填料对双组分缩合型室温硫化硅橡胶性能的影响

考察了多种补强填料和半补强(或增量)填料如硅藻土、碳酸钙和氧化铝等对室温硫化(RTV)硅橡胶的机械性能和介电性能的影响。结果表明,采用经六甲基二硅氮烷处理的气相法白炭黑或沉淀法白炭黑作填料时,RTV硅橡胶多方面的性能都有所提高;采用补强填料和半补强填料并用的RTV硅橡胶的性能优于使用单一补强填料的RTV硅橡胶;随着填料用量的增加,RTV硅橡胶的机械性能、相对介电常数和介质损耗因数都有一定程度的提高,但体积电阻率有所降低。     

Monomer recycling for vulcanized silicone rubbers in the form of cyclosiloxane monomers. Role of acid buffers

The KOH-catalyzed depolymerization of vulcanized silicone rubbers to reproduce cyclosiloxane monomers was studied. First, the depolymerization was carried out in toluene with varying amounts of KOH to find that the yield of monomers first increased and then decreased with the increment of KOH, the highest yield was 65% at the molar ratio KOH/(Si–O) UNITS=0.08. At the molar ratio 0.13 in the absence of solvent, the monomers yield was 46%. However, when an acid buffer such as KH₂PO₄ and KCOOC₆H₄COOH was added after the KOH-catalyzed depolymerization was over, the product yield was increased remarkably to more than 80%.     

Effect of surface chemistry and morphology of silica on the thermal and mechanical properties of silicone elastomers

In this study, high‐temperature vulcanized silicone rubbers (HTV‐SRs) using fumed silica (FSi), precipitated silica (PSi), and modified precipitated silica (MPSi) as reinforcing fillers were prepared. The effect of morphology and surface chemistry of the silica on the thermal and mechanical properties of the resultant silicone rubbers was investigated using curing rheometer, scanning electron microscopy, mechanical test, and dynamic mechanical analysis. The thermo‐oxidative stability and solvent resistance of the vulcanized silicone rubbers were further evaluated via heat ageing test, extraction, and swelling experiments. It is shown that the mechanical properties (tensile modulus and tensile strength) of the as‐prepared HTV‐SRs are in the order of FSi > PSi > MPSi, which could be attributed to the molecular interaction between the filler and the matrix. FSi has the highest surface area, which enhances the hydrogen bonding interaction between the filler and the silicone matrix; while MPSi, in which part of Si? OH groups have been consumed during modification, shows the weakest interaction among the three. The filler–matrix interaction could also explain the lowest swelling and sol fraction in FSi‐filled HTV‐SR, and the low viscosity and good processibility of PSi‐ and MPSi‐filled HTV‐SR. Furthermore, it is also shown that the MPSi‐filled HTV‐SR exhibits the highest retention of mechanical properties after thermal aging at 250 °C for 24 h, which could be attributed to the lowest acidity of the fillers. The possible mechanism for acid catalyzed hydrolytic chain scission and intramolecular chain backbiting has been proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46646.     

热硫化硅橡胶废胶裂解回收环体的再利用

采用碱催化法裂解热硫化硅橡胶生胶生产中的废胶并对裂解料进行二次精馏，去除高、低沸物杂质，使回收的混合环体可再次用于合成热硫化硅橡胶。     

硅橡胶隔热复合材料的制备及性能

采用空心玻璃微珠（HGB）和膨胀蛭石（EVMT）作为隔热填料,分别与高温硫化硅橡胶（HTV）共混制备HGB/HTV和EVMT/HTV隔热复合材料,并考察了隔热填料的种类和用量对隔热复合材料的隔热性能和力学性能的影响。结果表明,随着HGB和EVMT用量的增加,隔热复合材料的导热性能明显下降。相比于HTV试样,当HGB与HTV的质量比为20/100,EVMT与HTV的质量比为10/100时,隔热复合材料的导热系数分别下降了20.44%和12.34%。HGB和EVMT均能提高HTV隔热复合材料的100%定伸应力和邵尔A硬度,降低其拉伸强度与扯断伸长率。当HGB与HTV的质量比为20/100,EVMT与HTV的质量比为10/100时,隔热复合材料的拉伸强度分别为10.51 MPa和11.59 MPa,邵尔A硬度分别为71.6和59.1。     

影响HTV硅橡胶撕裂强度的因素

考察了白炭黑种类、羟基硅油用量、含氢硅油用量以及不同乙烯基含量生胶并用对热硫化(HTV)硅橡胶撕裂强度的影响。结果显示,气相法白炭黑的补强效果强于沉淀法白炭黑,且比表面积越大,硅橡胶的撕裂强度越高;随着羟基硅油加入量的增加,硅橡胶的撕裂强度先增后趋于稳定;含氢硅油的用量对HTV硅橡胶的撕裂强度基本没有影响;高乙烯基含量生胶和低乙烯基含量生胶并用能显著提高HTV硅橡胶的撕裂强度。较佳配方是:166 g 110-0生胶,4 g 112生胶、80 g QS-102气相法白炭黑、8.5 g羟基硅油、1.0 g含氢硅油、0.5 g乙烯基硅油,此时,HTV硅橡胶的撕裂强度达到21 KN/m。     

导热填料对室温硫化硅橡胶性能的影响

分析比较了氮化硅、氧化锌、勃姆石、氮化铝、碳化硅和石英粉等6种填料对室温硫化硅橡胶性能的影响,优选出氮化硅作为导热填料。比较了不同粒径的氮化硅性能,制备了综合性能较好的导热室温硫化硅橡胶。     

高温硫化硅橡胶改性及老化研究进展

高温硫化硅橡胶由于其优异的高低温性能、耐候性、表面性能等特点而在航天、电力和医疗器械等领域中得到广泛应用。本文主要介绍了最近五年来,通过化学或物理方法对硅橡胶表面性能和低温性能等进行强化方面的相关研究,以及在实现产品功能化方面取得的进展。此外还介绍了在加速老化条件下不同硅橡胶材料的力学、介电性能等变化及其机理,以及在老化研究方法的精确化、可靠化和可视化方面的研究进展,重点关注多因素影响下的材料寿命分析和预测;并特别关注了水在硅橡胶老化过程中的作用及机理研究成果。最后,对高温硫化硅橡胶改性和老化研究的前景进行了展望。未来,极端环境下的硅橡胶功能化研究以及多因素影响下的材料寿命分析和预测将成为重要的发展方向。     

粉状填充剂对橡胶复合材料拉断伸长率的影响

以不同粒径的氢氧化镁、轻质碳酸钙和炭黑N110填充SBR、EPDM、NBR和硅橡胶，探讨粉状填充剂（简称粉体）对其填充橡胶复合材料拉断伸长率的影响。结果表明，粉体的表面活性、粒径、分散性、用量以及基体橡胶的拉伸强度和拉断伸长率等因素对橡胶复合材料拉断伸长率的影响存在着竞争关系。粉体的粒径和基体橡胶的交联密度影响橡胶复合材料拉断伸长率随粉体用量增大而提高的幅度。粉体对基体橡胶表现出较强的补强作用时，使橡胶复合材料的拉断伸长率出现峰值的粉体用量较小。与传统观点不同，试验得出大多数情况下填充粉体有利于橡胶复合材料拉断伸长率提高的结论。     

耐热型热硫化混炼胶的研制

以甲基乙烯基硅橡胶为生胶,添加气相法白炭黑、耐热添加剂等制得耐热型热硫化硅橡胶,研究了生胶中羟基含量、白炭黑种类、白炭黑处理剂种类以及耐热剂种类对硅橡胶耐热性能的影响。结果表明,当采用羟基质量分数≤15×10^-6、乙烯基摩尔分数为0.19%的甲基乙烯基硅橡胶生胶时,其抗降解表现更好;不同类型白炭黑在不同的老化温度下对硅橡胶的影响不同,225℃及以下温度条件下,亲水型白炭黑的耐热效果优于疏水型白炭黑,225~300℃及以上温度条件下,疏水型白炭黑更优;在白炭黑处理剂对硅橡胶耐老化影响方面,采用聚二甲基二苯基硅氧烷RP140PH比常规低黏度羟基硅油和六甲基二硅氮烷更好;耐热剂对硅橡胶体系耐老化效果提升极为明显,其提升效果由高到低依次为AD105、AD111、AD104、AD110。     

硅橡胶在电力行业中的应用及前景

介绍了硅橡胶（热硫化硅橡胶、室温硫化硅橡胶、液态硅橡胶）的性能及在电力行业中的应用,展望了硅橡胶在电力行业的应用前景。     

硅橡胶在电力系统外绝缘中的应用

通过试验数据分别分析了在输变电设备上使用的室温硫化硅橡胶和热硫化硅橡胶（HTV）的运行特性，着重介绍了运行条件对HTV硅橡胶憎水性能的影响、运行HTV硅橡胶的耐漏电起痕及电蚀损性能、机械性能和积污特性。认为因老化引起的憎水性、机械强度、积污性能下降以及材料劣化均影响着其长期工作的可靠性，需改进配方，以满足外绝缘材料长期运行的要求；并比较了3种硅橡胶材料的老化试验方法：斜面法、1000h盐雾法及5000h老化试验方法的试验条件、试验程序、试验现象、试验结果和试验评定的差异。     

Cold plasma modification of boron nitride fillers and its effect on the thermal conductivity of silicone rubber/boron nitride composites

Hexagonal boron nitride (h‐BN) fillers were first coated with low‐molecular‐weight polydimethylsiloxane (PDMS) by solution dispersion and then treated in argon plasma for different times. The modified h‐BN fillers were characterized by high‐resolution transmission electron microscopy, X‐ray photoelectron spectroscopy, and contact angle analysis. The results revealed that a thin PDMS film several nanometers thick was tightly coated on the surface of the h‐BN filler after plasma treatment, and this thin film could not be removed by 48 h Soxhlet extraction with n‐hexane at 120°C. Furthermore, the effect of plasma modification on the h‐BN filled silicone rubber composites was investigated. The results indicated that the plasma modification improved the interfacial interaction between h‐BN and the matrix, but hardly affected the distribution state of the h‐BN in the composites. The composites filled with the modified h‐BN exhibit significantly higher thermal conductivity than the composites filled with untreated h‐BN. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

UV-Ozone Surface Treatment of SBS Rubbers Containing Fillers: Influence of the Filler Nature on the Extent of Surface Modification and Adhesion

SBS rubbers containing different loadings of calcium carbonate and/or silica fillers were surface treated with UV-ozone to improve their adhesion to polyurethane adhesive. The surface modifications produced on the treated filled SBS rubbers have been analyzed by contact angle measurements, ATR-IR spectroscopy, XPS and SEM. The adhesion properties have been evaluated by T-peel strength tests on treated filled SBS rubber/polyurethane adhesive/leather joints. The UV-ozone treatment improved the wettability of all rubber surfaces, and chemical (oxidation) and morphological modifications (roughness, ablation, surface melting) were produced. The increase in the time of UV-ozone treatment to 30 min led to surface cleaning (removal of silicon-based moieties) due to ablation and/or melting of rubber layers and also incorporation of more oxidized moieties was produced. Although chemical modifications were produced earlier in an unfilled rubber for short time of treatment with UV-ozone, they were more noticeable in filled rubbers for extended length of treatment, mainly for S6S and S6T rubbers containing silica filler. The oxidation process seemed to be inhibited for S6C and S6T rubbers (containing calcium carbonate filler). On the other hand, the S6S rubber containing silica filler and the lowest filler loading showed the higher extent of modification as a consequence of the UV-ozone treatment. The UV-ozone increased the joint strength in all joints, more noticeably in the rubbers containing silica filler, in agreement with the greater extents of chemical and morphological modifications produced by the treatment in these rubbers. Finally, the nature and content of fillers determined the extent of surface modification and adhesion of SBS rubber treated with UV-ozone.     

Molecular design of damping rubber based on polyacrylate‐containing silicone

A series of damping rubbers based on poly(meth)acrylate and poly(meth)acrylate‐containing silicone rubbers has been prepared. The dynamical mechanical properties were evaluated by using a dynamic mechanical viscoelastometer (DMA). A detailed investigation is reported on the relationship of the damping capability of the poly(meth)acrylate rubbers with their composition and macromolecular architecture. Also discussed is the effect of two kinds of silicone elastomers on the damping performance of the polyacrylate‐containing silicone rubber. The results indicate that, in vulcanized rubber systems, both statistical copolymerization for multiple monomers and blending between immiscible polymers with close T_gs facilitate broadening the glass transition peaks. Furthermore, the molecular design is quite an effective approach in which the multiple monomers whose polymers have a ladder‐changing T_g are used to synthesize the damping rubber with the broad effective functional area. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 746–751, 2002     

甲基乙烯基硅橡胶并用体系研究

并用两种乙烯基含量不同的甲基乙烯基硅橡胶，添加适量含氢硅油，同时采用过氧化物和铂催化加成这两种硫化方式。可以得到高撕裂乙烯基硅橡胶。结果表明，当乙烯基质量分数为0．09％和0．13％的生胶并用比为50／50时，其撕裂强度比单独使用两种生胶时分别提高了46．9％和21．7％；两种硫化体系并用时，性能有了显著提高，超过了单独使用一种硫化方式的性能。     

有机硅裂解生产装置改造

介绍了以溶剂油为载热体的甲基氯硅烷水解物裂解技术原理、工艺流程、产业化过程和效果.通过用溶剂油为载热体进行水解物裂解及混合环硅氧烷精馏,生产出聚合物中间体八甲基环四硅氧烷(D4),该产品用于合成高温硫化硅橡胶、室温硫化硅橡胶、硅油等.     

有机硅在绝缘子防污闪方面的应用

简述了硅油、硅脂、室温硫化硅橡胶、高温硫化硅橡胶、硅树脂等有机硅材料在绝缘子防污闪方面的应用     

Solid‐state microcellular high temperature vulcanized (HTV) silicone rubber foam with carbon dioxide

A series of microcellular high temperature vulcanized (HTV) silicone rubber foams were prepared using CO₂ as a physical blowing agent. Rheological properties, gas diffusive behavior, and foaming parameters of silicone rubber were investigated. The results show that saturation pressure has a significant effect on the diffusivity of CO₂ in HTV silicone rubber matrix. The gas concentration and diffusivity increase from 2.45 wt % to 3.24 wt %, and from 1.62 × 10^?5 cm²/s to 7.83 × 10^?5 cm²/s as the saturation pressure increases from 2 MPa to 5 MPa, respectively. The value of the gas diffusivity in HTV silicone rubber is almost 1000 times higher than that of the gas diffusivity in polyetherimide (PEI) matrix. Additionally, microcellular HTV silicone rubber foams with the smallest cell diameter of 9.8 μm and cell density exceeding 10⁸ cells/cm³ are achieved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44807.     

加成型高温硫化液体硅橡胶的气泡消除及性能研究

研究了交联剂、催化剂和消泡剂等对加成型高温硫化(HTV)液体硅橡胶气泡消除及性能的影响。结果表明：随着交联剂与催化剂用量增加,硅橡胶的固化时间变短,产生气泡增多;使用消泡剂可有效抑制硅橡胶中气泡的产生。当交联剂用量为0.95phr、催化剂用量为1.05phr、消泡剂4用量为4‰时,加成型HTV液体硅橡胶的综合性能最佳。