Bulletin of the American Physical Society
2006 Ohio Section of the APS Fall Meeting
Friday–Saturday, October 13–14, 2006; Orrville, Ohio
Session D3: Elastomeric Materials |
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Chair: Jutta Luettmer-Strathmann, The University of Akron Room: Wayne College A106 |
Saturday, October 14, 2006 9:30AM - 9:42AM |
D3.00001: How Does Rubber Crystallize Upon Application of Strain Mindaugas Rackaitis, Xiaorong Wang Strain induced crystallization of natural and synthetic rubbers is one of the most interesting phenomena in the field of rubber science and technology. Most of the research in the field was done using X-ray diffraction techniques. However up to this day there are no reports of direct observation of strain induced crystallization of rubber. This presentation reports first atomic force micrographs of high cis polybutadiene rubber surface at various strains. The crystallization of the rubber was confirmed by X-ray diffraction and crystallite orientation is discussed. [Preview Abstract] |
Saturday, October 14, 2006 9:42AM - 9:54AM |
D3.00002: Fluctuations and critical phenomena of a filled elastomer under deformation Mindaugas Rackaitis, Xiaorong Wang Fluctuations and critical phenomena have drawn much attention for many years. But, no report anticipates that an elastomer containing fillers under gentle deformations will show similar effects. In this letter, we discover for the first time that a filled rubber system under about 2{\%} strain may display feature fluctuations that could be associated with a transition of the filler from an elastic solid state to a dispersed fluid state and that is reminiscent of critical phenomena. In addition, we show that the fluctuation of macroscopic parameters can be related to the microscopic fluctuation of filler structures in the rubber compound and in principle it can act as a probe of what is happening physically at the microscopic scale. [Preview Abstract] |
Saturday, October 14, 2006 9:54AM - 10:06AM |
D3.00003: Ultrasound Treatment of Polyisoprene Rubber, Studied by NMR Relaxation and Diffusion. E. von Meerwall, X.M. Sun, T. Joshi, A.I. Isayev In support of rubber recycling, we have studied the effect of intense ultrasound on unfilled cis-polyisoprene (PI) melts and networks using proton NMR T2 relaxation and pulsed-gradient diffusion. At 70.5 deg.C the echo decays show two components, due to entangled sol and crosslinked network; and unentangled sol, dangling ends, and oligomers. Component T2 values, hence intermolecular mobilities, increase with sonication, with modest changes in relative amplitudes. The high melt molecular weight(M) without a low-M tail precluded diffusion measurements. We then examined PI melts degraded by ultrasound with and without subsequent vulcanization. Here the T2 decays are consistent with three components. Sonication shifts and broadens the M-distribution but produces no network. Curing generates at least 94\% network, lowers all mobilities, and decreases the proportions of unentangled sol and of oligomers. The diffusion spectrum is bimodal, arising from intermediate fractions and oligomeric species. Both diffusion rates and all T2 values increase slightly with ultrasound amplitude. We compare these results with our earlier work in natural rubber. [Preview Abstract] |
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