Reusing uncured Fiber-reinforced thermoset composite Prepreg waste with water-soluble PVA backing film

One challenge in reusing uncured composite prepreg waste is the removal of the backing film. Ensuring that no backing film remains during the reuse of composite prepreg material is crucial, as the presence of backing film in the laminate can contaminate the part, leading to defects such as delamination. Manual removal of the backing film from the leftover uncured composite prepreg is a labor-intensive task, and ensuring there is no remaining backing film in the prepreg waste can be challenging. To address these issues, the authors implemented a water-soluble polyvinyl alcohol (PVA) film as the backing material for the prepreg, allowing less labor-intensive removal of the PVA backing film by soaking the prepreg in water before reusing. In this study, 20 μm thick 100% PVA film was utilized as backing material for carbon fiber-reinforced thermoset composite prepreg. The performance of the PVA film as a prepreg backing material was assessed, and the process of removing the backing film was demonstrated. To investigate the impact of the backing film removal process on the mechanical properties of the reused prepreg, tensile and double cantilever beam (DCB) tests were conducted. The results indicated that the PVA backing removal and drying processes did not show any significant influence on the tensile properties and interlaminar strength of the reused composite prepreg. Furthermore, this study demonstrated the recycling of the PVA solution used in the backing removal process to produce new PVA film. The application of PVA as a backing film not only simplified the backing film removal for reused prepreg but also established a sustainable closed-loop recycling system for prepreg backing film.