Study of the carbon fiber–poly(ether–ether–ketone) (PEEK) interfaces, 1: surface characterization of fibers and matrices, and interfacial adhesion energy

Abstract

The aim of this general study is to determine the physicochemical characteristics and mechanical properties of carbon fiber–PEEK interfaces. In the first part, the dispersive component of the surface energy and the electron acceptor–donor (acid–base) characteristics of PEEK polymer and different types of untreated and surface‐treated carbon fibers are determined by means of inverse gas–solid chromatography at infinite dilution. It appears, in particular, that the acid–base surface properties of PEEK and, consequently, the orientation of macromolecules near the surface, depend on the processing of this polymer. Moreover, according to previous work, an estimation of the adhesion energy, corresponding to physical interactions (London and acid–base interactions) at carbon fiber–PEEK interfaces is proposed. Whatever the surface characteristics of PEEK, the highest level of carbon fiber–PEEK adhesion is achieved in systems involving oxidized or sized carbon fibers.

Study of the carbon fiber–Poly(Ether–Ether–Ketone) (PEEK) interfaces, 3: influence and properties of interphases

“…As already stated [5] for PEEK polymer, this temperature could be located anywhere between the onset of the crystallization and the glass transition temperature. To a first approximation, and in agreement with Vautey et al [4], the relative contraction E , of the carbon fiber at a given temperature T is equal to: E, = alA Tl + azA T2 (1) where al (=47 x lo-(' K-I) and az(==108 x K-') are the thermal expansion coefficients of PEEK, below and above its glass transition temperature T,(=143OC) respectively. In equation (l), AT1 and AT, are, respectively, equal to (T-T,) and (T, -SFT);…”

Enhancing the Interfacial Strength of Carbon Fiber/Poly(ether ether ketone) Hybrid Composites by Plasma Treatments

“…The resulting mechanical properties of CF/PEEK depend mainly on the interfacial property, which plays an important role in stress transfer between the reinforcement and the matrix [8,9,10]. The physical state and chemical structure of CFs and PEEK fiber determine the interfacial strength [11]. Hence, the low interfacial bonding strength between CF and PEEK fiber matrices due to the intrinsically smooth, hydrophobic, and chemically inert CF surface is a problem that must be addressed.…”

Mechanisms of formation and properties of interphases in polymer based multicomponent materials

“…The first one concerns the formation of a "transcrystalline" interfacial layer in a carbon fibre -PEEK system (8). The creation of such an interphase depends strongly on the level of fibre-matrix interaction and processing parameters, mainly the rate of crystallisation.…”