Mechanical, UV protection, and antibacterial properties of poly(vinyl alcohol) /marine mucilage biocomposite films

Abstract The mucilage that accumulated in the Sea of Marmara in 2021 turned into an environmental disaster that threatened not only marine life but also the shipping and tourism industries. However, because of the partially organic structure of marine mucilage, it has the potential to be used as an additive for polymer films. In this study, bioplastic films were prepared from PVA with a series of mucilage content from 0% to 50% by mass, and their properties were investigated. The FT‐IR spectra revealed a shift in hydroxyl peaks, suggesting an interaction between the mucilage and PVA. SEM images showed the formation of crystal forms at the higher mucilage content of 20%, indicating ionic saturation of the PVA matrix. EDX and XRD analyses revealed that the crystal was NaCl coming from the mucilage composition. The tensile strength of the neat PVA film was measured as 9.86 MPa and improved to 14.56 MPa with 5% mucilage content, which is attributed to the ionic cross‐linking. The tensile properties were preserved up to 20% of the mucilage content, and then sudden decrements were observed. The transmittance percentage ( T %) of the neat PVA film in UV–Vis spectra (800–200 nm) was detected as 75% at 500 nm and decreased down to 39% with increased mucilage content up to 50%. Furthermore, a rising limit of linearity (LOL) of the spectrums was observed from 350 to 580 nm, with increasing mucilage content from 5% to 50%. The biofilms showed antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. Hence, a robust and biodegradable film having UV protection and antibacterial activity was developed from the marine mucilage bio‐waste. Highlights Poly(vinyl alcohol)/marine mucilage biocomposite films were prepared. Biocomposite films showed increased UV‐A, UV‐B, and UV‐C protection with increased mucilage content. Enhanced tensile strength of biocomposite films up to 20 wt% mucilage content was determined due to ionic crosslink formed by NaCl salt ions. Biocomposite exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus .