Crosslinked poly (vinyl alcohol): Structural, optical and mechanical properties

Abstract

Poly (vinyl alcohol) (PVA) is a water-soluble, transparent, semi-crystalline polymer with excellent mechanical properties, chemical resistance, and biocompatibility. The crystallinity, optical and mechanical properties of PVA can be modified by the crosslinking process. In this work, a simple heat treatment method is used to fulfil this purpose. Prepared films are heated at different temperatures and time intervals, and their various properties were studied. Due to heating, PVA becomes more crystalline, and as a result, some weak peaks become more pronounced in X-ray diffraction data. Fourier transform infrared studies are incorporated to show structural modification and the presence of covalent bonds. Smooth surface morphology of PVA films is obtained from scanning electron microscopy images, except for the film treated at a higher temperature. Optical properties of pure and heat-treated films are explored using UV-Vis absorption and photoluminescence spectroscopy. UV-Vis absorption peaks of pure PVA are located at around 284 nm and 325 nm, and the corresponding fluorescence emission is observed at around 416 nm. From all the experimental observations, an improved crosslinked structure is obtained for the film heated at 140°C for 40 min. In this condition, the improved mechanical property is also obtained from the stress-strain curves. This crosslinked PVA prepared by simple heat treatment can have potential applications in the textile industry, food packaging, etc.