Kinetics of phase separation in ramified polymer blends of arbitrary topology |
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Authors: | N?Ghaouar Email author" target="_blank">M?BenhamouEmail author A?Derouiche A?Gharbi |
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Institution: | (1) Laboratoire de Physique des Polymères et Phénomènes Critiques, Faculté des Sciences Ben M sik, B.P. 7955 Casablanca, Morocco;(2) Laboratoire de Physique de La Matière Molle, Faculté des Sciences de Tunis, Tunisia |
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Abstract: | We present here a theoretical study of kinetics of phase separation within a mixture made of two chemically incompatible ramified polymers. For simplicity, we assume that they have the same topology. We are interested in the variation of the relaxation rate, q, versus the wave number q, in the vicinity of the spinodal temperature. The kinetics is governed by local (Rouse) and reptation motions (faster and slower modes). For qRG 1 (RG being the gyration radius), kinetics is entirely controlled by local motions where each chain moves inside its own tube, and we show that the corresponding characteristic frequency, {-1}q, scales as {-1}q
Gq6, where G is a known topological factor. For qRG 1, however, kinetics is rather dominated by long-wavelength (reptation) motions where unlike ramified polymers creep inside a long tube. For this case, we find that {-1}q
( 0 )q2 ( c - ), where ( 0 ) is another known topological factor that represents the total mobility of free monomers belonging to connected chains and reticulation points, and c accounts for the critical value of the segregation parameter. Finally, the derived relaxation rate must be compared to that relative to a linear polymer mixture. |
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Keywords: | 61 25 Hq Macromolecular and polymer solutions polymer melts swelling 64 75 +g Solubility segregation and mixing phase separation |
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