Bond-induced ergodicity breakdown in reactive mixtures.
We have studied by inelastic x-ray scattering, at wave vectors 1 nm < or =q< or =15 nm(-1), the high-frequency dynamics of epoxy-amine mixtures as the monomers irreversibly polymerize. We find that chemical bonding, while inducing molecular ordering on a mesoscopic length scale, also efficiently realizes the mechanism of dynamical arrest described by the mode-coupling theory, as manifested by a cusp singularity in the behavior of the nonergodicity factor as a function of the number of chemical bonds. These results confront positively the mode-coupling theory with a new control parameter.
Corezzi
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INFM CRS-SOFT, c/o Università di Roma La Sapienza, P. A. Moro 2, I-00185 Roma, Italy.
Comez
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Monaco
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Verbeni
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Fioretto
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