Fatigue-Creep Interaction on Fatigue Crack Propagation Property of Recycled Advanced-Reinforced PEEK at Elevated Temperature

The influences of interaction between fatigue and creep have been studied for fiber-reinforced-PEEK (poly-ether-ether-keton) materials at elevated temperature. Especially, the mechanism of complex deterioration by heat, stress and recycling process has been analyzed. Main results were as follows : (1) The resistance of crack propagation of recycled carbon-fiber-reinforced PEEK (CF material) was equal to that of the virgin material, on the other hand, the resistance of recycled glass-fiber-reinforced PEEK was lower than that of the virgin material. (2) Strain at notch tip increased remarkebly with increasing number of cycles in fatigue process at elevated temperature. It was thought that the creep velocity was increased by decreasing of the elasticity modulus of PEEK matrix at the ultimate environmental temperature above glass transition temperature. (3) It was found that the carbon fibers were not broken by recycling process, but the glass fibers were broken by recycling process. So it was understood that the difference of resistance against fatigue crack propagation and creep due to kinds of reinforced fiber can be explained by the difference of fiber bridging effect. (4) It was suggested that the reliability of recycled plastic products would be improved by the control of meso-scopic factor.