Green Packaging Material with Enhanced Thermo–mechanical, Hermetic, and UV–shielding Properties Based on Laponite and PDA Reinforced Chitosan
摘要
For sustainable and eco-friendly packaging of various photodegradable compounds (dyes, pigments, phenols, etc.), there is a necessity to develop green packaging material. In this study, the chitosan was reinforced with laponite and polydopamine (PDA) to enhance its thermomechanical properties for UV–shielding application. Chitosan solution (S1) showed increased hydrogen–bonds as pH of the solution increased from 4 (G’ = 0.6 Pa) to 12 (G’ = 5.1 × 104 Pa) due to deprotonation of –NH3+ to –NH2 group. A slight decrease in the G’ of chitosan–PDA (S3) was observed at all pH values. The addition of laponite to S1 (S2) showed maximum G′ (1.6 × 105 Pa) at pH 10 probably due to increased electrostatic interactions between laponite and chitosan. The cumulative effect of hydrogen-bonding and electrostatic interactions led to maximum G′ (1.8 × 105 Pa) in laponite–PDA–chitosan (S4) at pH 8. Consequently, S1–S4 at pH 8 were casted into films A–D, respectively and studied using various characterization techniques. Film C showed lower swelling (896.7 ± 30.4%) and higher contact angle (55.1 ± 0.8˚) as compared to Film A. Further, the incorporation of laponite to the films, Film B and Film D, exhibited a more significant decrease in swelling (151.9 ± 13.8% and 100.2 ± 10.4%, respectively) and increase in contact angle (63 ± 0.9˚ and 66.5 ± 1.3˚, respectively). Moreover, the degradation of Rhodamine B (RhB) over a period of 240 min in the presence of films was evaluated to assess the UV shielding properties of the films. It was observed that film D showed lowest RhB degradation (19.6%) as compared to unshielded RhB (70.03%).