微纳粒子/纤维增强耐高温加成型导热硅橡胶的研究

将纳米尺寸乙烯基甲基MQ硅树脂、硼酸酯偶联剂、微米级导热BN填料混杂在端乙烯基甲基硅油中,通过交联剂含氢甲基硅油、抑制剂乙炔基环己醇及Karstedt催化剂制备出具有室温流动性好、操作时间长的液体硅橡胶,探讨了体系的热交联固化增强机理。通过玻璃纤维改性的硅橡胶的拉伸强度可提高1倍以上。随着BN掺量的增加,导热率大幅提升,导热率可达到1.9 W/(m·K),并且具有较高的耐高温性能,此时10%的质量损失时的温度可达658 K。     

耐高温高导热硅橡胶的研究与应用进展

概述了导热硅橡胶的种类、组成、固化机理和应用及发展方向。分析了硅橡胶的热老化机理,概述了几种提高硅橡胶耐热老化性能的方法,指出添加含杂原子聚硅氧烷是提高硅橡胶耐热性和综合性能的一条非常重要的有效途径。同时系统阐述了导热硅橡胶的导热理论和机理及提高硅橡胶导热性的方法,概述了导热填料的种类、晶体结构、粒径及制法、取向和纤维化及表面处理和复合杂化对硅橡胶导热性能的影响。     

c-BN对绝缘高导热硅橡胶性能的影响

采用聚二甲基硅氧烷基础胶、含氢硅油交联剂、立方氮化硼(c-BN)导热填料,制备了绝缘高导热硅橡胶;研究了c-BN的不同含量对硅橡胶导热性能、绝缘性能、物理性能的影响。结果表明:填充改性c-BN粉体可以大幅度提高硅橡胶体系的导热性能,在c-BN用量为80%时导热系数为7.16 W/(m·k),热阻为3.39 cm~2K/W;c-BN粉体会降低硅橡胶体系的绝缘性能和力学弹性,但当用量不超过80%时,击穿强度大于6 k V/mm、体积电阻率大于1×1012Ω·cm、硬度小于55、压缩永久变形小于30%,符合实际使用中的绝缘需要,符合产品安装和使用的条件,不易被压碎、压裂而且具有一定弹性。     

聚氯乙烯表皮成分对加成型硅橡胶固化的影响

采用流变学方法研究了双组分加成型硅橡胶在不同聚氯乙烯(PVC)表皮上的固化动力学,并利用红外光谱、核磁共振波谱、电感耦合等离子体质谱仪等手段分析了PVC表皮成分,以确定导致双组分加成型硅橡胶不固化的具体原因。 结果表明,PVC表皮中导致硅橡胶不固化的主要元素为P元素。 在固定硅橡胶厚度为1 mm的情况下,当PVC表皮中的P元素质量分数低于3×10^-3%时,浇注在其上的双组分加成型硅橡胶依然能固化;而当PVC表皮中的P元素质量分数超过约2.4×10^-2%时,虽然浇注在其上的双组分加成型硅橡胶的中间层依然能固化,但与PVC表皮接触部分的硅橡胶不固化,且不固化层厚度随P元素质量分数增加而增加。 本文还研究了在P元素质量分数低于3×10^-3%的PVC表皮上,降低硅橡胶厚度至微米级时的固化行为,在P元素质量分数低于3×10^-3%的PVC表皮上,当硅橡胶厚度低于2 μm时,硅橡胶出现不完全固化现象。 双组分加成型硅橡胶在含有P元素的PVC表皮表面的固化行为主要是由硅橡胶样品中铂催化剂总含量及PVC表皮中的P元素含量确定的,同时也会受到双组分加成型硅橡胶反应速率以及铂催化剂、P元素在硅橡胶中的扩散速率的影响。     

在线热裂解-气质联用分析缩合型和加成型硅橡胶

用在线热裂解-气质联用技术对缩合型硅橡胶和加成型硅橡胶分别进行分析,在其裂解产物中都检测到一系列的二甲基环硅氧烷环体.比较二者的裂解产物发现:缩合型硅橡胶非常容易发生裂解反应,产生低分子量的二甲基硅氧烷环体;而加成型硅橡胶相对难以裂解,有一定量的高级二甲基硅氧烷环体产生.除此之外还检测到微量的含氢环体和含乙烯基环体.这为缩合型和加成型这两种硅橡胶分析提供实验依据.     

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。     

双组份室温加成型硅橡胶口腔印模材料的制备

以自制乙烯基硅油为基胶、自制含氢硅油为交联剂、铂配合物为催化剂、高纯度硅微粉为填料、多乙烯基化合物为抑制剂等,通过实验制得双组份室温加成型硅橡胶口腔印模材料.研究了各组分对硅橡胶印模材料硫化化时间、细微复制、力学性能的影响.并制备了与国外产品性能相当的产品.     

双组分加成型硅橡胶交联固化过程的流变学研究

采用流变学方法研究了双组分加成型硅橡胶的交联固化过程,并研究了反应温度对反应速率的影响.随着加成反应的进行,体系中的交联程度逐渐增加;反应温度升高,硅橡胶完全交联固化所需时间减少.     

具有苯并噻唑环的二腈的聚合物

六十年代以来,国外对耐高温高分子,特别是耐高温杂环高分子,进行了大量工作,取得了很多成果,国内也进行了广泛的研究工作。但在这些工作中,既具有优良的耐高温性能,又具有良好的成型工艺性能,并能付诸实际应用的品种却不很多。我们根据自己的工作实践以及国外的一些发展趋势,认为先合成一种具有耐高温结构并含有能进行加成聚合的基团的单体或低聚物,然后在成型过程中聚合成交联结构,如此所得的高分子既具有耐高温性能,又可克服难以成型的缺点,适合作为增强塑料、模压塑料、涂料等方面的应用。对具体的结构设计,我们是这样考虑的:对耐温结     

耐高温聚酰亚胺树脂研究

综述了耐高温聚酰亚胺树脂及其碳纤维增强复合材料、耐高温聚酰亚胺超级工程塑料和高性能功能性聚酰亚胺薄膜等的研究进展。耐高温聚酰亚胺树脂包括第一代耐316℃系列、第二代耐371℃系列、第三代耐426℃3个系列的产品;耐高温聚酰亚胺超级工程塑料包括反应性热模压成型和高温注塑成型的材料;高性能聚酰亚胺薄膜包括透明性聚酰亚胺薄膜和抗原子氧PI薄膜树脂。本文介绍了它们的结构,工艺以及性能,并对其在航天、航空空间技术及微电子等其它领域中的应用情况做了简单的介绍。     

Thermal characterization of Al2O3 and ZnO reinforced silicone rubber as thermal pads for heat dissipation purposes

Silicone rubber filled with thermally conductive, but electrically insulating Al₂O₃ or ZnO fillers were investigated to be used as elastomeric thermal pads, a class of thermal interface materials. The effect of Al₂O₃ or ZnO fillers on the thermal conductivity and coefficient of thermal expansion (CTE) of the silicone rubber were investigated, and it was found that with increasing Al₂O₃ or ZnO fillers, the thermal conductivity of the thermal pads increases, while the coefficient of thermal expansion (CTE) decreases. The thermal conductivity results obtained were also analyzed using the Agari model to explain the effect of Al₂O₃ or ZnO fillers on the formation of thermal conductive networks. Thermal gravimetry analysis (TGA) showed that the addition of either Al₂O₃ or ZnO fillers increases the thermal stability of the silicone rubber, while the scanning electron microscope (SEM) showed that at 10 vol.% filler loading percolation threshold has yet to be reached.     

An investigation of dynamic mechanical, thermal, and electrical properties of housing materials for outdoor polymeric insulators

The present paper reports the results about a study of mechanical, thermal, dynamic mechanical and electrical properties of housing (weather shed) materials for outdoor polymeric insulators. Silicone rubber, ethylene-propylene-diene monomer (EPDM) and alloys of silicon-EPDM are known polymers for use as housing in high voltage insulators. The result of dynamical mechanical measurement shows that the storage modulus of blends enhances with increase EPDM in formulation. It can be seen from the result of TGA measurement that initial thermal degradation of silicone rubber improves by the effect of EPDM in blends. The blends of silicone-EPDM show good breakdown voltage strength compared to silicone rubber. Surface and volume resistance of silicone rubber improve by EPDM content. The mechanical properties of EPDM such as strength, modulus and elongation at break improve by silicone.     

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．     

Effects of functional graphene oxide on the properties of phenyl silicone rubber composites

Graphene oxide (GO) was treated with two types of surfactants, i.e., silane coupling agent (KH550) and 4,4’-diphenylmethane diisocyanate (MDI), incorporated into phenyl silicone rubber at a low concentration (≤0.2 wt%), and cured by the room temperature vulcanized method. The effects of functional graphene oxide on the dielectric behaviour, thermal conductivity, optical transmittance and mechanical properties of the composites were investigated. The results showed that the particle size changed after modification and that the modified GO dispersed well in the phenyl silicone rubber. The composites with MDI modified GO exhibited better electrical insulation and lower light loss in the ultraviolet–visible region than the composites with KH550 modified GO. However, composites filled with KH550 modified GO present better thermal conductivity.     

Improving Elasticity of Conductive Silicone Rubber by Hollow Carbon Black

Carbon black-based conductive rubber composites have important impacts on electromagnetic interference(EMI) shielding applications. However, an excessive amount of carbon black in the recipes of these conductive rubbers has caused their weak elasticity. Herein, hollow carbon black(HCB) particles were used to tune the elasticity of conductive rubber composites. Unique hollow morphology produced a better compression recovery of HCB than other solid carbon black, such as acetylene black. When the coupling agent was bonded to HCB, their conductive silicone rubber composites were featured by high stretching resilience, a fast compression recovery and excellent conductivity to satisfy the electromagnetic interference shielding requirements. Importantly, the rubber composites with coupling HCB had extremely low variations of mechanical property, conductivity and EMI shielding effectiveness after thermal accelerated aging tests. It is therefore revealed that the elasticity of HCB and its interfacial chemical coupling with rubber chains both play crucial roles in adjusting the elasticity of conductive rubber to sever long-term EMI protection.     

硅橡胶/蒙脱土复合材料的制备、结构与性能

用溶液法和熔融法制备了硅橡胶／蒙脱土复合材料，测定了力学性能、耐热性、耐溶剂性等性能．并与通常采用的２＃气相法白碳黑填充补强硅橡胶的性能作了对比．实验表明，溶液法能使蒙脱土更好地分散在硅橡胶基体中，所得到的复合物的性能有了很大的提高，与２＃气相法白碳黑填充补强的硅橡胶性能相当．     

Bubble-templated Construction of Three-dimensional Ceramic Network for Enhanced Thermal Conductivity of Silicone Rubber Composites

With the continuous development of the electronics industry, the energy density of modern electronic devices increases constantly,thus releasing a lot of heat during operation. Modern electronic devices take higher and higher request to the thermal interface materials.Achieving high thermal conductivity needs to establish an interconnecting thermal conductivity network in the matrix. For this purpose, the suspension of Al_2 O_3 and curdlan was first foamed to construct a bubble-templated continuous ceramic framework. Owing to the rapid gelation property of curdlan, we can easily remove moisture by hot air drying. Finally, the high thermally conductive composites are prepared by vacuum impregnation of silicone rubber. The result showed that composites prepared by our method have higher thermal conductivity than the samples obtained by traditional method. The thermal conductivity of the prepared composite material reached 1.253 W·m~(–1)·K~(–1) when the alumina content was 69.6 wt%. This facile method is expected to be applied to the preparation of high-performance thermal interface materials.     

Structure-Property Relationships in Rubber-Modified Styrenic Polymers

Styrenic polymers and copolymers are often impact modified with rubber particles. The efficiency of rubber toughening depends mainly on the size of the rubber particles and the degree of cross-linking. The deformation rate, the temperature, the orientation of the polymer molecules and the efficiency of rubber grafting also influence rubber toughening. It is thought that on impact, cavitation inside the rubber particles occurs which reduces the detrimental dilatational stress in the bulk polymer without forming cracks in the brittle matrix or at the rubber-matrix interface. Crazing and shearing are facilitated if the rubber particles can easily cavitate. This can be achieved by either avoiding too much cross-linking or by adding oil (silicone oil in the case of ABS) into the rubber particles, which acts as nuclei for void formation. An electron spectroscopic imaging method is described which allows visualizing the location of the oil. Already after cooling silicone oil modified ABS samples down to liquid nitrogen temperature rubber cavitation is observed. This cavitation is caused by the thermal stress developing due to the differences in thermal expansion coefficient between the rubber phase and the SAN-matrix and is facilitated by silicone oil. Voiding also leads to an increase of light scattering, which can be detected by an optical microscope using dark field illumination.     

填充粒子对复合型导电硅橡胶电阻温度特性的影响

研究了炭黑填充复合型导电硅橡胶的电阻温度特性,分析了升温过程中导电硅橡胶电阻特性的详细变化过程。研究了导电粒子和白炭黑含量对导电硅橡胶电阻温度特性的影响,测量了在不同热处理温度下电阻率的变化及加力时电阻的驰豫时间。分析了热处理对电阻特性影响的机理。     

Effect of rubber on properties of nylon-6/unmodified clay/rubber nanocomposites

Three nylon-6/unmodified clay/rubber nanocomposites with high toughness, high stiffness, high heat resistance and reduced flammability were studied in this paper, on basis of three compound powders of ultra-fine full-vulcanized powdered rubber (UFPR)/montmorillonite (UFPRM). It was found that all of the three UFPRs used in the study can help the silicate layers without organic treatment to be exfoliated in the nylon-6 matrix, despite some differences in compatibilities between them and nylon-6. Accordingly, the clay in different UFPRMs at the same loading content can lead to a similar improvement in stiffness and heat resistance of nanocomposites. In other words, UFPRs having different compatibilities with nylon-6 do not affect the stiffness and heat resistance of nanocomposites largely. However, the nylon-6 nanocomposites, modified with different UFPRMs, show different superior properties. Butadiene styrene vinyl-pyridine UFPRM (VP-UFPRM) is more effective in improving toughness of nylon-6. Nylon-6/silicone UFPRM (nylon-6/S-UFPRM) nanocomposite exhibits more reduced flammability, good flowability and high thermal stability. As for nylon-6/acrylate UFPRM (nylon-6/A-UFPRM) nanocomposite, it shows high toughness and thermal stability. Furthermore, the mechanism of unmodified clay exfoliation during the melt compounding and the effect of different UFPRs on the properties of the nylon-6/UFPRM nanocomposites are also discussed.