Development and Characterization of Electrospun Fiber-Based Poly(ethylene-co-vinyl Alcohol) Films of Application Interest as High-Gas-Barrier Interlayers in Food Packaging

Abstract

In the present study, poly(ethylene-co-vinyl alcohol) with 44 mol % ethylene content (EVOH44) was managed to be processed, for the first time, by electrospinning assisted by the coaxial technology of solvent jacket. In addition to this, different suspensions of cellulose nanocrystals (CNCs), with contents ranging from 0.1 to 1.0 wt %, were also electrospun to obtain hybrid bio-/non-bio nanocomposites. The resultant fiber mats were thereafter optimally annealed to promote interfiber coalescence at 145 °C, below the EVOH44 melting point, leading to continuous transparent fiber-based films. The morphological analysis revealed the successful distribution of CNCs into EVOH44 up to contents of 0.5 wt %. The incorporation of CNCs into the ethylene-vinyl alcohol copolymer caused a decrease in the crystallization and melting temperatures (TC and Tm) of about 12 and 7 °C, respectively, and also crystallinity. However, the incorporation of CNCs led to enhanced thermal stability of the copolymer matrix for a nanofiller content of 1.0 wt %. Furthermore, the incorporation of 0.1 and 0.5 wt % CNCs produced increases in the tensile modulus (E) of ca. 38% and 28%, respectively, but also yielded a reduction in the elongation at break and toughness. The oxygen barrier of the hybrid nanocomposite fiber-based films decreased with increasing the CNCs content, but they were seen to remain high barrier, especially in the low relative humidity (RH) regime, i.e., at 20% RH, showing permeability values lower than 0.6 × 10−20 m3·m·m−2·Pa−1·s−1. In general terms, an optimal balance in physical properties was found for the hybrid copolymer composite with a CNC loading of 0.1 wt %. On the overall, the present study demonstrates the potential of annealed electrospun fiber-based high-barrier polymers, with or without CNCs, to develop novel barrier interlayers to be used as food packaging constituents.

Development and Characterization of Thermoformed Bilayer Trays of Paper and Renewable Succinic Acid Derived Biopolyester Blends and Their Application to Preserve Fresh Pasta

“…This resulted in permeabilities of 1.27 × 10 −18 and 2.17 × 10 −19 m 3. m/m 2 ·Pa·s, that is, one order of magnitude lower for the petrochemical polyester when considered as a monolayer material. However, it should be noted that this commercial film is based on interlayers of EVOH, a high-oxygen-barrier copolymer in low-humidity conditions (0.77 × 10 −21 m 3. m/m 2 ·Pa·s) [ 61 ], which can be achieved in packaging structures using hydrophobic external layers (e.g., LDPE and PET) [ 63 ]. As a result, the bilayer structures presented values of permeance of 5.15 and 2.34 × 10 −15 m 3 /m 2 ·Pa·s for the paper/PBS–PBSA and paper/PET trays, respectively.…”

Pilot-Scale Processing and Functional Properties of Antifungal EVOH-Based Films Containing Methyl Anthranilate Intended for Food Packaging Applications

“…They observed a general decrease of the melting temperature, melting enthalpy and degree of crystallinity caused by the presence of the active ingredients [52]. More recently, Meléndez et al developed electrospun EVOH 44 fibres with and without cellulose nanocrystals (CNC), and they found lower T c , T m and χ c values in the samples containing CNC compared to the pristine copolymer [9].…”

“…In this line, ethylene vinyl alcohol (EVOH) copolymers are one of the best candidates used in the design and development of active materials intended for food packaging applications. EVOH copolymers, which are synthesized through the hydrolysis of ethylene vinyl acetate (EVA), are characterized by a high transparency, great chemical resistance and outstanding oxygen barrier properties [8,9]. In addition, EVOH based films are recyclable in current infrastructure by regrinding processes and several works also report that EVOH copolymers with up to 44 mol% ethylene content can be degraded in specific environmental conditions and biological media [10][11][12].…”

Dispersibility Characterization of Cellulose Nanocrystals in Polymeric-Based Composites

“…A series of parameters reflecting the mechanical properties are obtained through the stress–strain curve including Young’s modulus, tensile strength, and elongation at break. Overall, the increase in mechanical properties is attributed to the interfacial interaction between the CNC-matrix providing good stress transfer . However, the poor dispersibility of the CNC will introduce defects and stress concentration points into the matrix and weaken the cohesion of the composite.…”