Controlling the morphology in epoxy/thermoplastic systems
Résumé
Thermosets are frequently toughened by a high-T g thermoplastic (TP). Blend morphologies, obtained by curing induced phase separation with scales of a few hundreds of nanometers are relevant for highperformance applications, but no quantitative description for obtaining these morphologies exist yet. We propose such a quantitative approach for predicting and controlling the final morphology. The key is the degree of curing and the corresponding T g of the blend and of both phases when phase separation takes place. It is controlled by the Flory interaction parameter of the constituents and their respective T g 's. We show that if phase separation takes place too early during curing, the T g is too low and morphologies grow to reach sizes of a few micrometers, or more. Our study of different systems allows us to propose the relevant range of Flory interaction parameter and temperature window T-T g for which the sizes of interest may be obtained. Our work opens the way for devising thermoplasticsthermosets couples with the appropriate affinity and T g s in order to make blends with tailored morphologies.
Domaines
Polymères
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