Morphology study of rubber based nanocomposites by transmission electron microscopy and atomic force microscopy

Rubber based nanocomposites were prepared using octadecyl amine modified Na-montmorillonite clay (OC) and Styrene Butadiene Rubber (SBR) having styrene content of 15, 23 and 40% respectively and Acrylonitrile Butadiene Rubber (NBR) having acrylonitrile content of 19, 34 and 50% respectively. The morphology of the nanocomposites was investigated using Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM) and X-ray Diffraction Technique (XRD). The TEM photographs of the unmodified clay loaded SBR nanocomposite showed agglomeration, while the modified clay loaded SBRs of all the grades revealed complete exfoliation. The NBRs, on the other hand, gave unexfoliated and intercalated clay structures both with the unmodified and the modified clays, except in the case of NBR having 19% of acrylonitrile and 4% of the unmodified clay. The AFM data were in good accord with the TEM results. The particle dimensions were within the range of 10–20 nm in the case of SBR sample having 4 parts of the modified clay. NBRs having 34 and 50% acrylonitrile contents and 4 parts of OC showed clay particles ranging from 50–70 nm and 70–100 nm respectively. On comparison of the rubbers having different nature and contents of functional groups and filler loadings, significant effect on the morphology of the composite was observed. The nature of solvent used to prepare the nanocomposites also affected the morphology. XRD data further corroborated the facts in all the above cases.