Synergistic effect of carbon nanoparticles on the mechanical and thermal properties of poly(lactic acid) as promising systems for packaging

Abstract

Due to the high demand of the use of food packaging in the present day, the waste from the material disposal has become a problem of high environmental impact. In this perspective, biodegradable polymers can represent a viable alternative as they degrade after their disposal, thus reducing their environmental impact. The poly(lactic acid) or polylactide is a biodegradable, biocompatible, and compostable polymer, being considered by many authors as one of the most promising biopolymers in industrial applications. However, its low thermal and mechanical properties make it an unfeasible option to replace synthetic polymers. Consequently, polymer nanocomposites containing carbon nanoparticles are products of relevant interest currently, mainly due to the thermal, mechanical, electrical, and optical properties these materials can present. Therefore, carbon nanoparticles (carbon nanotubes, graphene, and fullerene) modified with octadecylamine in their isolated state and in ternary systems in concentrations of 0.01%, 0.03%, and 0.09% were obtained from poly(lactic acid) polymer nanocomposites. After obtaining them, these systems were analyzed by TGA, DSC, FTIR, XRD, SEM, DMA, and NMR techniques. The presence of the octadecylamine modified carbon nanoparticles was able to increase the thermal and mechanical resistance of the poly(lactic acid) matrix. The systems with 0.03% of the nanostructures showed better results in both analyses. In the system with 0.09%, agglomeration occurred, and in ternary systems, the application of these particles results in a greater impact on the molecular mobility exhibiting a synergistic effect that may come from a better dispersion.

Emerging Nanoparticles in Food: Sources, Application, and Safety

“…Subsequently, CNTs are modified by carboxyl or amino groups, and the functionalized CNTs are embedded into the PLA polymers by solvent mixing or hot pressing/melt mixing. These nanostructures improve the storage modulus of the stiffness and the mechanical properties of the PLA-based materials . Adding MWCNTs to starch substrates also enhances the film water resistance, tensile strength, and hydrophobicity …”

“…These nanostructures improve the storage modulus of the stiffness and the mechanical properties of the PLA-based materials. 34 Adding MWCNTs to starch substrates also enhances the film water resistance, tensile strength, and hydrophobicity. 35 However, the requirements of modern food packaging cannot be met by only improving the mechanical properties of packaging materials.…”

Biopolymer-Based Sustainable Food Packaging Materials: Challenges, Solutions, and Applications

“…Bio-nanocomposites, which consist of a bio-based polymer matrix and an organic/inorganic filler with at least one nanoscale material, are suitable as active and/or intelligent packaging materials due to their enhanced mechanical, thermal, barrier, antimicrobial, and antioxidant properties [ 82 , 83 , 84 ]. These materials focus on extending shelf-life and reducing microbial growth in food products [ 83 , 84 ].…”

“…PLA shows incredible properties for films for food packaging applications such as mechanical strength, light transmission, transparency, rigidity, low cost, high stiffness, resilience, biodegradability, excellent barrier properties, and biocompatibility. However, it is brittle, has low melt strength, and has low thermal stability [ 9 , 62 , 84 , 98 ].…”

“…Further, the films had inhibitory effects against S. aureus . While the incorporation of modified carbon nanostructures in the PLA matrix increases the thermal and mechanical properties of the film [ 84 ]. On the other hand, the studies of Andrade-Del Olmo et al [ 178 ] focused on forming a layer-by-layer bio-nanocomposite film of PLA-ZnONPs–chitosan-β-cyclodextrins.…”