Pradhan Bratati, Srivastava Suneel Kumar, Saxena Anubhav
Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India.
J Nanosci Nanotechnol. 2012 Dec;12(12):8975-84. doi: 10.1166/jnn.2012.6728.
The present work deals with the preparation and characterization of silane grafted MMT (S-MMT), organomodified MMT (O-MMT) and silane grafted organomodified montmorillonite (OS-MMT) reinforced silicone rubber (SR) nanocomposites. XRD of SR filled with O-MMT (1-8 wt%), OS-MMT (1-8 wt%) and S-MMT (1-5 wt%) suggested the formation exfoliated morphology, which has also been supported by the corresponding TEM images of 3 wt% filled SR nanocomposites. TGA and DSC studies of SR/OS-MMT (3 wt%) nanocomposites have shown that the thermal stability, glass transition temperature and crystallization temperature are maximum improved with respect to neat SR by 50, 14 and 10 degrees C respectively. This is attributed to the synergistic effect of organo-modification followed by amino silane grafting of MMT on thermal properties of SR. The tensile strength of SR/S-MMT (5 wt%), SR/O-MMT (3 wt%) and SR/OS-MMT (3 wt%) relatively improved by 134, 312, and 259% respectively suggesting that the synergistic effect of OS-MMT is not effective in reinforcing the mechanical properties of SR. In all probability, the curing of SR through hydrosilylation is inhibited by the lone pair on nitrogen in NH2 group of OS-MMT.
本工作涉及硅烷接枝蒙脱土（S-MMT）、有机改性蒙脱土（O-MMT）和硅烷接枝有机改性蒙脱土（OS-MMT）增强硅橡胶（SR）纳米复合材料的制备与表征。填充O-MMT（1-8 wt%）、OS-MMT（1-8 wt%）和S-MMT（1-5 wt%）的SR的XRD表明形成了剥离形态，3 wt%填充SR纳米复合材料的相应TEM图像也证实了这一点。SR/OS-MMT（3 wt%）纳米复合材料的TGA和DSC研究表明，相对于纯SR，其热稳定性、玻璃化转变温度和结晶温度分别最大提高了50、14和10摄氏度。这归因于MMT的有机改性随后氨基硅烷接枝对SR热性能的协同效应。SR/S-MMT（5 wt%）、SR/O-MMT（3 wt%）和SR/OS-MMT（3 wt%）的拉伸强度分别相对提高了134%、312%和259%，这表明OS-MMT的协同效应在增强SR的机械性能方面并不有效。很可能，OS-MMT中NH2基团氮上的孤对电子抑制了SR通过硅氢加成的固化。
