【作者】 贾超；

【导师】 卢咏来；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2011， 硕士

【摘要】 硅橡胶是使用温度范围最宽的弹性体材料,是应用最广泛的空间密封材料之一,但硅橡胶的气密性是所有弹性体材料中最低的。应用高形状系数的片状黏土填料对SiR进行改性,可提高其气体阻隔性,但如何达到纳米分散是关键难点问题。本论文工作研究了硅橡胶／有机改性黏土(SiR/OMMT)纳米复合材料的制备方法和工艺、采用XRD和TEM表征了OMMT插层结构及其在基体中的分散情况；研究了复合材料结构与气体阻隔性能和力学性能间的关系,主要如下：1.使用机械搅拌法将加成硫化的液体硅橡胶(LSR)与有机黏土混合制备SiR/OMMT复合材料。结果表明,对混炼胶进行高温热处理有助于硅橡胶在黏土间的插层；但OMMT在低黏度的LSR中难于达到纳米分散,获得的复合材料性能较差。2.采用熔体共混法将五种类插层改性剂改性的OMMT与甲基乙烯基硅橡胶(MVQ)进行混合制备SiR/OMMT复合材料。结果发现：OMMT插层剂的极性及OMMT的初始层间距对复合材料中OMMT的插层结构及其空间分散有显著影响,具有最大初始层间距的I.44P OMMT在SiR中分散状态最好,达到了纳米分散。随着填充量的提高,混炼胶料的黏度增大、OMMT在SiR中的分散状态逐渐改善,获得的纳米复合材料的力学性能与气体阻隔性较纯SiR都有明显提高,填充30份OMMT (I.44P)的纳米复合材料其透气率为纯胶的69%。3.为提高复合材料体系的黏度,在混入OMMT之前在MVQ中预先混入20份气相法白炭黑(FS)制备三元复合材料。实验表明,通过加入FS可进一步提高OMMT在MVQ中的分散。FS对MVQ的气密性没有影响,但在其作用下,复合体系气体阻隔性能提高,透气率降低到纯SiR的60%(30份OMMT)。4.使用不同用量的羟基硅油(FS的结构控制剂)对OMMT (I.44P)进行预先插层以增大OMMT的初始片层间距,再其经机械混入了预混20份FS的MVQ硅橡胶中制备三元纳米复合材料,可使OMMT在SiR中的分散情况进一步得到改善。随羟基硅油用量的提高,复合材料的气密性和断裂伸长率逐渐增大,但拉伸强度有所下降。5.使用机械共混法将具有优良力学性能的商品化硅橡胶混炼胶与OMMT混制备纳米复合材料。结果表明,因该硅胶混炼胶的黏度大,OMMT在SiR中的分散情况更好,复合材料的力学性能与气体阻隔性能都较为理想。当黏土填充量为30份时,OMMT纳米复合材料的透气率为未添加时的50%。更多还原

【Abstract】 Silicone rubber (SiR) is a kind of elastomer with the largest use temperature range, and also one of the most widely used space sealing materials. But the gas barrier property of silicone rubber is the lowest among all elastomer materials. Clay sheet with high shape factor has been used to SiR to improve its gas barrier properties, but how to achieve the nano-dispersion is the key and difficult problems. This preparation methods and techniques of silicone rubber/organic modified montmorillonite (SiR/OMMT) nanocomposites were studied in this work; XRD and TEM characterization were used to characterize the intercalated structure of OMMT and the OMMT dispersion in the matrix; the relationship between the material structure and properties was revealed. The results showed as follows:1. Mechanical mixing method was used to blend liquid silicone rubber (LSR) and OMMT to prepare SiR/OMMT composites. The results showed that high temperature heat treatment play a good role to the clay intercalated; it is difficult to achieve nano-dispersion for OMMT in the LSR with low viscosity, so the LSR/OMMT composites performance poor properties. 2. Five different types of organically modified montmorillonites (OMMT) were incorporated into silicone rubber (SiR) respectively by melt blending. The results revealed that the organic intercalants or silane coupling agent having higher polarity might play the negative roles in the melt intercalation; and the higher the OMMT initial interlayer spacing, the easier the intercalation. The intercalated structure in the SiR/I.44P OMMT nanocomposite has the largest interlayer spacing and the best spatial dispersion of OMMT. The OMMT dispersion improves with increasing OMMT dosage. The gas barrier property of the SiR is obviously improved by the incorporation of OMMT. The nitrogen gas permeability coefficient of the SiR/OMMT nanocomposite is lower than that of pure SiR by 30% at an OMMT loading of 30 phr.3. In order to further improve the OMMT dispersion in SiR,20 phr fumed silica (FS) was added to the compound prior to mixing OMMT for increasing viscosity of the compound and mechanical shearing force during compounding OMMT. The results shown that though FS have no effects on the gas barrier properties of SiR/FS composites, the SiR/OMMT/FS ternary nanocomposites exhibit improved dispersion of OMMT and better gas barrier properties than the binary counterparts. The N2 gas permeability coefficient of SiR/OMMT/FS(100/30/20) nanocomposites decreases nearly 40% compared to net SiR.4. Hydroxyl silicone oil with different dosage (FS structural control agent) on the OMMT (I.44P) pre-intercalation to increase the initial lamellar spacing of OMMT, and then mechanically mixed with the premix of the MVQ Silicon 20 FS Preparation of rubber ternary nanocomposites, can OMMT dispersion in the SiR in further improvement. With the increased amount of silicone oil composites tightness and elongation at break increases the tensile strength decreased.5. Using mechanical blending method has excellent mechanical properties of commercial silicon rubber compound mixed with the preparation of OMMT nanocomposites. The results show that, due to the viscosity of the silicone rubber, OMMT dispersion in the SiR in better mechanical properties of composite materials with gas barrier properties are more desirable. When the clay content of 30 phr filled, OMMT nanocomposites was not added when the permeability of 50%.更多还原