Authors: J. Carretero-González, R. Verdejo, S. Toki, B.S. Hsiao, E.P. Giannelis, M.A. Lopez-Manchado
Affilation: Polymer Science and Technology Institute, Spain
Pages: 838 - 839
Keywords: strain-induced crystallization, nanocomposite, natural rubber, organoclay
Polymer nanocomposites (PNCs) represent an alternative new class of materials compared to conventional filled polymers or polymer blends, as they can possess enhanced properties through nanoscale reinforcement. A great deal of efforts have been devoted to understand the reinforcing mechanism of PNCs containing highly anisotropic nanofillers such as nanoclays. In this study, we present experimental evidence of a remarkable enhancement of strain-induced crystallization in natural rubber (NR) nanocomposite under uniaxial stretching due to the presence of nanoclay particles. By using synchrotron wide-angle X-ray diffraction (WAXD), we have monitored the structure changes during deformation in real time. The behavior of significantly enhanced strain-induced crystallinity in organoclay/NR nanocomposites has not been observed before in systems containing conventional fillers. This effect might be responsible for the observed enhancement in mechanical properties of organoclay/NR nanocomposites. The results suggest a dual crystallization mechanism in nanocomposites, which is absent in the unfilled system. The mechanism consists of spatial reorganization of organoclay at low strains (e.g. less than alpha = 3), followed by rapid strain-induced crystallization of NR. The in-situ observed structure changes in NR nanocomposite enable us to suggest a mechanism that may be universal to crystallizable elastomers containing nanosized fillers.