Effect of µplasma modification on the wettability and the ageing behaviour of glass fibre reinforced polyamide 6 (GFPA6)

Glass fibre reinforced polyamide 6 (GFPA6) thermoplastic composites (TPCs) are promising materials with excellent properties, but due to their low surface free energy they are usually difficult to wet, and therefore, possesses poor adhesion properties. µPlasma modification offers potential solutions to this problem through functionalisation of the GFPA6 surface. In this study, the effect of µPlasma on the wetting behaviour of GFPA6 surfaces was investigated. Following single µPlasma treatment scans of GFPA6 samples, a substantial enhancement in wettability was observed. However, the effect of the µPlasma modification was subject to an ageing (hydrophobic recovery) phenomenon, although the enhancement was still partially maintained after 4 weeks. The ageing process was slower when the GFPA6 material was pre-dried and stored in low humidity conditions, thereby demonstrating the importance of the storage environment to the rate of ageing. Orientation of the fibres to the observed contact angle was found to be crucial for obtaining reproducible measurements with lower deviation. The influence of testing liquid, droplet volume and surface texture on the repeatability of the measured contact angle were also investigated.