Pultruded Carbon Fiber/Vinyl Ester Composites Processed with Different Fiber Sizing Agents. Part Ⅲ: Theoretical Aspects

摘要

This paper addresses proposed improvements to the carbon/vinyl ester interface via the use of engineering thermoplastic polymers as sizing agents. Two thermoplastic polymers, K-30 poly(vinylpyrrolidone) (PVP) and a modified polyhydroxyether of Bisphe-nol A (Phenoxy™) were used as sizings in a controlled study. These sizings were applied to surface treated but unsized AS-4 carbon fibers using a lab-scale sizing line. The standard and commercially available G′ sized AS-4 fiber, was also used for comparison. Predictions of observed tensile and compression strengths of unidirectional, sized carbon fiber-vinyl ester composites fabricated using the pultrusion process were assessed using micromechanical models that take into consideration the influence of the different interfaces. The microme-chanical models require inputs on either the interfacial shear strength or the global laminate shear response. The influence of both processing induced differences (misalignment of fibers and fiber damage) as well as the differences in interphase properties (shear response) have been shown to play an important role in describing the observed differences in the interphase varied composites.