含环氧基聚硅氧烷的研究进展

含环氧基聚硅氧烷作为一类新型的功能高人子近年来受到了人们的关注。着重介绍含环氧基聚硅烷的种类、制备方法、性能特点等。     

老化对环氧化天然橡胶分子结构及性能的影响

老化对环氧化天然橡胶分子结构及性能的影响;环氧化天然橡胶;老化;结构;分子量;性能     

环氧化天然橡胶中环氧基团分布情况的研究

通过在胶乳状态下原位生成过氧甲酸制备环氧化天然橡胶（ENR）,采用傅里叶变换红外光谱（FRIR）对环氧化天然橡胶的结构进行表征,核磁共振谱仪（NMR）和差示扫描量热仪（DSC）对环氧基团的分布进行了研究,结果表明,过氧甲酸能迅速地渗透到橡胶粒子的内部,使环氧化基团分布在整个橡胶粒子上,环氧基团在ENR分子链上是无规分布...     

环氧天然橡胶接枝高分散白炭黑增强天然橡胶复合材料的制备及表征

基于白炭黑表面硅羟基与环氧基团的可反应性,利用Haake流变仪的高温高剪切作用,在170℃下,实现了环氧天然橡胶(ENR)对白炭黑的固态原位接枝,制备出一种高分散疏水型白炭黑.探讨了白炭黑和ENR的反应配比对增强性能的影响,确定合适的反应比例为3∶1.FTIR、TGA和TEM的分析结果证实了ENR被接枝到白炭黑表面上.对比研究了接枝前、后白炭黑对增强天然橡胶(NR)复合材料性能的影响,测试结果表明接枝白炭黑在天然橡胶中具有良好的分散性并能明显改善对天然橡胶的增强效果;接枝于白炭黑表面上的环氧天然橡胶分子玻璃化转变向高温偏移,使该复合材料在常温下具备优异力学性能的同时也体现出了高动态滞后的特点.     

硫化环氧天然橡胶的热分析

环氧化天然橡胶;热重分析;动力学;硫化环氧天然橡胶的热分析     

双键型分子光开关的E/Z异构化

适当取代的双键X=Y双键型分子能够在光的作用下发生E型和Z型之间的异构化。目前已报道的分子光开关大多是基于偶氮苯(ABs)、二芳烃乙烯(DAEs)和螺吡喃(SPs)等结构,但新的有趣的结构正在不断被报道。本文将讨论围绕C=C、C=N和N=N双键异构化的各种类型的光开关,重点介绍常用的光开关双键结构和极性质子溶剂等外界因素对其E/Z异构化的影响。     

柔性链高聚物的单分子链玻璃体和单晶*

本文综述了高分子单链颗粒的制备方法, 包括极稀溶液喷雾法、表面扩张膜法、冷冻干燥法、微乳液聚合法等。介绍和讨论了单链和寡链聚苯乙烯玻璃体微球的性质以及聚环氧乙烷、全同立构聚苯乙烯、顺-1, 4-聚丁二稀、反-1, 4-聚异戊二烯单链单晶电子显微镜和选区电子衍射观察的最新结果。     

溶剂沸点对聚(3-己基噻吩)薄膜内链结构与分子取向的影响

以聚(3-己基噻吩)(P3HT)为研究对象,借助荧光相关光谱、紫外-可见光谱和掠角红外光谱考察了溶剂性质对旋涂膜内P3HT的链结构与分子取向的影响。结果表明:溶液中P3HT的分子链构象受溶解度的影响,当P3HT溶解在溶解性好的良溶剂中时,链构象更伸展;固体薄膜内P3HT的物理结构却不受其在溶剂中溶解度大小的影响而具有沸点依赖性,溶解在高沸点溶剂中的P3HT旋涂后,薄膜内P3HT主链平面性与π-π相互作用均得到提高;此外,溶剂沸点的增加导致分子取向由"面朝上"方式转变为"边朝上"方式。     

氨基富π电子醚链的合成与超分子性能研究

合成、表征了含氨基的富π电子醚链四甘醇-二(2-氨基-4-苄氧基)苯基醚(5),并与不同的缺π电子联吡啶环蕃CPQT、FCPQT、5FCPQT作用形成了新型准轮烷5.CPQT、5.FCPQT、5.5FCPQT。利用核磁共振技术研究了它们在温度和酸碱调控下的分子开关功能。     

纳米SiO2掺杂对石蜡基绝缘油散热性能改进的分子模拟研究

利用分子模拟方法,建立纯石蜡基油模型和不同纳米SiO2掺杂浓度的石蜡基油模型,通过分子动力学计算得到各个模型的热导率、热扩散系数和介电常数等参数.在此基础上分析不同质量浓度SiO2掺杂下,石蜡基油的散热性能、流动性能和介电性能的变化规律.研究表明,随着掺杂SiO2质量浓度的提高,石蜡基油的黏度也随之提高,但仍与纯油黏温...     

胶乳法溴化天然橡胶的结构与性能

在胶乳状态下制得不同溴含量的溴化天然橡胶产物,并采用傅里叶红外光谱和1H NMR核磁共振测试技术对胶乳法溴化天然橡胶（BNR）的结构进行了表征,用扫描电子显微镜对BNR的形貌进行了观察,考察了不同溴含量BNR的溶解性能和氮含量。红外光谱分析表明,天然胶乳溴化反应时发生了溴化取代和加成反应;1H NMR分析结果则证实存在C=C双键加成和亚甲基、甲基的溴化取代。 随着溴含量的增加,BNR产物逐渐变得硬而脆,最终呈粉末状,且粒径减小。 同一溴化天然橡胶产物在不同溶剂中的溶解能力由小到大依次为：四氯化碳、苯＜甲苯、二甲苯＜四氢呋喃＜三氯甲烷＜环己酮;在同一有机溶剂中BNR的溶解性能则随着溴含量的增加而增大。 BNR产物的含氮量随着溴含量的增加而减小,当溴含量为42％时,氮含量减小至0.10％。     

Effects of Epoxidation Content of ENR on Morphology and Mechanical Properties of Natural Rubber Blended PVC

This research work has concerned a study on toughness of PVC/natural rubber (NR) blends compatibilized with epoxidized natural rubber (ENR). The aim of this work was to investigate the effect of degree of epoxidation on morphology and mechanical properties of the blends. Epoxidized natural rubber with a variety of epoxidation contents were prepared by reacting the NR latex with formic acid and hydrogen peroxide at various chemical contents. Chemical structure and epoxidation content of epoxidized natural rubber were evaluated by FTIR and ¹H-NMR techniques. After that, three grades of ENR with epoxidation contents of 15, 25 and 42 % (by mole) were further used for blending with PVC and NR in an internal mixer at 60 rpm and at 170 °C. From tensile and impact tests, it was found that tensile elongation and impact strength of the materials remarkably increased with degree of epoxidation. On the other hand, tensile strength and modulus of the materials rarely changed with the epoxidation content. An increase in toughness of the blends with epoxidation content was related to a better molecular interaction between PVC and ENR as suggested by torque-time curves of the materials.     

Some Synergistic Effects of Antioxidants in Natural Rubber

Some synergistic effects of antioxidants in natural rubber were investigated considering results obtained by differencial scanning calorimetry (DSC). Rubber formulations were obtained with mixtures of diaminic(DPPD, IPPD, HPPD) and monoaminic (ADPA, PBN) stabilizers and evaluated. The samples containing the mixture diamine/ADPA stabilizers showed synergistic effects while, for those containing diamine/PBN, no effect was observed. Additionally, the diffusion constants determined by use of vulcanized rubber disks confirmed the molar mass dependence of the stabilizer. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular Structures and Mechanical Properties of Microbe Rapid Coagulation Natural Rubber

In this work,molecular structures,dynamic mechanical properties and glass transition temperatures of microbe coagulated natural rubber(NR) samples were analyzed by using pyrolysis gas chromatography-mass spectrometry(py-GC/MS),rubber process analyzer(RPA) and dynamic mechanical thermal analysis(DMA).And the cross-linked network structures and mechanical properties of the corresponding NR vulcanizates were further determined by using nuclear magnetic resonance(NMR) crosslink density spectrometer(XLDS-15) and universal testing machines.The results show that NR raw rubber produced by rapidly coagulated with microorganism exhibits a simple molecular structure composition and good dynamic mechanical properties,and the corresponding NR vulcanizates possess the aggregation structure of high cross-linked density,a high glass transition temperature of-61.5 ℃ and high mechanical properties(tensile strength reaches 25.2 MPa),as compared with that coagulated with acetic acid.     

遥爪型液体天然橡胶的合成与表征

以天然橡胶(NR)为原料,经环氧化反应在NR分子链上引入环氧基制得环氧化天然橡胶(1);1经裂解反应合成了端羰基液体天然橡胶(2);对2进行改性得到端羟基液体天然橡胶(3),其结构经1H NMR和IR表征。探讨了反应温度、时间、氧化剂用量和环氧化程度对2的黏均分子量(M珚η)的影响。结果表明,延长反应时间、升高温度和增加氧化剂用量均可有效降低2的M珚η;1的环氧化程度对2的M珚η具有决定性作用,可通过调节环氧化程度实现2的M珚η的可控性。     

硫化天然橡胶的本征自修复与固相回收加工

通过小分子模拟试验和应力松弛,发现甲基丙烯酸铜(MA-Cu)比氯化铜(CuCl_2)更适合用作硫化天然橡胶中二硫键交换反应催化剂,并且硫化天然橡胶中的二硫键交换反应需要在高于120°C的温度下才能高效进行,这保障了相关制品在较低温工作时的结构与性能稳定.进一步的实验结果表明,硫化天然橡胶在MA-Cu辅助作用下获得了多次自修复与固相回收加工性能,损伤自修复后的硫化天然橡胶与固相回收加工的再生硫化天然橡胶,其拉伸强度均可恢复到原始材料强度的80%左右.