Page 307 - Engineered Interfaces in Fiber Reinforced Composites

288 Engineered interfaces in fiber reinforced Composites

A 200
Prediction
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(b) TEMPERATURE (T)
Fig. 7.5. (a) Transverse impact fracture toughness and (b) fiber pull-out length versus testing temperature
for carbon fiber-epoxy matrix composites with and without PVAL coatings on fibers. After Kim and
Mai et al. (1991b).
chemical bonding between the functional groups present in the fiber surface and
epoxy matrix.
Several different thermoplastic materials including, polyamide (PA), polyether
sulfone (PES), polycarbonate (PC), polysulfone (PS), polyetherimide (PEI) and
polymethyl methacrylate (PMMA), were also found to have significant effects on the
mechanical properties of carbon fiber-nylon matrix composites (Tomlinson and
Barnes, 1992). Polyamide nylon 6.6 coating on carbon and Kevlar fibers for epoxy
matrix composites by in-situ polymerization techniques were also shown to be
effective for promoting localized plastic deformation around the crack tip and
protecting the brittle fiber surface during processing (Skourlis et al., 1993; Duvis
et al., 1993). The thermoplastic coatings have advantages over other coating
materials in that they would form a microductile layer at the interface (Dauksys,
1973). The interlayer functions satisfactorily as a stress relief medium in reducing the