CPS 758 Untersuchung des Mischungsgleichgewichts binärer Polymermischungen |
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Authors: | K -H Illers W Heckmann J Hambrecht |
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Institution: | 1. Kunststofflaboratorium der BASF Aktiengesellschaft, Ludwigshafen am Rhein, Deutschland
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Abstract: | The phase diagram of a binary polymer blend can be derived from the glass temperaturesT g of the demixed phases under the following conditions: - The Tg's of the pure components are sufficiently different from one another.
- TheT g 's of the one-phase homogeneous mixtures can be determined and vary monotonically with composition.
- The equilibrium state of the mixture is attained after sufficient long annealing at temperatureT.
- The equilibrium state at the temperatureT can be frozen by quenching.
These conditions are examined for mixtures of polystyrene (PS) and tetra methyl-bis-phenol A-polycarbonate (TMPC). The phase separation kinetics is investigated with respect to size and composition of the co-existing phases. The co-existance curves (binodal with lower critical point) are determined for mixtures with various molar masses of the PS component. The problems concerning the cloud point curves are shortly discussed. BetweenT g and the binodal the one-phase mixtures exist in a hindered thermodynamic state, because the crystallization of the TMPC component is a very slow process which requires very long annealing. With increasing amounts of PS in the mixture the crystallization half time of TMPC is lowered. |
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