The use of discontinuous PEEK/carbon fiber thermoplastic moulding compounds for thick-section componentry

Abstract

The hot-pressing of discontinuous fiber moulding compounds (DFMCs) is an established way of forming geometrically complex components, however, it is not a simple process. Rapid and irreversible cure cycles hinder the use of thermoset resins, and thermoplastic resins offer inferior mechanical performance. The recent availability of DFMCs utilising a Polyether Ether Ketone (PEEK) matrix offer an alternative, combining the usability of thermoplastics with significantly enhanced mechanical properties. A novel manufacturing approach is proposed and investigated, in which virgin material is consolidated into multiple 'pre-charges' prior to pressing the final component, combating the limitations of DFMCs; loft, voidage and fiber orientation. Short beam shear tests were employed to assess the mechanical implications of laminating DFMCs, demonstrating minimal differences to a standard sample. Three-point bend tests assessed rudimentary orientation of fiber bundles, showing significantly improved mechanical performance at the cost of toughness. A novel method to determine the interlaminar shear modulus is also presented and successfully validated.

Effect of carbon fiber inclusions on polymeric transfer film formation on steel

“…While fillers with high aspect ratio, such as carbon fiber, carbon nanotubes, carbon nanofiber, and glass fiber, primarily increase the mechanical properties by increasing the load bearing capacity; adding carbonaceous material in the form of particles or fibers to polymers also improve thermal and electrical properties of the composites [10]. Their effect on the tribological performance of PEEK has been reported for various CF concentrations, pressure (loads) [11,12] and orientation [13][14][15][16][17]. In general, the study on the effect of fiber orientation using long fibers have concluded that polymer composites with fiber's long axis orientation normal to the sliding surface show the best performance followed by those in where fibers are aligned lengthwise to the sliding direction 4 [18].…”