Structural evolution during uniaxial deformation of natural rubber reinforced with nano-alumina

The mechanical properties of natural rubber (NR) were enhanced by the inclusion of nano-alumina. In order to gain further insights into the reinforcement mechanism, synchrotron wide-angle X-ray diffraction (WAXD) was used to monitor the evolution of the molecular structure during stretching in real time, and the tube model theory was applied to study the effect of nanoparticles on rubber network. For the filled rubber, the onset strain of crystallization shifted to much lower value compared with that of the unfilled, indicating the presence of special strain amplification effect, which can be revealed by the reduction of configurational entropy. In addition, the crystallinity increased and the lateral crystallite size decreased after the addition of the nanofiller. During deformation, the crystallites of the filled rubber showed lower orientational fluctuations differing from that of NR reinforced by carbon black. Copyright (C) 2010 John Wiley & Sons, Ltd.