程序升温可到260℃,经Grob混合物评价,吸附较小,是一种低流失,耐高温、液膜不可抽提的高效柱。     

双组份室温加成型硅橡胶口腔印模材料的制备

以自制乙烯基硅油为基胶、自制含氢硅油为交联剂、铂配合物为催化剂、高纯度硅微粉为填料、多乙烯基化合物为抑制剂等,通过实验制得双组份室温加成型硅橡胶口腔印模材料.研究了各组分对硅橡胶印模材料硫化化时间、细微复制、力学性能的影响.并制备了与国外产品性能相当的产品.     

交联补强硅橡胶包埋18-甲基炔诺酮的释放行为

甲基乙烯基硅橡胶;交联补强硅橡胶包埋18-甲基炔诺酮的释放行为;药物释放系统     

基于专业认证的高分子材料与工程实验的综合性设计实践

工程专业认证强调以学生为中心,注重培养学生解决复杂工程问题的能力,本文设计了一个综合性的高分子材料与工程实验——高温硫化甲基乙烯基硅橡胶的制备与性能测试.实验要求学生通过文献调研、小组讨论明确实验基本原理的基础上,自主设计实验方案,制备甲基乙烯基硅橡胶制品,测试硅橡胶生胶的分子量、热行为及硫化胶的基本力学性能,以科研论...     

四苯(基)苯基多乙烯基硅油的合成及结构测定

<正> 多乙烯基硅油是高温硫化硅橡胶的集中交联剂,当无耐热填料时,所得硫化胶的耐热性不高。为了使多乙烯基硅油既具有集中交联作用,又赋予耐热性,本文采用Diels-AIder反应合成了含有四苯(基)苯基的多乙烯基硅油。前文曾合成多种多苯(基)苯基有机硅化合物,但实验在封管内进行,诸多不便,投量也甚少,为此,改用高沸点溶剂(α-氯萘),在常压下反应,得到了高产率的四苯(基)苯基多乙烯基硅油:     

聚乙二醇/氮化硼复合材料相变导热性能及其结晶行为

本文采用熔融共混浇筑的方法制备了聚乙二醇/氮化硼(PEG/BN)相变复合材料,并研究了不同尺度片状BN对相变复合材料导热性能和结晶行为的影响。 通过扫描电子显微镜(SEM)、热常数分析仪、红外热成像分析仪和差示扫描量热仪(DSC)研究了相变复合材料的微观形貌、导热系数和相变过程,并利用莫志深法对DSC结果进行了非等温结晶动力学分析。 结果表明,较大片状直径(50 μm)的BN可以更有效地提高聚乙二醇的导热系数,当BN填料质量分数为40%时,相变复合材料的导热系数可达到5.04 W/(m·K)。 在快速降温条件下,片径为50 μm的BN填料可以缩短PEG的半结晶时间,提高结晶速率,使相变复合材料具有较大的相变焓。     

导热增强聚乙二醇相变复合材料的制备及其性能

本文以聚乙二醇(PEG)为相变材料,通过添加不同的无机填料,采用熔融共混浇筑方式制备了导热增强型相变复合材料。 通过扫描电子显微镜(SEM)、热常数分析仪、差示扫描量热仪(DSC)、红外热成像和热重分析仪研究了所制备复合材料的微观结构、导热性能与相变过程。 研究结果表明,相比于碳酸钙和氧化铝,在相同添加含量下,氮化硼(BN)可有效提高PEG的导热系数,当BN质量分数为40%时,导热系数可达到3.40 W/(m·K);当填料添加量相同时,片状BN和不规则纳米碳酸钙(CaCO₃)比球形氧化铝(Al₂O₃)对PEG具有更加优良的定型效果,在相变过程中,能够更加有效阻隔PEG的流动,保持复合材料的形状稳定性。     

^29SiNMR测定含氢硅油中Si—H键含量

聚二甲基甲基氢化硅氧烷(简称含氢硅油)是一类反应性有机硅聚合物。这类聚合物中含有的si—H键十分活泼,其化学性质在有机硅工业中十分有用,如合成不同类型的硅油、有机硅树脂、硅橡胶、改性有机硅表面活性剂等。     

有机硅氧烷乳液粒子粒径及其分布的测定

本文采用甲基环硅氧烷与乙烯基环硅氧烷共聚合的方法,制得了硅油轧液,利用乙烯基双键使聚合物硬化,以固定乳液颗粒,并用电子显微镜观察研究了液珠的组成及分布情况。发现阴离子硅油乳液颗粒较阳离子乳液的粒子细,且粒径分布窄。在阳离子硅油乳液中添加非离子乳化剂,或采用机械后乳化的方法,能消除大粒径的液珠,使其颗粒变小、变匀,从而大大改善阳离子乳液的稳定性。     

Furyl- and thienyl-silatranes and germatranes

We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992.     

Review and patents and literature

The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed.     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...     

Ground- and excited-state aromaticity and antiaromaticity in benzene and cyclobutadiene

The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei.     

微量元素与疾病诊断治疗的研究现状及展望

对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述，包括：微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。     

Preparation and photolysis of poly-p-ethylacrylophenone and poly-p-chloroacrylophenone and their copolymers with styrene and methyl methacrylate

Poly-p-ethylacrylophenone (PPEtAP) and poly-p-chloroacrylophenone (PPClAP) and their copolymers with styrene (PEtAP/S) and (PClAP/S) and with methyl methacrylate (PEtAP/MMA) and (PClAP/MMA) were prepared. Quantum yields of main-chain scissions at 366 nm at room temperature in benzene solution are of the same order as those of the unsubstituted polyacrylophenone and its copolymers. Substitution with chlorine and ethyl group in the para position compared to the unsubstituted polyacrylophenone and its copolymers leads to an increase of the lifetime for the n–π^* excited triplet state, as is evident from the measured quenching constants of photolysis. The low-temperature emission spectra of the copolymers are similar to the spectra of the model compounds in a polymer film. For the homopolymer, however, the character of the emission spectrum changes considerably.     

Concentrations and distributions of trace and minor elements in Chinese and Canadian coals and ashes

A total of 35 trace and minor elements including some of environmental significance were determined in each of a selection of 15 Chinese and 6 Canadian thermal coals and their ashes by using the SLOWPOKE-2 nuclear reactor facility of the University of Toronto. The concentrations and distributions of these constituents among the coals and their combustion products (viz. ash and volatile matter) are presented together with an interpretation of their significance in relation to the large scale combustion of these coals as thermal fuels in industrialized countries such as China and Canada. The detailed results showed wide variations in trace impurity concentrations (up to a factor of 100 and more) among the coals studied with few large differences between those of Chinese and Canadian origin except that the rare earths, Sc, Th, U, I, and Se were much higher in the former, other halogens, As and Na were lower. Values for elemental enrichment factors (EF) relative to normal crustal abundances indicated that only As(EF=13), Br(5.7), I(16), S(230), Sb(11) and Se(320) were appreciably enriched in coal. During static ashing at 750°C most of the halogens, S and Se were volatilized whereas most other inorganic constituents were highly retained and concentrated in the ash by factors of 6 to 11.