Paper number 218

INFLUENCE OF TRANSCRYSTALLINE INTERPHASE ON FLEXURAL FAILURE OF SHORT CARBON FIBER REINFORCED PEEK COMPOSITES

Chi-Cherng Jeng and Ming Chen

Institute of Materials Science and Engineering, National Sun Yat-Sen University
Kaohsiung, Taiwan 80424, R.O.C.

Summary

Two kinds of short carbon fiber reinforced poly(ether ether ketone) composites were prepared with and without transcrystalline interphase. The fiber length distribution, fiber orientation and crystallinity were all carefully characterized. These composites with thickness of 3 mm and span-to-thickness ratio of 32 were subjected to three-point-bending test at speeds of 0.5, 5, and 50 mm/min. The transcrystalline interphase enhanced the fiber-matrix adhesion, improved the flexural deflection and strength of the composite. The fractography was examined by means of scanning electron microscope. The appearance of load-deflection curves and the fractography suggest that the compressive crack occurred first; the stress concentration under the loading nose and the shear stress maximum induced the upper shear cracks which blunted the propagation of compressive crack. Then the tension crack initiated from the tension side, met with the lower shear crack near the core region, and resulted in a catastrophic failure.

Keywords

peek, injection molding, transcrystalline, flexure, failure mode.