Ultra-violet light-driven green oxygen scavenging composite made of PVA/NRL for active packaging: an alternative to metallic oxygen scavengers

Abstract

Active packaging techniques such as oxygen scavenging have gained much attention from consumers in the past few years. It would be of great advantage if metal-based scavengers were replaced with plant-based sustainable and biodegradable materials. In this work, plant-based natural rubber latex was explored as a potential oxygen-scavenging material in combination with polyvinyl alcohol (PVA) to fabricate potentially biodegradable films. PVA and NRL were taken in different ratios for film formation and analyzed for their physical, mechanical, thermal, and moisture barrier properties along with their biodegradability as well as oxygen scavenging capacity and rate. Apparently, the film with two parts of NRL exhibited the highest scavenging capacity with a rate of 1045 mL O₂ per g and 95 mL O₂ per g per day at 60 °C and 120 s of UV-C exposure time, respectively, and a water contact angle of 65.18°. Alternatively, the same film has the lowest tensile strength of 10.36 MPa and did not degrade even after 90 days. The addition of two parts of PVA yielded the highest tensile strength of 24.32 MPa and faster degradation in 60 days. A higher water transmission rate of 24.2 g per m² per day was seen in the film with equal parts of PVA and NRL. After oxidation, all the films showed a significant color change compared to the color before oxidation. The films turned light brown from pale yellow and had the highest total color change of 31.27. This change in color can be a visual indication of oxygen scavenging by NRL. These results suggest that the fabricated potentially biodegradable PVA and NRL composite films can effectively scavenge oxygen with good mechanical and barrier properties and can hence be used in food packaging.