Pre-intercalation of long chain fatty acid in the interlayer space of layered silicates and preparation of montmorillonite/natural rubber nanocomposites

A series of long chain fatty acids was intercalated into the interlayer space of organo montmorillonite (OMt) and a gradual expansion of the interlayer space was observed as the chain length of the fatty acid increased. The fatty acid with 22 carbon atoms (docosanoic acid) was found to offer a highest interlayer space among the fatty acids under consideration. This fatty acid was selected further to modify OMt and subsequently utilized as reinforcing fillers in natural rubber (NR) matrix. Wide angle X-ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy and contact angle measurement indicated successful intercalation of the fatty acid into the interlayer space of the clay minerals. The main objective of such intercalation is to make clay minerals suitable for the preparation of rubber nanocomposites, especially when using non-polar rubbers. Docosanoic acid intercalated Mt was successfully dispersed in NR matrix as confirmed by WAXD and transmission electron microscopy (TEM). As a result, the mechanical properties were found to be improved in a remarkable way. Improvement of ~ 114% in tensile strength and ~ 203% in modulus at 300% elongation was observed. These results were correlated with the morphological data obtained from WAXD and TEM.