Facile approach for synthesis of glutaraldehyde cross-linked PVA films using layered double hydroxide as fillers for food-packaging applications

The application of poly (vinyl alcohol) films in food packaging industries is limited due to its inherent disadvantage of poor water resistance property because of its alcohol (-OH) groups. In this study, poly (vinyl alcohol) (PVA) films were modified by using glutaraldehyde (GA) as crosslinker to reduce the water uptake capacity. Layered double hydroxide (LDH) intercalated with para-hydroxybenzoic acid was used as a filler in the polymer matrix to improve the properties of the composite films (P-G-L (PVA-GA-LDH) composite). Influence of the additive and crosslinking on the polymeric films were analyzed by XRD, FTIR, TGA, SEM etc. Presence of the acetal group i.e. -O-CH₂-O- in FTIR after crosslinking confirms the development of crosslinking and the corresponding swelling degree of P-G-L composite is 1.67 %. The composite film has >91 % degree of crosslinking with a water contact angle of 88°. The free radical scavenging activity of the aforementioned composite (P-G-L (2 %)) is 67 % against DPPH in 48 h. Also, P-G-L (2 %) composite film has 84.5 % light transmittance whereas the film without any filler shows 91 % transmittance. Additionally, the composite film depicted >95 % of antibacterial activity against both E.coli and S. aureus (which is a promising finding when compared to the existing literatures) as a result of slow and sustained release of the para-hydroxybenzoate to the medium. All the above mentioned characteristics hints for the possible use of the P-G-L composite film as a packaging material.