U.S.-Bulgarian Research on Microfibrillar-Reinforced Polycondensate Blends

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9307812 Schultz This grant supports U.S.-Bulgaria joint cooperative research on "Microfibrillar-Reinforce Polycondensate Blends" between Dr. Jerold M. Schultz of the University of Delaware and Dr. Stoyko Fakirov of the Laboratory on Structure and Properties of Polymers, Sofia University, Bulgaria. Previously, the researchers showed that incompatible polycondensate blends of unusually high uniaxial mechanical properties can be produced through a three- stage process: (1) uniaxial cold-drawing; (2) heat-treatment above the melting or softening temperature of the discontinuous phase; and (3) continued heat-treatment in a temperature range consistent with solid-state exchange reaction. Indications are that fibrillar crystals or glass are formed in the first stage, and the "matrix" is relaxed in the second. The most unusual stage is the third, where the fibril/matrix interface appears to be compatibilized through an exchange reaction. With this grant, the preceding process will be further studied, to characterize and test all phases of the suggested structure development. Kinetic studies of interfacial exchange reactions in model incompatible systems will be followed by spectroscopic and other means. The researchers will examine the microfibrillar microstructural hypothesis using transmission electron microscope methods developed recently in their laboratory and also by small-angle x-ray scattering. They will follow changes in chain orientations with processing time and temperature, using infrared dichronism. They will measure mechanical properties of selected materials and fit them to models they developed using microstructural characterizations. This research in materials science fulfills the program objectives of advancing science by enabling leading experts in the U.S. and Bulgaria to combine complementary talents and pool research resources in areas of strong mutual interest and competence.