近地轨道空间中硅橡胶类材料的环境适应性及老化

硅橡胶类材料具有良好的耐高低温性能、电气性能及耐辐射性能,因此广泛应用于航天器的密封、阻尼、胶接及涂层防护领域。本文介绍了大部分航天器所运行的近地轨道空间(LEO)环境的特点及硅橡胶类材料的真空性能、耐高低温性能、耐原子氧侵蚀性能及光/辐射老化性能等,并对未来空间级硅橡胶材料的发展提出了设想。     

交联聚离子液体的合成及质子传导性能研究

本文设计合成了四种具有超高质子传导性能的交联聚离子液体材料。采用红外、元素分析、X射线光电子能谱和扫描电镜等表征手段对所合成材料的化学组成及结构进行了解析;采用热分析技术对材料的热稳定性进行了研究;系统研究了在不同条件下所合成材料的质子传导性能。研究结果表明:所合成的系列聚离子液体材料具有交联的三维结构;优异的热稳定性,其分解温度均超过253℃,最高分解温度可达314℃。在80℃和98%相对湿度(RH)下,这些材料的最大质子电导率为1.89×10~(-2) S·m~(-1)。该类聚离子液体材料超高的质子传导性能和简易的合成工艺,为新型质子传导材料的发展提供了新的思路。     

电子束预辐照聚丙烯与丙烯酸的接枝共聚合

应用电子束预辐照的方法对丙烯酸与等规聚丙烯粉末的接枝共聚合进行了研究．讨论了辐照剂量、储藏时间、反应温度、Ｍｏｈｒ’ｓ 盐浓度及单体浓度等因素对接枝率的影响（ 所有的实验,辐照及接枝聚合等都是在有氧的条件下进行的） ．同时对接枝材料对金属离子的吸附性能作了初步的探讨．结果表明,接枝聚合可以在有氧的条件下顺利进行．接枝材料在离子吸附方面有较大的应用前景．     

快离子导体系统中Li+运动的7Li NMR研究

Lil＋2。TiZ。Mg。P3012是一种具有较高离子导电车的快离子导体材料，其结晶化学和电导性能都已经进行了深入的研究，表明化合物具有规整的三维骨架结构，h离子位于骨架间隙中，并且其离子电导率随温度升高而增加＊．作者曾应用”P固体高分辨NMR技术对该固港体系统的微观晶体结构进行了研究，分析了Mg’“离子部分替代Ti‘“离子后，化合物骨架结构的特征＊．但对该体系的Li离子微观动态行为的研究还没有开展，在这里我们应用、i固体NMR技术研究了L计的状态及其动态行为，在此基J由上分析了Li离子可能的迁移机理．1实验部分’LiNMR…     

真空紫外辐照对加成型硅橡胶光学性能的影响

考察了加成型硅橡胶在真空环境中经1000ESH紫外辐照后的性能变化。结果表明,辐照后材料均出现发黄的现象,光学透过率大幅度 下降,同时加入硅酸钾包覆后制备的热控涂层反射率下降。经原位测试与离位测试,发现加成型硅橡胶在两种不同条件下测得的结果差异较小,而在有机硅橡胶中加入ZnO后原位与离位测试结果则差异明显,表现出明显的漂白作用。     

侧链结构对磺化聚芳醚性能及微观形貌的影响

比较了3种主链结构相同而侧链结构不同的磺化聚芳醚(SPAE)材料的性能. 分析了侧链结构对聚合物的吸水、 溶胀及质子传导行为的影响. 结果表明, 在相同的离子交换容量(IEC)条件下, 具有柔顺脂肪族侧链的聚芳醚材料具有较高的质子传导率. 其原因是由于柔顺的脂肪族侧链比刚性的芳香族侧链更易运动, 有利于侧链末端磺酸基团的聚集, 进而形成离子簇. 3种聚合物微观形貌的分析结果表明, 含柔顺侧链结构的聚合物薄膜具有更大的质子传输通道, 其结果与聚合物的宏观吸水和传导现象相吻合.     

模拟空间原子氧辐照下X射线光电子能谱仪的原位表征功能开发

对现有的X射线光电子能谱仪进行功能开发,在不改变仪器工作原理、不影响现有功能的前提下,将研制的空间交变温度原子氧辐照装置集成到其快速进样室,重点解决集群结构的匹配和性能兼容问题,实现模拟空间交变温度原子氧辐照环境下材料的原位表征功能.采用Kapton膜的质量损失方法测试空间交变温度原子氧辐照装置的原子氧通量密度,氧气流量、偏压和微波电流均对原子氧通量密度有较大影响.系统测试表明,原子氧辐照使WS 2薄膜表面发生了严重氧化,影响了薄膜的化学组成.不同温度原子氧辐照导致了不可忽略的化学组成与结构的差异.     

质子导体BaCe_(0.8)Lu_(0.2)O_(3-α)的电性能(英文)

采用高温固相法制备了BaCe0.8Lu0.2O3-α质子导体。运用X射线衍射仪(XRD)、扫描电镜(SEM)对该材料的物相结构、微观形貌进行了表征。在500~900℃温度范围内,应用交流阻抗谱和气体浓差电池方法研究了材料在不同气体气氛中的离子导电性和氢-空气燃料电池性能。结果表明,BaCe0.8Lu0.2O3-α材料为单一斜方晶结构,具有良好的致密性。在500~900℃温度范围内,干燥或湿润的氮气、空气和氧气中,材料的电导率随着氧分压增大稍有增大。在湿润的氢气中,材料表现为纯的质子导电性。在以该材料为固体电解质的氢-空气燃料电池条件下,材料表现为质子、氧离子和电子的混合导电性,其中离子导电性始终占主导;氢-空气燃料电池在900℃下的最大输出功率密度为92.2mW·cm-2,高于我们以前报道的BaCe0.8RE0.2O3-α(RE=Pr,Eu,Ho,Er,等)材料。     

白炭黑增强型硅橡胶的组成及抗原子氧性能分析

为明确空间级硅橡胶的化学组成及填料添加对材料物理性能的影响, 采用填料复合方式制备硅橡胶高聚物材料, 并通过化学成分测试、 原子氧暴露试验及力学性能测试等研究其结构组成与物理性能. 经微观粒径测试得出硅橡胶中白炭黑填料粒径主要分布在8~16 μm; 经傅里叶变换红外光谱(FTIR)、 核磁共振波谱( ¹H NMR和 ²⁹Si NMR)和溶胶凝胶渗透色谱(GPC)测试得出硅橡胶中含有Si—Me, Si—Ph, Si—O—Si等基团和甲基、 苯基等官能团, 其分子量分散系数为1.56, 并进一步推断出硅橡胶的分子结构及基胶与交联剂的反应类型为脱羟胺型; 经原子氧暴露试验及力学试验证实, 与未改性白炭黑填充的硅橡胶高聚物材料相比, 经硅烷改性白炭黑填充的硅橡胶高聚物材料表现出更好的抗原子氧性能, 动态力学测试后储能模量高54%, 并具有更好的应力应变响应性能. 研究结果表明, 采用表面改性处理方式可增强填料与硅橡胶基质的相互作用, 从而提高填料复合型硅橡胶高聚物材料的抗原子氧性能及综合力学性能.     

交流电晕对高温硫化硅橡胶性能的影响

采用针-板电极交流电晕放电试验装置研究了电晕放电对高温硫化硅橡胶憎水性、不同温度下憎水恢复性、力学性能和电气性能的影响,结果表明电晕放电作用不同时间后高温硫化硅橡胶材料憎水性丧失是一个渐进的过程,严重时硅橡胶材料憎水性会暂时性丧失,硅橡胶材料在不同温度下憎水性恢复速度不同,电晕放电作用后硅橡胶材料憎水接触角不能恢复至新试样初始水平.电晕放电不同时间后硅橡胶材料表面受电晕放电影响的范围逐渐扩大,表面产生了黑色粉末状电晕环,前期发展较快,然后逐渐由表层损坏转为纵深方向发展,材料表面和内层均可能遭到不同程度电蚀损,硅橡胶主链基团Si—O—Si、侧链基团Si—CH3和甲基中C—H键相对强度均随着电晕放电作用时间的增加呈下降趋势,材料拉伸强度和硬度有所下降,介电性能明显下降.     

DAMAGE OF SILICONE RUBBER INDUCED BY PROTON IRRADIATION

In this paper, the damage to methyl silicone rubber induced by irradiation with protons of 150 keV energy wasstudied. The surface morphology, tensile strength, Shore hardness, cross-linking density and glass transition temperaturewere examined. Positron annihilation lifetime spectrum analysis (PALS) was perfomed to reveal the damage mechanisms ofthe rubber. The results showed that tensile strength and Shore hardness of the rubber increased first and then decreased withincreasing irradiation fluence. The PALS characteristics τ_3 and I_3, as well as the free volume V_f, decreased with increasingirradiation fluence up to 10~(15) cm~(-2), and then increased slowly. It indicates that proton irradiation causes a decrease of freevolume in the methyl silicone rubber when the fluence is less than 10~(15)cm~(-2), while the free volume increases when thefluence is greater than 10~(15)cm~(-2). The results on cross-linking density indicate that the cross-linking induced by protonirradiation is dominant at smaller proton fluences, increasing the tensile strength and Shore hardness of the rubber, while thedegradation of rubber dominates at greater fluence, leading to a decrease of tensile strength and Shore hardness.     

Effect of 200 keV proton irradiation on the properties of methyl silicone rubber

The effects of 200 keV proton irradiation on methyl silicone rubber were studied. The changes in surface morphology, mechanical properties, cross-linking density, glass transition temperature, infrared attenuated total reflection spectrum and mass spectrum indicated that, at lower fluence, the proton irradiation induced cross-linking, resulting in an increase in tensile strength and hardness of the methyl silicone rubber. However, at higher proton fluence, radiation-induced degradation, which decreased the tensile strength and hardness, became dominant. A macromolecular-network destruction model for silicone rubber irradiated with protons was proposed.     

Optimisation of physical and mechanical properties of rubber compounds by response surface methodology--Two component modelling using vegetable oil and carbon black

Response surface methodology was used for predicting the optimal composition of vegetable oil and carbon black in rubber compounding. Central composite rotatable design for two variables at five levels was chosen as the experimental design. The data obtained from measurement of properties was fitted as a two variable second order equation and were plotted as contour plots using programme developed in MATLAB v.5. It is observed from the contour plots that the increase in cross-link density caused by the formation of rubber mono-layer from its multi-layer on increasing the carbon black loading upto the central point (50 phr) of experimental region increases 300% modulus and elongation at break and reduces the ultimate properties like tear strength and tensile strength. On the other-hand hardness increases with increase in solid inclusion of carbon black. From the contours it is observed that the addition of vegetable oil upto 2-3 phr, cross-link density increases due to its coupling action leading to increase in hardness and modulus and lowering of ultimate properties like tensile strength and elongation at break. Addition of further amount of vegetable oil shows less coupling and more plasticising effect leading to increase in tear strength, tensile strength and elongation at break and decrease in hardness and 300% modulus.     

硅氢加成型室温固化硅橡胶胶粘剂的研究

<正> 我们研制了一种硅氢加成型室温固化硅橡胶,这种橡胶不但有较好的力学性能,而且与各类材料如金属、塑料、陶瓷、玻璃等都有很好的粘结力,是一种具有弹性的胶粘剂。该胶粘剂是利用一种含乙烯基聚硅氧烷、含氢聚硅氧烷以及二氧化硅补强剂在铂催化剂     

The effect of grass fiber filler on curing characteristics and mechanical properties of natural rubber

Natural rubber is reinforced with a novel type of grass fiber (Cyperus Tegetum Rox b). The effects of fiber loading of different mesh sizes on curing characteristics and mechanical properties of grass fiber filled natural rubber composite are studied. Since 400 mesh grass fiber loaded natural rubber composite shows superior mechanical properties, therefore the effect of silane coupling agent was studied for this particular composite. Here composites were prepared by using water leached grass fiber. Optimum cure time increases with the increase in fiber loading but the change in scorch time is less. The same trend of increase in optimum cure time is observed in the presence of Si69. But the value is higher compared to that of rubber composite without Si69. With increase in the fiber loading, modulus and hardness of the composite increases but tensile strength decreases. The mechanical properties of the composite, namely moduli at 200 and 300% elongation and hardness increase in the presence of Si69 but tensile strength is less compared to that of the composite without Si69. Elongation at break is not much affected due to the presence of Si69. Copyright © 2004 John Wiley & Sons, Ltd.     

The influence of nano silica particles on gamma-irradiation ageing of elastomers based on chlorosulphonated polyethylene and acrylonitrile butadiene rubber

The goal of this work was to study gamma irradiation ageing of rubber blends based on acrylonitrile butadiene rubber (NBR) and chlorosulphonated polyethylene rubber (CSM) reinforced by silica nano particles. The NBR/CSM compounds (50: 50, w/w) filled with different content of filler (0–100 phr) were crosslinked by sulfur. The vulcanization characteristics were assessed using the rheometer with an oscillating disk. The vulcanizates were prepared in a hydraulic press. The obtained materials were exposed to the different irradiation doses (100, 200, 300 and 400 kGy). The mechanical properties (hardness, modulus at 100% elongation, tensile strength and elongation at break) and swelling numbers were assessed before and after gamma irradiation ageing.     

碳酸钙与碳化硅对室温硫化硅橡胶的补强作用

在有关硅橡胶补强的研究中,人们已经对ＳｉＯ２ 等补强性填料对硅橡胶的补强作用进行了深入的研究,但对非补强填料对室温硫化硅橡胶的补强作用则相对涉及较少．作者研究了ＣａＣＯ３ 和ＳｉＣ 两类非补强性填料以及填料的粒径与分布对室温硫化硅橡胶拉伸强度、断裂伸长率和耐温性能等的影响,发现合适粒径的非补强性填料对室温硫化硅橡胶有较好的补强效果,且在填料粒径及分布匹配时有最好的补强效果,选用ＳｉＣ时还可以有效提高室温硫化硅橡胶的热稳定性．     

A new cross‐linked system of silicone rubber based on silicone‐polyurea block copolymer

A new cross‐linked system of silicone rubber (SR) was obtained from silicone‐polyurea block copolymers that was synthesized with aminopropyl terminated polydimethylsiloxane and (4‐isocyanatocyclohexyl)‐methane. SR possessed self‐reinforced and physical cross‐linked structure. It had better mechanical properties that the hardness, the tensile strength, and the elongation at break could reach 65 Shore A, 3.78 MPa, and 458% with the polyurea segment content ranging from 2.01% to 9.13% by weight . The hydrogen bond that led to the physical cross‐linked structure was proved byFourier transform infrared spectroscopy. The microphase separated structure that caused the self‐reinforcement was illustrated by scanning electron microscopy, X‐ray diffraction analysis, and dynamic mechanical analysis. Fourier transform infrared spectroscopy results showed the hydrogen bond formation between the polyurea units. Scanning electron microscopy, dynamic mechanical analysis, and X‐ray diffraction analysis results proved the microphase separation existed between polyurea units and ―Si―O―Si― chains. The increase of polyurea contents enhanced the binding of hydrogen bond and improved the extent of microphase separation. Accordingly, it decreased the thermal properties and lowered the glass transition temperature (T_g) from −108°C to −114°C. Also, the increase of polyurea contents increased the hydrophobicity of SR that the surface free energy could reach to −24.81 mN/m.     

Effect of Electron Beam Irradiation on the Properties of High Styrene Rubber/Styrene Butadiene Rubber Blends

High styrene rubber (HSR)/styrene butadiene rubber (SBR) blends at different ratios were exposed to various doses of electron beam irradiation. The effect of irradiation dose and blend ratios on the mechanical properties and shape memory characteristics in terms of strain fixation) rate (R_f) and strain recovery rate (R_r) was investigated. The results revealed that rich styrene blends displayed higher tensile strength and hardness than low styrene content blends at all irradiation doses. However, elongation at break, and toughness were lower for rich styrene content. Also, it was observed that for most specimens, the tensile strength, elongation at break and hardness increases up to100 kGy. Increasing irradiation doses resulted in slight deterioration in some mechanical properties only for low styrene content at150 kGy. According to the normalized tensile stress at 25% elongation, it was found that the contribution of irradiation in enhancing the mechanical properties is higher for rich butadiene blends. On the other hand, it was observed that rich styrene content blends possess higher R_f and R_r at all the irradiation doses and stretching temperatures. However, the increase of irradiation dose decreases R_f values; the extent of this decrease depends on the blend ratios. Conversely, for all blends, R_r were increased by increasing irradiation dose and styrene content ratios.