Mode I Fracture Toughness Behaviour of Recyclable Piezoelectric Composites

The primary objective of this study was to focus on structural health monitoring of fibre reinforced recyclable composites, while also aiming to achieve high mechanical performance. To achieve this goal, unidirectional carbon fibre-reinforced piezoelectric composites were fabricated using a vacuum-assisted resin infusion technique. The composite structure consisted of carbon fibres, a recyclable thermoplastic resin, and a Polyvinylidene fluoride (PVDF)-Multiwalled carbon nanotubes (MWCNTs)- Polyphenylene sulfide (PPS) layer. This layer was designed to improve β phase content of PVDF by adding 0.2 wt.% MWCNTs to a 20 wt.% PVDF solution, which was then impregnated into the PPS veil. The PVDF solution-impregnated PPS veil was perforated, and mechanical results of the composites were compared with those of composites that included non-perforated layer. FTIR and XRD techniques were used to analyse the chemical and crystalline structure of PVDF-MWCNTs-PPS veils, resulting in 77 % β+.Ñó. polar phases that generated a 100 mV voltage output. The newly developed composites were also subjected to mechanical analysis, including 3-point bending test, interlaminar shear strength and mode I fracture toughness test. It was found that perforation of the PVDF layer enhanced resin infusion, resulting in improved performance in mode I fracture toughness and increased flexural properties compared to non-perforated ones. This study could potentially have a significant impact on industries that rely-on fibre-reinforced composites. By using recyclable piezoelectric composites, the industries could benefit from significant cost savings in maintenance and repair, while also contributing to a greener future.