Transparent bionanocomposite films based on chitosan and TEMPO-oxidized cellulose nanofibers with enhanced mechanical and barrier properties

Abstract

The development of biobased active films for use in food packaging is increasing due to low cost, environmental appeal, renewability and availability. The objective of this research was to develop an effective and complete green approach for the production of bionanocomposite films with enhanced mechanical and barrier properties. This was accomplished by incorporating TEMPO-oxidized cellulose nanofibers (2,2,6,6-tetramethylpiperidine-1-oxyl radical) into a chitosan matrix. An aqueous suspension of chitosan (100-75wt%), sorbitol (25wt%) and TEMPO-oxidized cellulose nanofibers (TEMPO-CNFs, 0-25wt%) were cast in an oven at 40°C for 2-4days. Films were preconditioned at 25°C and 50% RH for characterization. The surface morphology of the films was revealed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thermal properties and crystal structure of the films were evaluated by thermogravimetric analysis (TGA-DTG) and X-ray diffraction (XRD). Incorporation of TEMPO-CNFs enhanced the mechanical strength of the films due to the high aspect ratio (3-20nm width, and 10-100nm length) of TEMPO-CNFs and strong interactions with the chitosan matrix. Oxygen and water vapor transmission rates for films that are prepared with chitosan and TEMPO-CNFs (15-25wt%) were significantly reduced. Furthermore, these bionanocomposite films had good thermal stability. Use of TEMPO-CNFs in this method makes it possible to produce bionanocomposite films that are flexible, transparent, and thus have potential in food packaging applications.

Fabrication Flexible and Luminescent Nanofibrillated Cellulose Films with Modified SrAl2O4: Eu, Dy Phosphors via Nanoscale Silica and Aminosilane

“…This can be attributed to the gradual weakening of the cellulose network with an increase in the phosphor amount. Similar results have been reported for other ONFC films [31]. The tensile stress of the 1/1 (ONFC/phosphor) composite film was 64.2 MPa, and the Young’s modulus decreased only by 24.16% from 3850 to 2920 MPa.…”

“…However, the uncoated phosphors did not exhibit any afterglow luminescence in the dark compared with the modified particles, which can be attributed to the formation of alumina floccus because of the hydrolysis of SrAl 2 O 4 in water [18]. While the modified particles formed uniform suspensions in the ONFC matrix this was mainly attributed to the formation of hydrogen bonds between the nanocellulose and the SiO 2 @SAOED particles and additional electrostatic adsorptions for the NH 2 @SiO 2 @SAOED and nanocellulose by an opposite charge [31,32]. The presence of a sufficient amount of nanocellulose and their small size ensured the stability of the mixed suspensions.…”

“…Comparing with other nanocelluloses, TEMPO-oxidized nanofibrillated cellulose (ONFC) was prepared by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation method [30]. It is stable in homogeneous suspensions with rich surface carboxylation and has some additionally distinct characters [31], especially smaller size, higher surface chemical activity, stability of the suspension, and higher light transmittance. Hydrogen bonds and electrostatic attraction between the negatively charged carboxylate groups (–COO − ) of ONFC and the positively charged ammonium groups (–NH 3 + ) of the modified phosphors may be the driving forces for a better interface combination [31,32].…”

“…It is stable in homogeneous suspensions with rich surface carboxylation and has some additionally distinct characters [31], especially smaller size, higher surface chemical activity, stability of the suspension, and higher light transmittance. Hydrogen bonds and electrostatic attraction between the negatively charged carboxylate groups (–COO − ) of ONFC and the positively charged ammonium groups (–NH 3 + ) of the modified phosphors may be the driving forces for a better interface combination [31,32]. Therefore, these strong bonds also ensure a high compatibility between the ONFC and modified SAOED particles.…”

Preparation and Characterization of Polyvinyl Alcohol-Chitosan Composite Films Reinforced with Cellulose Nanofiber

“…The amount of absorbed water moisture in PVA/CS-1.0 film is the lowest as compared to other PVA/CS = 50/50 films with different TOCN content. Thus, it was suggested that the 1.0 wt % of TOCNs were well dispersed within the PVA/CS polymer matrix due to physical and molecular changes, which indicates the production of a more stable film [38,40]. From Table 3, it was indicated that T onset of the pure blended film was 272 °C.…”