Real time Crystallization of Nanoparticles Filled Natural Rubber Under Stretching

Keywords:
strain-induced crystallization, nanocomposite, natural rubber, organoclay

Abstract:
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.[1] A great deal of efforts have been devoted to understand the reinforcing mechanism of PNCs containing highly anisotropic nanofillers such as nanoclays.[2] 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.[3] 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.

Nanotech 2008 Conference Program Abstract