Photophysical, and mechanical properties of fruit juice extract-incorporated PVA biocomposites

Natural pigment-rich extract offers a route to modify the optical properties of the polymer. In this study, polyvinyl alcohol (PVA) was incorporated with varying concentrations of fruit juice extract like pomegranate (PE), dragon fruit (DE), and black grapes (BE), to investigate their structural, optical, and mechanical property. XRD and SEM analyses revealed that the addition of extracts disrupted the crystalline order of PVA, leading to enhanced amorphous characteristics and surface heterogeneity. The FTIR results show the changes in the O–H band due to the hydrogen bonding between PVA and the extract components. UV-visible spectroscopy confirmed strong absorption in the 250–600 nm region, with increasing absorbance intensity at higher extract concentration, suggesting the improved electronic disorder and charge transfer. Photoluminescence spectra exhibited excitation-dependent emission with concentration dependent intensity variation, while decreased PL-QY and lifetime suggesting aggregation-induced quenching and enhance non-radiative recombination. Mechanical properties depended on extract type and concentration, PE/PVA at 4.0 v/v% exceeded the strength of pristine PVA, while moderate loadings increased stiffness and elongation and higher loadings reduced flexibility, consistent with plasticization and phase separation. The optimized PE/PVA (8.0 v/v%), DE/PVA (2.0 v/v%), and BE/PVA (10.0 v/v%) composites showed balanced mechanical and optical responsiveness. These results show how extract type and concentration tune the structural, mechanical, optical, and PL quenching behaviour of PVA polymer.