A study of the effect of plasma treatment on the interfacial properties of carbon fibre–thermoplastic composites

In the present work, two different polymer matrices, polycarbonate (PC) and polyamide 6 (PA6), have been chosen, due to their different nature, amorphous and semi-crystalline, respectively, and their wide applicability: compared to bulk polymers, both polymers provide enhanced properties at moderate cost, still suitable for large-volume applications. The set of fibres used is the same as described elsewhere [5]. Fresh (untreated and unsized) high-strength, PAN-based carbon fibres (CF sample) were selected as starting material. Two different plasma treatments were performed, namely 75 W/3 min (CFP1 sample) and 150 W/3 min (CFP3). A sample of industrially oxidised but unsized carbon fibres (CFO sample) was also included. In the study, the effect of the different treatments on the tensile strength of the CF fibres, as well as the dependence of tensile strength on fibre length, has been analysed previously [5].