Sustainable Barrier System via Self-Assembly of Colloidal Montmorillonite and Cross-linking Resins on Nanocellulose Interfaces

Abstract

Cellulose nanofibrils (CNFs) are able to form strong oxygen-barrier films suitable for food packaging but lack the needed water resistance in comparison to plastics. Desired water barrier quality can be achieved by applying mineral additives within the nanofibrils network. In current contribution, a sustainable hybrid system with an improved water barrier function is proposed by incorporating colloidal montmorillonite nanoclay (MMT) and two cross-linking agents, namely, polyamidoamine epichlorohydrin (PAE) and Acrodur thermoset acrylic resin (ACR) into CNF interfaces. Continuous matrices were produced via evaporation-induced self-assembly of colloidal building blocks followed by appropriate heat-curing regime to impart internal cross-linking. The development of chromophore functionalities and formation of ester motifs on the hybrid matrix (with no evidence of degradation) were detected by Fourier-transform infrared (FT-IR) spectroscopy. Intercalation of clay, solely, reduced the water vapor transmission rate (WVTR) to some extent; however, a more remarkable decline (by 60%) was observed upon the curing and cross-linking process. In fact, combination of clay platelets and cross-linkers contributed to a denser film structure and restricted water passage. Also, an excellent resistance to oil and grease was observed in all the studied films (Kit number of 11). A reduction in tensile strengths and resistance to cracking at fold was noted and ascribed to MMT interference in cellulose interchain hydrogen bonds. This however was counteracted by the introduction of cross-linkers, apparently by aiding stress transfer within the matrix. MMT imparted a limited elevation in the surface free energy, pointing out to an induced hydrophilicity; however, surface energy values declined markedly upon using cross-linkers. Finally, thermal stability of hybrids was adversely affected, compared to neat CNFs. Our study suggests the potential utilization of low-cost, sustainable biobarrier films for application in food/drug packaging, where low permeation of moisture is highly desirable.

Greaseproof paper products: A review emphasizing ecofriendly approaches

“…The most accepted way to evaluate greaseproof papers that have been treated in some way with perfluorinated compounds is called the kit test, which is specified in TAPPI Method T559 cm-02 (TAPPI 2002). This test uses a series of 12 solutions with different ratios of caster oil to toluene to n-heptane.…”

“…In view of the earlier discussion of tortuosity, it should not be surprising that promising results for resistance to grease and various gases have been achieved in systems in which highly platy minerals were used as an ingredient in film in barrier layers that were mainly comprised of MNFC or CNC (Sanchez-Garcia et al 2010;Liu et al 2011;Aulin et al 2012;Wu et al 2012;Rhim et al 2013;Rastogi and Samyn 2015;Tyagi et al 2018). Though most such studies did not report results for grease resistance, those that did so achieved promising results (Tyagi et al 2018(Tyagi et al , 2019Tayeb and Tajvidi 2019).…”

Nanoclays in food products: benefits and possible risks (literature review)

“…НГ ввиду свой высокой удельной площади поверхности и ионообменных свойств обладают значительной адсорбционной емкостью, из-за чего между их слоями возможно встраивание (интеркаляция) органических молекул, а органомодифицированные НГ легко внедряются в объем гидрофобных органических полимеров с образованием планарных структур (нанокомпозитов) [13]. Одним из наиболее важных свойств глинистых нанокомпозитов является непроницаемость пластин НГ для молекул газов (кислорода, двуокиси углерода), а также воды, в силу чего значительно удлиняется проходимый данными молекулами путь в процессе диффузии через полимер [14] (рис. 4).…”

Cross‐Linked Nanocellulosic Materials and Their Applications

“…The wet polyamide epichlorohydrin resin/TEMPO‐oxidized CNFs (PAE–TOCNFs) films with 0.9 wt % PAE had 95 MPa in tensile strength, 6.3 GPa in Young's modulus, and 2.4 % strain at breakage with 2.6‐, 0.7‐, and 0.8‐fold improvements, respectively, compared to PAE–TOCNFs films with 0.1 wt % PAE . The enhanced mechanical properties of cross‐linked NC‐based materials showed the potential to be used in medical, food, and drug packaging . In addition, the better wet mechanical performance improves the applications of NC‐based materials under high‐humidity conditions …”