This paper presents the results of an experimental investigation of the effects of voids upon the hygral and mechanical properties of AS4/3502 graphite/epoxy. Simple uniaxial tension tests were employed to determine the effects of voids upon ply moduli E11, E22 and G12, and the Poisson ratio ν12. The matrix dominated moduli E 22 and G12 were found to depend significantly upon void content while little dependence was noted for the fiber dominated properties E11 and ν12. Moisture conditioning experiments showed that both the rate and the equilibrium level of moisture sorption depend upon void content. In addition, non-Fickian diffusion anomalies were observed in high void content specimens while specimens with low void content displayed classical Fickian behavior.

A Note on the Effects of Voids Upon the Hygral and Mechanical Properties of AS4/3502 Graphite/Epoxy

The objective of the research was to determine if ballast fiber reinforced polymer composites are feasible, practical, and a beneficial material alternative for transportation applications. No significant differences in stiffness and strength were found between basalt fabric reinforced polymer composites and glass composites reinforced by a fabric of similar weave pattern. Aging results indicate that the interfacial region in basalt composites may be vulnerable to environmental damage than in glass composites. However, the basalt/epoxy interface may also be more durable than the glass/epoxy interface in tension-tension fatigue because the fatigue life of basalt composites is longer. A wider disagreement between the literature properties of basalt fibers and the properties measured in this study renders any further consideration of basalt reinforced composites highly problematic. Composites manufacturing issues with basalt fabric were also investigated. The measurement results of the in-plane permeability for basalt twill 3x1 fabric material showed that a high correlation exists between the two principal permeability values of the fabric. This is in contrast to the lack of correlation found in other weave patterns and may point to an important material selection criteria for mass production of composites by liquid molding.

Basalt Fiber Reinforced Polymer Composites

The utilization of reinforced plastic composites is generally limited by their sensitivity to long-term environmental exposure. Glass-reinforced thermosetting polymers in particular are detrimentally affected, reversibly and/or irreversibly, by exposure to water vapor or liquid water. A reinforced composite consists of three mutually interacting regions: fiber, matrix, and the fiber/ matrix interface. Each region may, for purposes of convenience, be further subdivided according to its location or properties. Most common is the listing of regions comprising the “interface”: glass/ coupling agent interface, the coupling agent polymer itself, and the coupling agent/matrix interface. Even the amorphous cross-linked matrix nearby the filler is believed to possess properties dissimilar to those of the bulk. Each region and subregion is altered by moisture exposure to some extent; at this time studies on composite stability still focus on determining which regions are most affected by the environment an...

I. Petker

Papers

Fabrication and environmental interaction effects of filament-wound composites