Hydrophilicity Modification of Addition-cured Room Temperature Vulcanization Silicone Rubber

Allyl terminated polyether was used to improve the hydrophilicity of addition-cured room temperature vulcanization silicone rubber. With the increasing of the polyether, both the hydrophilicity and water absorbed of the vulcanizates were increased. The mechanical properties were also improved by adding the polyether. The result showed that 1.5wt% of the polyether provided the silicone rubber with proper hydrophilicity.

STUDIES ON SELF-VULCANIZING FLUOROELASTOMER/PHENOL HYDROXY SILICONE RUBBER BLENDS

Self-vulcanizing blends of phenol hydroxy silicone rubber (PHSR) and fluoroelastomer (FPM) were prepared. Vulcanized rubbers with lower glass transition temperature (T(g)) were successfully obtained. The results of dynamic mechanical analysis (DMA) show that the vulcanized FPM/PHSR (10 phr) blend has only one T(g) temperature, demonstrating the well compatibility between FPM and PHSR. The thermogravimetric analysis (TGA) demonstrates that the PHSR do little damage to the thermal stability of FPM. The vulcanization characteristics of the FPM/PHSR blends were analyzed by using oscillating disc rheometer (ODR). The results show that FPM/PHSR blends have smaller S(min) values and longer scorch time than that of FPM with the same level of bisphenol AF curing agent. It means that FPM/PHSR blends have better processability and curing security. Better mechanical properties can be gained for FPM/PHSR blends at appropriate level of PHSR.

Use of Shore Hardness Tests for In-Process Properties Estimation/Monitoring of Silicone Rubbers

Casting is an important rubber manufacturing process for both production and material developments. A quick and flexible way of testing the constitutive materials properties of rubber products is very important for optimising the processing parameters and quality control. In many cases, standard tests such as tensile or compression tests are time consuming and require a large volume of materials. This work reports some recent work in using a combined numerical and experimental approach to characterise the properties of rubber materials during a casting process. Durometer shore hardness is used to test silicone rubbers (as a model material) with different compositions on different moulding planes and the linear elastic property is estimated from the hardnesses. The predicted properties are systematically compared with the experimental tests on hard and soft silicone rubber samples with different compositions. The work shows that shore hardness can be used as an effective way to monitor the materials properties during amoulding process for process optimisation and quality control.

Improving the Thermal Conductivity and Mechanical Properties of Twocomponent Room Temperature Vulcanized Silicone Rubber by Filling with Hydrophobically Modified SiO_2-Graphene Nanohybrids

The SiO_2 nanoparticles were coated on the surface of graphene oxide(GO) by sol-gel method to get the SiO_2-G compound.The SiO_2-G was restored and oleophylically modified to prepare hydrophobic modified SiO_2-G(HM-SiO_2-G) which was subsequently added to silicone rubber matrix to prepare two-component room temperature vulcanized(RTV-2) thermal conductive silicone rubber. The morphology, chemical structure and dispersity of the modified graphene were characterized with SEM, FTIR, Raman, and XPS methods.In addition, the heat-resistance behavior, mechanical properties, thermal conductivity, and electrical conductivity of the RTV-2 silicone rubber were also studied systematically. The results showed that the SiO_2 nanoparticles were coated on graphene oxide successfully, and HM-SiO_2-G was uniformly dispersed in RTV-2 silicone rubber. The addition of HM-SiO_2-G could effectively improve the thermal stability, mechanical properties and thermal conductivity of RTV-2 silicone rubber and had no great influence on the electrical insulation performance.

Effect of UV radiation aging on creepage discharge characteristics of high temperature vulcanized silicon rubber at high altitude

The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this study.The experimental results show that as the aging time increases,the creepage discharge flashover voltage increases first and then decreases.But the aging time has little effect on the creepage discharge inception voltage.With the aging time prolonged,the discharge endurance time of HTV silicone rubber is shortened,and the creepage discharge development velocity is accelerated.In the short time of applying voltage to aging material,the magnitude of discharge in creases rapidly.According to the partial discharge characteristic parameters of creepage discharge,the whole creepage discharge process is partitioned into four stages.Compared with unaged HTV silicone rubber,the aged HTV silicone rubber has less fluctuation in performance parameters and a clear trend.The study found that UV aging not only affects the physicochemical and hydrophobic properties of the HTV silicone rubber,but also accelerates the development of creepage discharge under AC voltage.

耐高温单组分室温硫化硅橡胶的研制

以自制的不同类型的单组分室温硫化硅橡胶为基础,考察了脱酸型、脱醇型、脱肟型、脱丙酮型硅橡胶在高温老化条件下的性能变化。结果表明,脱丙酮型硅橡胶在高温老化后,其力学性能最好,拉伸强度和断裂伸长率保持率最高。因此在脱丙酮型硅橡胶基础上,考察生胶黏度及结构、白炭黑、耐热助剂等对单组分脱丙酮型室温硫化硅橡胶耐高温性能的影响。结果表明:单组分脱丙酮型室温硫化硅橡胶在200℃高温老化时,主要是侧链发生氧化反应;在300℃高温老化时,主要发生的是主链降解反应。低黏度生胶和侧基为低含量的苯基时,对硅橡胶耐高温性能有利;采用硅氮烷处理的气相法白炭黑作为补强填料时,硅橡胶耐高温性能较好;氧化铁红、氧化铈、氧化钛对硅橡胶耐高温性有小幅度的提高,而二氧化钛与氧化铁红复配使用时,因其协同作用,大幅度提高了硅橡胶的耐高温性能。在300℃×2 h老化后,硅橡胶的拉伸强度和断裂伸长率都保持在90%以上。

双组分缩合型透明灌封胶的制备及性能研究

将α,ω-二羟基聚二甲基硅氧烷、二甲基硅油、含氢硅油混合制得A组分,以二甲基硅油为主体,与交联剂、硅烷偶联剂、催化剂混合制得B组分;A、B组分按10∶1混合制得深层固化性能优异的双组分缩合型室温硫化(RTV-2)硅橡胶。研究了活性氢质量分数不同的含氢硅油及其用量对RTV-2硅橡胶性能的影响。结果表明,优选活性氢质量分数为0.36%的侧含氢硅油,且当添加量为3 g时,制得的硅橡胶综合性能最佳,能够满足LED照明灯具密封防水及粘接需求。

含氢硅油对氟硅密封剂性能影响

研究了不同种类的含氢硅油对脱氢型氟硅密封剂力学性能、耐介质性能及耐热性能的影响。结果表明,甲基含氢硅油作交联剂时密封剂力学性能较好,随着活性氢质量分数的增加,拉伸强度和硬度上升,断裂伸长率下降;采用含氢氟硅油作交联剂时,密封剂的耐介质性能相对最好;苯基含氢硅油作交联剂时,氟硅密封剂的耐热性能相对最好。

模拟运行环境状态下动车组绝缘子剩余寿命研究

本文提出了一种关于复合绝缘子高温硫化硅橡胶在综合老化作用下的使用寿命和剩余寿命的分析方法。通过分析新品绝缘子硅橡胶在综合老化试验中拉伸强度的退变趋势和五级修硅橡胶的初始拉伸强度,评估其新品硅橡胶使用寿命和五级修硅橡胶的剩余寿命。实验表明,新品硅橡胶在综合老化条件下退变到五级修的加速因子为18.64;进一步评估新品伞裙的使用寿命为14.8年,五级修绝缘子伞裙的剩余寿命为6.8年。后续可为绝缘子的检修策略优化提供数据支撑。

DTQ硅树脂的制备及对RTV-2硅橡胶性能的影响

采用二甲基二甲氧基硅烷、甲基三甲氧基硅烷、正硅酸乙酯经水解缩聚制得DTQ硅树脂,将其添加到双组分室温硫化(RTV-2)硅橡胶中。研究了DTQ硅树脂用量、T链节含量、Q链节含量、烷氧基水解程度对RTV-2硅橡胶性能的影响。结果表明,DTQ硅树脂含有较多的活性羟基,加入RTV-2硅橡胶后能在催化剂作用下优先与α,ω-二羟基聚二甲基硅氧烷反应,提高聚二甲基硅氧烷的分子量并增加支链结构,进而提升RTV-2硅橡胶的断裂伸长率;制备DTQ硅树脂的较佳条件为二甲基二甲氧基硅烷、甲基三甲氧基硅烷、正硅酸乙酯物质的量之比为1∶0.2∶0.2,水添加量为体系中烷氧基物质的量的50%;DTQ硅树脂的较佳用量为6%,此时制得的RTV-2硅橡胶断裂伸长率为338%,拉伸强度保持在0.97 MPa,拉断时间保持30 min以上。

三聚氰胺聚磷酸盐(MPP)对高温硫化硅橡胶的阻燃和陶瓷化性能的影响

为协同提升高温硫化硅橡胶的阻燃与陶瓷化性能,以高温硫化硅橡胶为基体,结合煅烧高岭土、磷酸盐玻璃粉和三聚氰胺聚磷酸盐(MPP)制备了阻燃可陶瓷化硅橡胶复合材料。采用垂直燃烧仪、锥形量热仪(CONE)、热重分析仪(TGA)、傅里叶红外光谱仪(FTIR)、扫描电子显微镜(SEM),研究了MPP的组分占比以及硅氧烷粉体改性对硅橡胶复合材料燃烧性能和陶瓷化性能的影响。结果表明:MPP的添加能够有效降低复合材料的热危害,同时提高复合材料煅烧后得到的类陶瓷体的强度;当MPP在15 wt%的组分占比下,1000℃煅烧后样品的弯曲强度超过15 MPa,通过粉体改性可以使MPP恶化的力学强度得到恢复。

低模量脱醇型室温硫化硅橡胶的研制

以α,ω-二羟基聚二甲基硅氧烷为基础聚合物,纳米碳酸钙为补强填料,二甲基硅油、MDT硅油为增塑剂,甲基三甲氧基硅烷为交联剂,甲基乙烯基二甲氧基硅烷为扩链剂,添加催化剂、粘接促进剂等制得脱醇型单组分室温硫化硅橡胶。研究了纳米碳酸钙种类、增塑剂组分及用量、扩链剂用量对硅橡胶性能的影响。结果表明,补强填料选择以脂肪酸和硅烷偶联剂复配物作表面处理剂的纳米碳酸钙较佳;单独以二甲基硅油作增塑剂时,随着二甲基硅油用量由0增加到40份,硅橡胶的拉伸强度由1.67 MPa降至0.92 MPa,拉断伸长率由523%升至807%,拉伸模量由0.72 MPa降至0.32 MPa。二甲基硅油的较佳用量为20份;以MDT硅油与二甲基硅油复配物作增塑剂、增塑剂总用量固定为20份的条件下,随着MDT硅油质量比的升高,硅橡胶的拉伸强度和拉伸模量先降后升,拉断伸长率先升后降,挤出性逐渐降低。增塑剂采用10份MDT硅油与10份二甲基硅油复配较佳;向体系中加入扩链剂并不断提高用量,硅橡胶的表干时间延长,拉伸模量降低,拉断伸长率先升后降。扩链剂的较佳用量为1份;在上述优选条件下制得的硅橡胶综合性能较佳,拉伸模量为0.26 MPa,拉断伸长率为876%,表干时间为50 min,可作为低模量有机硅密封胶用于道路嵌缝填缝和保温装饰一体化板填缝密封等领域。

MWCNTs增强硅橡胶耐烧蚀特性研究

多壁碳纳米管(MWCNTs)凭借优异的物理化学性能,可被用作补强填料来改善复合材料的性能。目前对MWCNTs改善室温硫化(RTV)硅橡胶材料耐烧蚀性能的机理还没有较深入的研究。为了研究MWCNTs对RTV硅橡胶耐烧蚀性能的影响,采用溶液共混法制备了不同配方的MWCNTs/RTV硅橡胶复合材料。通过氧乙炔烧蚀试验,结合扫描电子显微镜(SEM)研究其烧蚀特性,分析碳化层的微观形貌,从碳化层结构、孔隙率、热解气体沉积等方面方面揭示了碳纳米管改善RTV硅橡胶复合材料耐烧蚀性能的内在机理。结果表明:MWCNTs对RTV硅橡胶耐烧蚀性能有增强作用,在添加量为1份时线烧蚀率最低为0.133 mm/s,碳化烧蚀率最低为0.186 mm/s,比未添加MWCNTs的材料分别降低21.5%、12.8%。通过SEM分析碳化层微观形貌发现,碳化层表面一侧形成较厚的致密层,背面一侧孔隙率较大,在碳化层中观测到相互交错联结的MWCNTs,其表面有较多热解产物沉积。MWCNTs的添加增加了碳化层结构强度,促进了致密层的形成,有效提高了RTV硅橡胶的耐烧蚀性能。

低密度阻燃室温硫化硅橡胶的研制

以端羟基聚二甲基硅氧烷为基体,采用空心玻璃微珠、三聚氰胺氰尿酸盐、氢氧化铝等作填料,制备了单组分低密度阻燃室温硫化硅橡胶。考察了氢氧化铝、三聚氰胺氰尿酸盐及两者的复配物对硅橡胶力学性能和阻燃性能的影响。表征了空心玻璃微珠的微观结构及其在阻燃硅橡胶基体中的分散情况,并探讨了空心玻璃微珠对硅橡胶密度和力学性能的影响。结果表明:当硅橡胶达到FV-0级阻燃时,单纯使用氢氧化铝需要添加110份,三聚氰胺氰尿酸盐需要添加125份,而两者复配时,仅需添加90份即可使硅橡胶达到FV-0级阻燃水平。在阻燃硅橡胶体系中加入空心玻璃微珠,其在基体中能均匀分散,且随着其用量的增加,密度和断裂伸长率呈现降低趋势;综合考虑性能和密度等因素后,玻璃微珠较佳质量分数为20%。

室温硫化发泡硅橡胶研究进展

室温硫化发泡硅橡胶兼具硅橡胶和泡沫材料的优点,在越来越多的领域中展现出巨大潜力,受到国内外研究者重点关注。本文介绍了近年来有关室温硫化发泡硅橡胶的相关研究。首先介绍了基础组分和补强填料对发泡硅橡胶性能影响的相关研究。然后对功能性发泡硅橡胶的研究进展进行了总结,包括阻燃防火材料、吸声材料、包装材料、导热材料和热化学储能材料等。最后对室温硫化发泡硅橡胶未来发展方向进行了展望。

有机硅材料的UV固化反应机理研究及发展

汽车底盘系统使用的有机硅材料通常为脱醇型单组分室温硫化(RTV)有机硅密封胶和双组分加成型有机硅基热界面材料。介绍了脱醇型单组分有机硅密封胶的RTV和紫外光(UV)固化反应机理,以及双组分加成型有机硅基热界面材料的传统固化和UV固化反应机理,指出使UV固化型有机硅密封胶、有机硅基热界面材料产品达到传统固化产品的性能是今后研发的重点。

硫化橡胶与金属的室温黏合研究

本文以环氧树脂作为硫化丁腈橡胶与金属的室温黏合,在硫化橡胶表面引入chemlok固化过度层,实现橡胶与金属在室温下的高强度黏合,对影响黏合强度的各种因素进行研究,确定了最优的硫化橡胶表面处理方式、过度层组分、过渡层固化条件。研究结果表明对硫化橡胶进行打磨可获得更高的黏合强度,采用chemlok205底涂和chemlok220面涂的双涂层黏合性能最优,过镀层在140℃下固化。随着固化时间的增加,黏合强度随之增加,在40 min后趋于稳定,黏合剂固化时间以24 h为宜。

一种风冷式SVG装置性能提升方法及实际应用

目前采用的无功补偿绝大多数是投切固定容量的电容器组,只有少量同步调相机和静止无功补偿器,可调节的无功容量不足,能快速响应的无功调节设备就更少。而SVG技术日趋成熟在电力系统无功补偿方面正发挥着越来越重要的作用。早期投用的一些SVG设备主要是靠风冷方式进行冷却,在设计中又诸多不合理之处,造成设备故障频发,鉴于上述原因,需要对设备继续一些列技改以提高设备的性能,满足电力生产的实际需求。

运行多年RTV涂料绝缘子表面涂层老化分析研究

室温硫化硅橡胶涂料(RTV涂料)可以有效防止污闪事故,已在我国电力系统中广泛应用。文中通过取得大量在天津挂网运行多年老化的RTV涂料绝缘子,在对其表面憎水性和积污状况研究的基础上,进行了两种状态下试品防污闪能力测试,结果表明试品仍具有良好的防污闪能力。通过绝缘子试品表面涂层的红外分析对比,讨论了线路周边污染源环境对RTV涂层的不同影响。针对RTV涂料国内比较保守的寿命定义,通过热重分析,引入胶含量的概念,结合防污闪性能及红外谱图的变化,提出了对RTV涂料寿命评估新的参考方法,并对RTV涂料在不同运行条件下的实际使用寿命给出了指导性意见。

室温硫化硅橡胶涂层憎水性迁移机理的研究

研究了环境温度、硅橡胶的分子量、交联程度和涂层厚度等因素对憎水迁移特性的影响并对憎水性迁移机理问题进行了讨论。对目前较为流行的小分子硅氧烷迁移机理的假说进行了实验验证，气相色谱、裂解色谱以及红外谱图的分析结果不支持小分子硅氧烷迁移机理的假说。