Nylon 66/poly(vinyl pyrrolidone) reinforced composites: 2 bulk mechanical properties and moisture effects

The effect of interphase microstructure on the bulk mechanical properties and moisture absorption of Nylon 66 reinforced with E-glass or high-modulus (AS4) carbon fibers was examined. These particular composite systems were chosen because of their propensity to form distinct transcrystalline interphases. A comparison of mechanical properties was made by dynamic mechanical analysis (DMA) and Minimat off-axis tensile testing of samples with and without this unique interphase. Moreover, a newly developed vibrational testing technique was used and correlated with DMA to ascertain changes in the damping characteristics of the composites. The major contribution of this work is the systematic translation of single-filament (microscopic) results to bulk composite mechanical properly results in the same well-characterized system. This was accomplished by studying both glass- and carbon-fiber/Nylon 66 composites. The E-glass- and carbon-fiber-reinforced Nylon 66 composites have better ultimate properties when the transcrystalline interphase is absent, but the composites have better damping properties when transcrystallinity is present. Finally, upon moisture exposure, suppression of the glass transition temperature was evident, as the water served as a plasticizer in all composites. The presence of transcrystallinity did not alter the adsorption kinetics of the composites. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.