Solvent Assisted Delamination Crack Growth Behavior of Amorphous Thermoplastic Materials
ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB
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Crack growth studies are being carried out with oxylene in an amorphous thermoplastic, polyetherimide PEI, via a static deadweight loading apparatus. The three systems evaluated were the neat resin, composite, and adhesively bonded composite. The neat resin specimens show striation-like crack growth band markings on the fracture surfaces. The spacing between the growth bands increases with increasing crack length in each specimen. In the case of the adhesively bonded composite, a characteristic mosaic pattern of intersecting cracks normal to the plane of the adhesive was seen on the fracture surfaces. There cracks, as well as matrix cracks perpendicular to the fibers seen on the fractured composite specimens, appear to result from residual stress driven solvent cracking. Although the rates of crack propagation in the composite systems are much slower than those in the neat resin at most GI values, the mode of solvent-induced degradation is shown to be matrix dominated. Keywords Environmental tests Delamination Toughness.
- Laminates and Composite Materials