Mechanical Property Modification and Morphology of Poly(styrene-b-hydrogenated butadiene-b-styrene)/ Poly(hydrogenated butadiene) Blends
| Autor: | J.P. Baetzold, X. Quan, I. Gancarz, J.T. Koberstein |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
chemistry.chemical_classification
Materials science Polymers and Plastics Organic Chemistry Polymer Dynamic mechanical analysis Small-angle neutron scattering Styrene Inorganic Chemistry chemistry.chemical_compound Chemical engineering chemistry Polymer chemistry Materials Chemistry Copolymer Lamellar structure Polystyrene Solubility |
| Zdroj: | Macromolecules. 27:5329-5340 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/ma00097a012 |
| Popis: | The mechanical properties and morphology of a series of triblock copolymer blends with midblock associating homopolymers of varying molecular weight (Mw) have been characterized. The symmetric triblock copolymer studied contains polystyrene endblocks and midblocks of hydrogenated poly(1,2-butadiene) and is mixed with hydrogenated poly (1,2-butadiene) homopolymers of Mw both below and above that of the copolymer midblock. The rubbery plateau modulus determined by dynamic mechanical spectroscopy increases with increasing Mw of the homopolymer at fixed overall homopolymer content. At fixed Mw, the composition dependence of the plateau modulus is complex and shows unusually synergistic behavior. For high Mw homopolymers the plateau modulus increases initially upon homopolymer addition. Small angle neutron scattering and TEM are employed to determine the morphological changes. In all cases, the blends exhibit a lamellar microphase structure, with homopolymer macrophases apparent at high homopolymer contents. The apparent homopolymer solubility limits are found to be inversely related to the homopolymer Mw. The results indicate that the lamellar repeat distance decreases upon addition of the lowest Mw homopolymer and that the microdomains swell in blends containing homopolymers with Mw similar to that of the midblock sequence and are unchanged for high Mw homopolymers with negligible solubility. The results suggest thatmore » the interesting mechanical response of the blends can be explained by consideration of the changes in their entanglement structure resulting from confinement of the homopolymer chains within the highly constrained environment of the midblock lamellae.« less |
| Databáze: | OpenAIRE |
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