Effect of cross-linking and reinforcement on mechanical and thermal properties of PVA-based functionalised graphene-reinforced composite film

Graphene is a highly versatile and multifunctional 2-D atomic carbon nanomaterial with impressive mechanical properties, a unique combination of thermal and electrical conductivity, and a high surface area. On the other hand, polyvinyl alcohol (PVA) is a synthetic biodegradable polymer with moderate mechanical properties. The primary objective of this research work is to enhance the moisture absorption, solubility, mechanical, and thermal properties of PVA using a cross-linking agent and to optimize the parameters that influence the cross-linking process. Sustainable cross-linking enhances the solubility issue of neat PVA and reduces its hydrophilicity. To make it suitable as reinforcement with a polymer matrix, functionalization of graphene powder is required to decrease its inertness. The use of functionalized graphene as reinforcement resulted in improved mechanical performance when compared to PVA and cross-linked PVA films, and 1.5 wt% of f-graphene was discovered to be the optimal particle weight percentage, resulting in the highest value of UTS at 103.84 MPa. The strength of the composite increased by 192.7% compared to the UTS of PVA, which was 35.47 MPa. Biodegradability test results showed that the film with 0.5 wt% of f-graphene had the maximum biodegradability of 20.4%, while the film with 1.5 wt% of f-graphene had the minimum biodegradability of 5.3% due to a reduction in crystallinity caused by a dense and cross-linked microstructure. DMA analysis was performed to determine the glass transition temperature of the composite films. TGA analysis demonstrated that the thermal stability of the composite films had been enhanced, and the degradation of the matrix chain was gradual for composite films, unlike PVA.