Effect of glycidyl methacrylate-grafted poly(ethylene octene) on the compatibility in PLA/PBAT blends and films

A reactive compatibilization with the compound containing four epoxy groups for polylactic acid/poly(butylene adipate-co-terephthalate)/thermoplastic starch ternary bio-composites

How to effectively improve the poor interfacial adhesion between polylactic acid/poly(butylene adipate-co-terephthalate) (PLA/PBAT) matrix and thermoplastic starch (TPS) is still a challenge. Therefore, this work aims to introduce a convenient method to enhance the performance of PLA/PBAT/TPS blend by melt reactive extrusion. Here, using 4,4'-methylene-bis(N,N-diglycidyl-aniline) (MBDG) containing four epoxy groups as a reactive compatibilizer, and respectively using 1-methylimidazole (MI) or triethylenediamine (TD) as a catalyzer, serial PLA/PBAT/TPS ternary bio-composites are successfully prepared via melt reactive extrusion. The results showed that, under the catalysis of organic base, especially MI, the epoxy groups of MBDG can effectively react with hydroxyl and carboxyl groups of PLA/PBAT and hydroxyl groups in TPS to form chain-expanded and cross-linked structures. The tensile strength of the composites is increased by 20.0 % from 21.1 MPa, and the elongation at break is increased by 182.4 % from 17.6 % owing to the chain extension and the forming of cross-linked structures. The molecular weight, thermal stability, crystallinity, and surface hydrophobicity of the materials are gradually improved with the increase of MBDG content. The melt fluidity of the composites is also improved due to the enhancement of compatibility. The obtained PLA/PBAT/TPS materials have the potential to be green plastic products with good properties.

Synergistic effect of graphene oxide/zinc oxide nanocomposites on polylactic acid-based active packaging film: Properties, release kinetics and antimicrobial efficiency

Incorporating two different nanoparticles in nanocomposite films is promising as their synergistic effects could significantly enhance polymer performance. Our previous work conferred the remarkable antimicrobial (AM) properties of the polylactic acid (PLA)-based film using optimal formulations of synergistic graphene oxide (GO)/zinc oxide (ZnO) nanocomposites. This study further explores the release profile of GO/ZnO nanocomposite and their impact on the antimicrobial properties. A fixed 1.11 wt% GO and different ZnO concentrations were well dispersed in the PLA matrix. Increasing ZnO concentrations tended to increase agglomeration, as evident in rougher surfaces. Agglomeration inhibited water penetration, leading to a significant reduction in water permeability (46.3 %), moisture content (31.6 %) but an improvement in Young's Modulus (52.6 %). The overall and specific migration of GO/ZnO nanocomposites was found to be within acceptable limits. It is inferred that the release of Zn2+ ions followed pseudo-Fickian behavior with an initial burst effect. AM film with the highest concentration of ZnO (1.25 wt%) exhibited the highest inhibition rate against Escherichia coli (68.0 %), Bacillus cereus (66.5 %), Saccharomyces cerevisiae (70.9 %). Results suggest that GO/ZnO nanocomposites with optimal ZnO concentrations have the potential to serve as promising antimicrobial food packaging materials, offering enhanced barrier, antimicrobial properties and a controlled release system.