Springer Online Journal Archives 1860-2000
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Abstract Tensile (293 K), dynamic (210 to 570 K, 0.3 Hz), and ultrasonic (293 K, 5 MHz) moduli were determined for various epoxy networks based on epoxide or amine mixtures. Crosslink density and glass transition temperature have an insignificant influence on the elastic properties in glassy state which are mainly controlled by the cohesive energy. Various methods of modulus prediction from structure were compared and discussed. They have generally a low predictive value because many types of hydrogen bonds, having very different contributions to the cohesion, coexist in epoxies. An interesting correlation was found between ultrasonic moduli and water absorption. The incidence of beta relaxations on the elastic properties determined at room temperature and low strain rate was examined. It appeared that an internal plasticizer as aniline increases the glassy state rigidity by suppression of the beta relaxation without noticeable change of packing density. A possible generalization of this latter result was discussed.
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