Effect of polyurethane dispersion treatment on the performance improvement of carbon woven fabric-reinforced composites

In this study, two types of polyurethane dispersion were applied as surface treatment for 10 types of washed/nonwashed carbon plain woven fabric-reinforced thermosetting and thermoplastic composites. To investigate the effects of surface treatment on the mechanical properties, the impregnation of various laminates was observed by a digital microscope. Dynamic mechanical analysis (DMA) was employed to investigate the interfacial interaction properties. Static tensile test was used to study the mechanical properties of composites. A correlation between the mechanical properties and interfacial interaction of composites was successfully observed. The acoustic emission (AE) from various composites was recorded in order to investigate the initial fracture and failure mechanism. Meanwhile, the knee-point method was also employed to look for initial fracture, which showed a good fit to initial strain detected from AE (amplitude > 80 dB). Furthermore, scanning electron microscopic images of single fiber and fractured carbon fiber bundles confirmed the interfacial properties evaluated by DMA analysis. Finally, remarkable improvement in mechanical properties (≈33.3%) of CF/PA6 laminates is discussed.