Mechanical properties and morphology of different carbon fiber lengths in reinforced polyetheretherketone(PEEK) composites

Long discontinuous aligned carbon fiber reinforced polyetheretherketone (PEEK) composites with fiber lengths of 2, 3, 4, and 5 cm were prepared by a novel process. The fiber alignment in the composite increased with the increasing fiber length. Over 83 percent and 69 percent of fibers are oriented within +/- 5 degrees for the composites reinforced with 5 cm and 2 cm fibers, respectively. On the other hand, only 15 percent fibers are oriented within +/- 5 degrees in short fiber reinforced composites with the average length of 0.09 mm. The tensile strength of the composites reinforced with 5 cm fiber was over 60 percent of the tensile strength of the continuous fiber reinforced composites, and the flexural strength and modulus can reach as high as 85 percent of those values for the continuous fiber reinforced composites. Moreover, these properties are much higher than those of the short fiber reinforced composites containing 24.4 vol% fiber.