Sandwich-Architectured Poly(lactic acid)–Graphene Composite Food Packaging Films

Abstract

Biodegradable food packaging promises a more sustainable future. Among the many different biopolymers used, poly(lactic acid) (PLA) possesses the good mechanical property and cost-effectiveness necessary of a biodegradable food packaging. However, PLA food packaging suffers from poor water vapor and oxygen barrier properties compared to many petroleum-derived ones. A key challenge is, therefore, to simultaneously enhance both the water vapor and oxygen barrier properties of the PLA food packaging. To address this issue, we design a sandwich-architectured PLA-graphene composite film, which utilizes an impermeable reduced graphene oxide (rGO) as the core barrier and commercial PLA films as the outer protective encapsulation. The synergy between the barrier and the protective encapsulation results in a significant 87.6% reduction in the water vapor permeability. At the same time, the oxygen permeability is reduced by two orders of magnitude when evaluated under both dry and humid conditions. The excellent barrier properties can be attributed to the compact lamellar microstructure and the hydrophobicity of the rGO core barrier. Mechanistic analysis shows that the large rGO lateral dimension and the small interlayer spacing between the rGO sheets have created an extensive and tortuous diffusion pathway, which is up to 1450-times the thickness of the rGO barrier. In addition, the sandwiched architecture has imbued the PLA-rGO composite film with good processability, which increases the manageability of the film and its competency to be tailored. Simulations using the PLA-rGO composite food packaging film for edible oil and potato chips also exhibit at least eight-fold extension in the shelf life of these oxygen and moisture sensitive food products. Overall, these qualities have demonstrated the high potential of a sandwich-architectured PLA-graphene composite film for food packaging applications.

Enzymatic degradation, electronic, and thermal properties of graphite‐ and graphene oxide‐filled biodegradable polylactide/poly(ε‐caprolactone) blend composites

“…These conventional materials include nondegradable polymers, expensive metals, and ceramics at large . In this rational, there is imminent environmental challenges brought by wastes of metals and plastic related materials which is increasing due to the short lifetime of nondegradable material applications . Therefore, the use of environmentally friendly polymers and their composites with tailored properties is expanding .…”

Development and characterisation of polylactic acid–gliadin bilayer/trilayer films as carriers of thymol

“…Furthermore, it is 'generally recognized as safe (GRAS)' as food packaging materials (Ramot et al, 2016). PLA film exhibits good mechanical and physical properties, which are comparable to petroleum-derived polymers such as polystyrene (PS) and polyethylene terephthalate (PET) (Goh et al, 2016). Nonetheless, the intrinsic barrier properties of PLA are viewed as a stumbling block and need to be addressed to make it competitive with petroleum-derived polymers (Goh et al, 2016).…”

α-methylstyrene-assisted maleic anhydride grafted poly(lactic acid) as an effective compatibilizer affecting properties of microcrystalline cellulose/poly(lactic acid) composites

“…PLA is a fully biodegradable thermoplastic polymer that is produced by the fermentation of maize, wheat, straw, or other plant resources followed by posterior ringopening polymerization [7,8]. PLA offers several advantages, such as high strength, high stiffness, and biocompatibility, allowing its widespread use in textiles, packaging, and medical and automotive fields [9][10][11][12][13]. However, PLA has several drawbacks that limit its application, including high brittleness, relatively high price, and processing instability [14].…”