Investigation of the T sub ll (> T sub g) Relaxation in Homopolymers and Block Copolymers of Styrene by Torsional Braid Analysis.
Technical rept. no. 13, Dec 76-Dec 77,
PRINCETON UNIV N J DEPT OF CHEMICAL ENGINEERING
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Investigation of the T sub ll T sub g relaxation in amorphous polymers of styrene by the technique of torsional braid analysis has been reviewed. For the most part the relaxation behaves like the glass transition T sub g in its dependence on molecular weight, on average molecular weight in binary polystyrene blends, and on composition in a polystyrene homogeneously plasticized throughout the range of composition. Diblock and triblock copolymers also display a T Tg relaxation above the Tg of the polystyrene phase. Two results in particular suggest that the T sub ll relaxation is molecularly based. 1 The temperature T sub ll is determined by the number average molecular weight for binary blends of polystyrene when both components have molecular weights below Mc the critical molecular weight for chain entanglements. 2 Homopolymers, and diblock and triblock copolymers of styrene, have a T T sub g relaxation at approximately the same temperature when the molecular weight of the styrene block is equal to that of the homopolymer. Author
- Ceramics, Refractories and Glass