硅橡胶泡沫复合材料的制备、性能与应用

硅橡胶泡沫材料作为一种新型的聚合物泡沫体系,保持了硅橡胶材料的耐高低温、抗紫外线、化学稳定性等特点的同时,也具备泡沫材料柔性轻质、压缩回弹性好等优异特性。将功能填料引入到硅橡胶泡沫体系中可以获得特定功能的硅橡胶泡沫复合材料,已成为近年来的研究热点。综述了近年来国内外硅橡胶泡沫复合材料的进展,主要回顾了硅橡胶泡沫材料的制备方法,并分析了各种制备方法的优缺点;总结了硅橡胶泡沫复合材料力学、热学、阻燃和导电性能的研究现状;在此基础上,介绍了功能型硅橡胶泡沫复合材料在油水分离、传感器、生物医药等领域的应用前景。最后,展望了硅橡胶泡沫复合材料的发展趋势。     

聚硅倍半氧烷改性光固化硅橡胶绝热耐烧蚀材料

以"巯基-双键"交联体系为基础,室温光固化制备了硅橡胶绝热材料,并研究了新型耐烧蚀填料八苯基硅倍半氧烷(OPS)和八乙烯基硅倍半氧烷(OVP)对硅橡胶性能的影响。采用热重分析、力学测试、氧乙炔烧蚀、极限氧指数、锥形量热和扫描电镜对制备的硅橡胶进行了分析。结果表明,OPS和OVP都可以提高硅橡胶的热稳定性和耐烧蚀性,但对力学性能有一定影响。其中,OVP改性的硅橡胶表现出更佳的耐烧蚀性能,含有15 phr OVP的硅橡胶线烧蚀率为0.121 mm/s,相比纯硅橡胶降低了84.8%。添加OPS和OVP都能够显著延长硅橡胶的点燃时间(TTI),降低热释放速率峰值(P-HRR),改性硅橡胶燃烧后的炭层更加致密,且OVP的效果更佳。因此,聚硅倍半氧烷在硅橡胶绝热耐烧蚀材料领域中有很大的应用价值。     

硅橡胶在电气绝缘方面的应用进展

硅橡胶具有耐高温、耐寒、耐电晕，点绝缘性及化学惰性等卓越的特性，应用硅橡胶作电气绝缘材料，使电气设备系统更加完善。硅橡胶也非常适合应用于电气电工行业，硅橡胶用作绝缘材料，具有优良的抗紫外线和抗臭氧性能；优良的耐候性能和耐老化性能；耐电晕，高抗电痕性；持久的憎水性及憎水性迁移特性；对环境无害，环保无污染。通常把室温硫化硅橡胶、高温硫化硅橡胶、液态硅橡胶用作复合避雷针，断路器、变压器、互感器、高压开关和套管绝缘材料及硅橡胶电缆终端等。随着科学技术的发展，硅橡胶的应用前景将更加广阔。     

纳米改性材料对导电硅橡胶防腐特性的改善研究

利用纳米SiO2和石墨与炭黑并用填充硅橡胶基体制备了导电硅橡胶,利用酸、碱、汽油和甲苯对3种导电硅橡胶试样进行腐蚀处理,研究了纳米改性材料添加前后,导电硅橡胶试样机械性能和导电性能在腐蚀前后的变化情况。研究表明:导电硅橡胶耐强酸腐蚀能力较弱;添加改性材料后,导电硅橡胶试样抗腐蚀能力增强,机械性能稳定性增加;添加改性材料后,导电硅橡胶试样的压阻特性、弛豫性以及回滞性等性能腐蚀前后的变化程度降低,稳定性增加。     

基体结构与短纤维对硅橡胶耐烧蚀绝热材料性能的影响

采用甲基硅橡胶、乙烯基硅橡胶、甲基苯基乙烯基硅橡胶作为耐烧蚀绝热材料的基体,对其性能进行了研究,结果表明:甲基苯基乙烯基硅橡胶属于综合性能较好的成碳型绝热材料基体。以甲基苯基乙烯基硅橡胶为基体,制备短切玻璃纤维、短切碳纤维和聚芳砜纶浆粕增强耐烧蚀绝热复合材料材料,对其物理性能、导热性能及耐烧蚀性能进行了系统研究。结果表明不同纤维的增强效果差别较大,相同用量条件下,PSA浆粕增强制得的复合材料线烧蚀率较低(0.086mm.s-1);从综合性能及碳层结构方面考虑,玻璃纤维与PSA浆粕可以作为苯基硅橡胶耐烧蚀绝热材料的成碳增强材料。     

硅橡胶在电线和电缆中的应用

美国硅橡胶每年销售量约为6亿美元,是其化学工业中利润最高的部门之一。因为硅橡胶具有好的热稳定性、优异的电性能、阻燃性、优良的耐环境性能和高的热导率,它在电线电缆工业中的应用不断增长。历年来硅橡胶的增长率一直是约每年15～18％,其中硅橡胶电线和电缆的增长尤其迅速。硅橡胶电线和电缆的最大市场之一是汽车工业。据通用电器公司硅橡胶产品部     

有机硅改性环氧树脂制备耐核辐射涂料及其性能研究

采用自制有机硅改性环氧树脂、自制改性脂环胺固化剂和功能性填料制备了适用于AP1000核电站的耐核辐射涂料,采用扫描电子显微镜、差示扫描量热仪对漆膜进行表征,研究了有机硅改性环氧树脂在耐核辐射涂料中的作用及其对漆膜性能的影响。结果表明:有机硅改性环氧树脂及改性脂环胺固化剂配制的耐核辐射涂料具有优良的附着力、耐化学品性、抗辐射性能及施工性能。     

国家标准《核电站用1E级电缆通用要求》解读和分析

<正> 前言核电站1E级电气系统和设备是指完成反应堆紧急停堆、安全壳隔离、堆芯应急冷却,以及反应堆和反应堆厂房的余热排出以及防止放射性物质向周围环境大量排放等功能的电气系统设备。核电站用1E级电缆通常包括电力电缆、控制电缆、信号电缆、仪表电缆、热补偿电缆、光缆等种类。《核电站用1E级电缆通用要求》主要规定了核电站1E级电缆的类别、一般     

加成型硅橡胶耐漏电起痕性能的影响因素探讨

研究了不含ATH的硅橡胶体系中,交联密度、硅氢与乙烯基比例(Si-H/Vi)对加成型硅橡胶耐漏电起痕性能的影响。研究结果表明:保持Si-H/Vi(摩尔比)在2~3之间时,采用VMQ硅树脂提高体系的乙烯基含量,调节硅橡胶交联密度,可使加成型硅橡胶同时具有良好的机械性能和耐漏电起痕性能。     

纳米粒子增强RTV-SR的研究进展

概述了室温硫化硅橡胶的种类、性能及其应用,综述了国内外无机纳米微粒对室温硫化硅橡胶的增强研究进展,重点介绍了室温硫化硅橡胶增强机理及补强方法,作为填料的无机纳米微粒的种类,指出了无机纳米填料的发展方向主要是采用原位复合技术制备出硅橡胶纳米复合材料.     

耐漏电起痕硅橡胶的制备及应用研究进展

硅橡胶以其优异的电气绝缘性、憎水防污和耐污闪等性能而广泛应用于高压超高压电力电气设备及外绝缘领域。然而硅橡胶绝缘材料在长期使用过程中,在外界强电场放电作用下会发生漏电起痕破坏,致使材料失效甚至燃烧。这对电力系统与电气设备的安全运行,以及人们的生产和生活造成巨大的危害。因此,硅橡胶的耐漏电起痕研究吸引了越来越多研究者的关注。文中综述了近年来国内外关于耐漏电起痕硅橡胶的最新研究进展,分析了硅橡胶耐漏电起痕剂亟待解决的问题,并指出高效率、相容好、多功能的有机耐漏电起痕剂是耐电痕化硅橡胶的重要发展方向。     

纳米TiO2/液体硅橡胶直流电缆附件绝缘复合材料的介电性能

高压直流电缆附件在电力系统运行中,由于复合绝缘电导率不匹配极易导致电场畸变引发绝缘故障。针对这一问题,采用直接共混法制备了不同掺杂浓度的纳米TiO₂/液体硅橡胶（LSR）复合材料,并对其微观形貌和介电性能进行了测试研究。结果表明:纳米TiO₂粒子在LSR基体中分散较均匀,随着TiO₂掺杂含量的增加,纳米TiO₂/LSR复合材料试样的相对介电常数和介质损耗因数增大。当纳米TiO₂粒子添加量为4wt%时,纳米TiO₂/LSR复合材料的电导率与电缆主绝缘交联聚乙烯（XLPE）的电导率近似相等,且随着电场强度的增大,两者的电导率变化趋势也基本一致。电声脉冲法（PEA）测量结果表明,添加4wt% TiO₂的纳米TiO₂/LSR复合材料内积聚的空间电荷最少。纳米TiO₂粒子的掺杂,提高了TiO₂/LSR复合材料电缆附件绝缘电导率对电场强度的响应依赖特性,使其能与XLPE绝缘电导率较好地匹配,同时一定程度地抑制了空间电荷的积累,有助于直流电缆附件内复合绝缘电场的均匀分布。      

钛酸铜钙纳米纤维/液体硅橡胶复合介质非线性电导性能

为解决直流电缆附件内因温度梯度和材料电导率差异而引起的局部电场畸变的难题,本文通过静电纺丝方法制备了钛酸铜钙（CaCu₃Ti₄O₁₂）纳米纤维,并将其分散在液体硅橡胶中合成了具有非线性电导特性的CaCu₃Ti₄O₁₂纳米纤维/液体硅橡胶复合介质。采用XRD和SEM对CaCu₃Ti₄O₁₂纳米纤维和CaCu₃Ti₄O₁₂纳米纤维/硅橡胶复合介质进行微观结构表征,并对CaCu₃Ti₄O₁₂纳米纤维/硅橡胶复合介质的介电特性、空间电荷特性及在30℃、50℃、70℃条件下电导率随电场强度变化规律和击穿强度进行测试,最后建立电缆附件模型,并对附件应力锥根部电场进行仿真。结果发现:CaCu₃Ti₄O₁₂纳米纤维/硅橡胶复合材料的介电常数和电导率都随着CaCu₃Ti₄O₁₂纳米纤维含量的增加而增大,当纳米纤维达到3vol%时复合介质的相对介电常数增加到3.27,非线性电导率也变化了近4个数量级,经过空间电荷测试发现,空间电荷的消散量与CaCu₃Ti₄O₁₂纳米纤维含量也正相关,复合材料的直流击穿强度随纳米纤维含量的增加而降低,通过对附件进行稳态电压作用下的电场分布仿真分析发现,当CaCu₃Ti₄O₁₂纳米纤维的含量为2vol%时,应力锥根部最大电场强度已经从增强绝缘中转移到电缆主绝缘中,在正、反极性雷电冲击电压作用下,3vol%含量的CaCu₃Ti₄O₁₂纳米纤维/硅橡胶复合介质作为增强绝缘材料时最大电场强度均远远低于其击穿强度。以上实验结果表明,CaCu₃Ti₄O₁₂纳米纤维作为填充相在较低的掺杂浓度实现了对液体硅橡胶的改性,满足了复合介质应用于电缆附件的电气绝缘性能需求。      

石墨烯硅橡胶复合材料的性能研究

本文采用复配的石墨烯、碳纳米管和氧化铝为导热填料制备了具有导热功能的有机硅复合材料。研究了石墨烯、碳纳米管和氧化铝的复配比例对复合材料体积电阻率、导热系数、拉伸强度等性能的影响;同时,以Gr-C-4#样品为基础配方,采用硅烷偶联剂Si-G-1分别对石墨烯、碳纳米管及氧化铝进行改性,并用改性后的填料配制石墨烯硅橡胶复合材料Gr-C-Si-1#,对比样品Gr-C-4^#与Gr-C-Si-1^#的性能差异,分析了改性复配填料对复合材料性能的影响。采用石墨烯硅橡胶复合材料对电缆终端进行了封装,对封装好的电缆终端开展了100、150、200A电流下的温升实验,未出现局部过热,并测定水浸泡前后的电缆终端电阻,封装后的电缆终端电阻未出现明显上升,实验结果表明本材料可以在电缆终端或中间连接处进行灌封,可对封铅连接处的良好的保护作用,工程应用意义重大。     

Electrical properties of flexible polypropylene based cable insulation materials

DC resistivity and AC breakdown strength of flexible polypropylene (trade marked name Hifax) cable insulation materials have been measured at selected temperatures. The AC breakdown data has been analysed in terms of Weibull distribution. The results show that Hifax cable insulation has a higher AC breakdown strength than EPR (ethylene propylene rubber) and XLPE (crosslinked polyethylene), both of which are widely used for DC cable insulation. It is concluded that blending Hifax with ordinary polypropylene decreases the breakdown strength. The DC resistivity of Hifax is larger than that of XLPE and oil-impregnated paper insulations. It has been found that the electrical stress coefficient of resistivity of Hifax cable insulation increases with temperature, which may have important engineering implications. An anomalous drop in resistivity has been observed for Hifax at high electrical fields, suggesting charge trapping and detrapping processes are present in these cable insulations.     

LED有机硅封装材料的研究进展

有机硅封装材料具有较好的绝缘性能、耐候性能、耐紫外线性能及较高的透光率和折射率等,其固化时应力较小,不易发生黄变,可有效延长LED的使用寿命,是较为理想的LED封装材料。综述了有机硅改性环氧树脂类封装材料和有机硅类封装材料的研究进展,并展望了其未来的研究方向。     

Development of bridge tooling for fabricating mold inserts of aspheric optical lens

A bridge tooling is developed for fabricating the temporary mold inserts of aspheric lens using silicone rubber materials. Prototype material of the aspheric lens is not recommended as quartz due to low successful rate in the fabrication process. This technology provides a fast, low cost, and high successful rate for fabricating the epoxy‐based composites mold inserts of plastic aspheric optical lens.     

Testing of the fire-proof functionality of cable insulation under fire conditions via insulation resistance measurements

Two different designs for low-fire-hazard cables were tested under conditions similar to those of the fire test specified in IEC 60331-21. In addition to the other standard requirements, an insulation resistance meter was connected directly to the measurement circuit to monitor the actual state of the cable insulation during the fire tests. The suitability of this measurement of the insulation resistance was demonstrated by testing cables with fire barriers made from mica glass tape and from ceramifiable silicone rubber. The results showed that insulation resistance is sensitively affected by the melting of the organic components of insulation, by the decomposition of the fire retardant, by the ignition of the core insulation and by the formation of a silica layer during a fire test. The results also helped to reveal the importance of flame conductivity in performing such tests. The initial observations are supported by thermogravimetry and differential scanning calorimetry, which are beneficial as a first step towards understanding the mechanisms of fire-proof functionality in cables. The suggested procedure can assist in the comparison of the fire-proof functionalities of different cable designs, in the analysis of their failure mechanisms and in cable design optimisation.     

Manufacture and mechanical characterisation of high voltage insulation for superconducting busbars – (Part 1) Materials selection and development

It is planned that the high voltage electrical insulation on the ITER feeder busbars will consist of interleaved layers of epoxy resin pre-impregnated glass tapes (‘pre-preg’) and polyimide. In addition to its electrical insulation function, the busbar insulation must have adequate mechanical properties to sustain the loads imposed on it during ITER magnet operation. This paper reports an investigation into suitable materials to manufacture the high voltage insulation for the ITER superconducting busbars and pipework. An R&D programme was undertaken in order to identify suitable pre-preg and polyimide materials from a range of suppliers. Pre-preg materials were obtained from 3 suppliers and used with Kapton HN, to make mouldings using the desired insulation architecture. Two main processing routes for pre-pregs have been investigated, namely vacuum bag processing (out of autoclave processing) and processing using a material with a high coefficient of thermal expansion (silicone rubber), to apply the compaction pressure on the insulation. Insulation should have adequate mechanical properties to cope with the stresses induced by the operating environment and a low void content necessary in a high voltage application. The quality of the mouldings was assessed by mechanical testing at 77 K and by the measurement of the void content.     

Preparation and properties of hollow glass bead filled silicone rubber foams with low thermal conductivity

Silicone rubber foams filled with various content and different particle size of hollow glass bead (HGB) were prepared by compression molding. It was revealed that compared with silica filled silicone rubber foams, HGB filled materials achieved higher foaming extent, lower thermal conductivity, and lower hardness, which can be significant for thermal insulation materials. For HGB filled materials, the morphology indicated the average cell size decreased with higher HGB content and larger particle size of HGB. The density, thermal conductivity, hardness and tensile strength increased with higher HGB content and larger particle size of HGB.