Fabrication and Characterization of Poly (Vinyl Alcohol) Biofilms Reinforced With Alkali‐Treated Sapindus mukorossi Shell Filler

Polymer films composed of biodegradable polymers containing lignocellulosic fillers have been identified as good candidates for substitution for conventional petroleum‐derived packaging materials. In the current study, polyvinyl alcohol (PVA) biofilms containing 5–25 wt% alkali‐treated Sapindus mukorossi shell filler (at. SMSF) were synthesized through the solution casting method. The objective of this study is to explore the structure of PVA biofilms, thermal behavior, mechanical behavior, optical, surface, and antibacterial properties. The removal of amorphous parts through alkali treatment exposed cellulose‐filled microfibrils, resulting in the development of strong intermolecular hydrogen bonds with the PVA matrix. FTIR showed improvement in interfacial compatibility without the creation of any new chemical bond. On the other hand, XRD analysis depicted an increase in crystallinity from 32.5% to 54.8% and crystallite size from 18.2 to 31.3 nm. Thermal analysis proved that the biofilms exhibited good thermal stability and high degradation temperatures, along with a reduction in heat flow and an increase in char formation. SEM and surface roughness analysis depicted uniform dispersion of fillers and compact morphology, especially in the case of medium loading of fillers. There was significant enhancement in mechanical properties, where tensile strength and Young's modulus increased from 23.5 to 46.8 MPa and from 29.5 to 62.3 MPa, respectively. The contact angle of water increased from 51.3° to 92.5°, showing remarkable improvement in water repellence. Moreover, PVA/25 wt% at. SMSF showed significant UV‐blocking efficiency and very good antibacterial properties toward Escherichia coli and Bacillus cereus . The results showed that alkaline‐treated SMSF can be a very good bio‐component to develop mechanically tough, thermally stable, moisture‐resistant, and antibacterial PVA biofilm for use as a packaging material.