ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
A nearly symmetric critical mixture (φc=0.486) of perdeuterated and protonated 1,4-polybutadiene exhibiting an upper critical solution temperature Tc=61.5±1.5 °C has been quenched from the homogeneous state ((approximately-equal-to)75 °C) to various temperatures between 25 and 57.5 °C. Light scattering measurements document the subsequent spinodal decomposition process which we describe based on a four-stage model: early, intermediate, transition, and final. The early stage is accounted for by the Cahn theory, yielding initial correlation lengths and effective diffusion coefficients in quantitative agreement with mean-field predictions. Nonlinear effects mark the beginning of the intermediate stage, which exhibits a simple power-law growth of heterogeneity length Lm(t)∼tneff, but with a temperature dependent exponent neff. As the composition fluctuation amplitude approaches the equilibrium values, the spinodal decomposition process enters the transition stage, characterized by a decreasing interfacial thickness and an increasing Lm(t). Once the interfacial profile equilibrates, a crossover to the final stage occurs. Subsequent growth of L(t) leaves the morphology unaffected as evidenced by a universal structure factor. These findings are discussed in the context of the current theory and are compared with prior studies involving polymer–polymer and simple liquid mixtures.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.456901
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