An investigation of the influence of matrix properties and fibre–matrix interface behaviour on the mechanical performance of carbon fibre-reinforced PEKK and PEEK composites. (February 2023)

• Record Type: Journal Article
• Authors: Ramaswamy, Karthik; Modi, Vedant; Rao, Pavan S.; Martin, Pedro P.; McCarthy, Conor T.; O'Higgins, Ronan M.
• Is Part Of: Composites. Volume 165(2023)
• Publication Date: 2023-02
• Subjects: Carbon-fibre -- Poly-ether-ether-ketone (PEEK) -- Poly-ether-ketone-ketone (PEKK) -- Crystallinity -- Fibre-matrix adhesion -- In-plane tests -- Interlaminar tests -- Fractography analysis; Composite materials -- Periodicals; Manufacturing processes -- Periodicals; Composite materials; Manufacturing processes; Periodicals; 620.11805
• DOI: 10.1016/j.compositesa.2022.107359
• Languages: English
• ISSNs: 1359-835X

Abstract

Abstract: Poly-ether-ketone-ketone (PEKK) is an emerging alternative to poly-ether-ether-ketone (PEEK) as a matrix for high-performance carbon fibre (CF) reinforced composites. Herein, the results of an experimental investigation to examine the influence of matrix properties and fibre–matrix interface behaviour on the mechanical performances of CF/PEKK and CF/PEEK composites are presented. CF/PEKK presents superior strength under longitudinal tension, longitudinal and transverse compression, as well as in-plane shear. It also exhibits better interfacial shear strength (IFSS) than CF/PEEK, which contributes to its superior strength, as damage typically initiates at the fibre–matrix interface under in-plane loading. Predictions of different analytical models adopted from the literature, which assess the influence of fibre–matrix adhesion on the in-plane strength, compare favourably to the experiments. Under cyclic shear tests, CF/PEKK exhibited more gradual stiffness reductions and low shear plasticity until 5% shear strain, indicating a more damage tolerant matrix. Relative to CF/PEEK, CF/PEKK presents superior interlaminar shear strength (ILSS) and mode I fracture toughness (GIC ), but similar mode II fracture toughness (GIIC ). High GIC is due to a synergistic interaction between its inherently ductile matrix and high IFSS, while ILSS strongly correlates with IFSS. Overall, CF/PEKK offers a better combination of strength and toughness, exceeding CF/PEEK.