蒙脱土填充补强丁苯橡胶及对橡胶硫化特性的影响

MONTMORILLONITE REINFORCED SBR AND EFFECT ON THE VULCANIZATION OF RUBBER

以十八烷基三甲基溴化铵为插层处理剂改性蒙脱土。分别采用有机蒙脱土(C18 MMT)和Na 蒙脱土(Na MMT)填充补强丁苯橡胶, 用XRD和TEM对复合材料的结构进行表征。结果表明: 蒙脱土在橡胶基体中的分散取决于蒙脱土的亲油性, 亲油性越强, 蒙脱土的片层在橡胶中的分散越均匀, 完全有机化处理的蒙脱土能够被剥离成厚度为20 nm左右的片层并均匀分散在橡胶基体中。蒙脱土的存在对橡胶的硫化反应有一定的影响, 有机蒙脱土对橡胶硫化反应有催化作用, 但不改变硫化反应的活化能; Na 蒙脱土片层阻碍了橡胶的硫化交联, 使交联反应对温度的敏感性降低, 导致表观活化能减小。有机蒙脱土填充补强丁苯橡胶, 由于提高了橡胶的交联密度, 同时有机蒙脱土具有高比表面积和滑移性, 大大提高了橡胶的机械性能, 其拉伸强度和300%定伸应力与炭黑N330补强橡胶相当, 而断裂伸长率较炭黑补强橡胶有大幅度的提高, 在替代炭黑作为橡胶的补强剂方面具有广泛的应用前景。

SBR/C18-MMT and SBR/Na-MMT composites were prepared through a melt intercalation process. The results of XRD and TEM observation show that the dispersion of montmorillonite layers in SBR matrix is determined by the hydrophobic property of the layers. Organic treated montmorillonite could be exfoliated into layers with about 20 nm in thickness and uniformly dispersed in the SBR matrix. The effects of montmorillonite on the vulcanization reaction of SBR were determined by DSC method. The vulcanization curves show that the existence of C18-MMT accelerates the vulcanization reaction and the activation energy is not changed. For the SBR reinforced by Na-MMT, the vulcanization was impeded and the sensitivity of reaction to temperature was decreased, which resulted in the decrease of apparent activity energy. Due to the nanoscale dispersion of layers of C18-MMT and the enhanced crosslinking density of rubber matrix, the mechanical properties of SBR dramatically increase. The tensile strength and 300% modulus of SBR/C18-MMT nanocomposite were correspondent to the SBR reinforced by equal content of carbon black N330 while the elongation at the break of the nanocomposite was much higher, which is related to the slipping and oriented arranging of the C18-MMT layers in the composite under tension.