Implementation of High Gas Barrier Laminated Films Based on Cellulose Nanocrystals for Food Flexible Packaging

Abstract

In this work, three types of cellulose nanocrystals (CNCs) were used: CNCSO3H extracted from wood pulp by sulfuric acid (H2SO4), CNCCOOH extracted from cotton linters by ammonium persulfate (APS) and CNCCOOR obtained by esterification of the previous two CNCCOOH and CNCSO3H. For a comparative assessment of gas barrier performance, plastic films such as PLA, PET, PE, PP, OPP and OPA were selected, coated with the three types of CNCs and finally laminated with a solvent-based polyurethanic adhesive. First, all dispersed CNCs were characterized by apparent hydrodynamic diameter and Z potential by means of dynamic light scattering (DLS) and electrophoretic light scattering (ELS) techniques, respectively, followed by the crystallinity index (XRD), thermogravimetric analysis (TGA) and evaluation of Fourier-transform infrared spectroscopy (FTIR), as well as the charges density. The surface chemistry of coated plastics (CNCs-P) was assessed by the Z potential through the electrokinetic technique (streaming potential method) and the optical contact angle (OCA). Lastly, laminated films (P-CNC-P) were evaluated by gas permeability measurements at 23 °C and 50–80% RH. It is worth noting that improvements between 90% and 100% of oxygen barrier were achieved after the lamination. This paper provides insights on the choice of cellulosic nanomaterials for the design and development of advanced and sustainable food packaging materials.

The Synthesis Methodology of PEGylated Fe3O4@Ag Nanoparticles Supported by Their Physicochemical Evaluation

“…Nanotechnology is a field dealing with the synthesis of various structures having at least a size within the range 1–100 nm and is one of the most rapidly developing sciences [ 1 ]. Nanomaterials find applications in such areas as food packaging [ 2 ], the electric industry [ 3 , 4 ], or catalysts [ 5 , 6 ]. Nonetheless, particular interest in nano-sized materials is currently observed in medicine and the related areas, i.e., in orthopedy [ 7 ], dentistry [ 8 , 9 ], or in drug delivery [ 10 , 11 , 12 ].…”

Manufacturing of Food Packaging Based on Nanocellulose: Current Advances and Challenges

“…In another study, similar strategy has been adopted for an immediate and swift application of the nanocellulose in packaging even in higher RH (50-80%) by resorting to lamination. As a result, the oxygen permeability performed on the laminates based on CNCs coatings was null at 80% RH [38].…”

“…More recently, an in situ esterification was successfully performed by crystals interaction containing hydroxyl and carboxylate groups present on their surface. Several plastic films were coated with those esterified CNCs, resulting in significant improvement in oxygen barrier at 50% and 80% RH [38]. Esterified CNFs was also produced by the succinic anhydride esterification, yielding a better thermal stability and higher transparency compared to the neat one [39].…”

“…show lower viscosity compared with uncharged CNCs (HCl). For coating deposition, the concentration between 6 and 8 wt% of CNCs slurry has been adopted in many works [38,78]. As a rule of thumb, a lower concentration requires several CNCs layers until it reaches the necessary thickness for a complete coverage of the material, whereas a much higher concentration causes the brittleness of the CNCs coating after drying.…”

“…Coating techniques such as bar/rod coating, size press, and spray have been widely used to coat the nanocellulose suspension even in multilayer structures. Actually, a bar coating deposit weigh of 1 g/m 2 of the CNCs in a single layer application and a thickness of 1 µm were employed [38]. It was also reported that for bar coating, the number of layers is proportionally linked to the thickness.…”