Remarkable reinforcement of natural rubber by deformation-induced crystallization in the presence of organophilic montmorillonite

A remarkable reinforcement of natural rubber (NR) was achieved by adding a low content of organically modified montmorillonite (OMMT). Mechanical tests demonstrated that the most noticeable enhancement in the tensile strength of NR was at a OMMT content of 5 wt.%. In order to gain further insight into the mechanism of reinforcement by OMMT, the deformation-induced crystallization behavior and morphology of NR/OMMT nanocomposites with different OMMT contents were investigated by synchrotron wide angle X-ray diffraction and transmission electron microscopy. The results show that the variation in the degree of strain-induced crystallization is consistent with that of tensile strength. The peak in tensile strength at 5 wt.% OMMT content can be ascribed to the fact that strain-induced crystallization is the essential factor in reinforcement of NR. Further, the nanomorphology of OMMT dispersed in a NR matrix plays a decisive role in the crystallization behavior of NR during deformation. An increase in the exfoliation of OMMT leads to an increase in the promotion of deformation-induced crystallization of NR.