Nanocomposite Films Based on Xylan-Rich Hemicelluloses and Cellulose Nanofibers with Enhanced Mechanical Properties

Abstract

Interest in xylan-rich hemicelluloses (XH) film is growing, and efforts have been made to prepare XH films with improved mechanical properties. This work described an effective approach to produce nanocomposite films with enhanced mechanical properties by incorporation of cellulose nanofibers (CNFs) into XH. Aqueous dispersions of XH (64-75 wt %), sorbitol (16-25 wt %), and CNF (0-20 wt %) were cast at a temperature of 23 °C and 50% relative humidity. 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 thermal analysis (TG) and X-ray diffraction (XRD). The surface of XH films with and without CNF was composed primarily of nanonodules, and CNFs were embedded in the XH matrix. Freeze-dried XH powder was amorphous, whereas the films with and without CNF showed a distinct peak at around 2θ = 18°, which suggested that XH molecules aggregated or reordered in the casting solution or during water evaporation. Furthermore, the nanocomposite films had improved thermal stability. XH film with 25 wt % plasticizer (sorbitol, based on dry XH weight) showed poor mechanical properties, whereas incorporation of CNF (5-20 wt %, based on the total dry mixture) into the film resulted in enhanced mechanical properties due to the high aspect ratio and mechanical strength of CNF and strong interactions between CNF and XH matrix. This effective method makes it possible to produce hemicellulose-based biomaterials of high quality.

Nanocellulose in Thin Films, Coatings, and Plies for Packaging Applications: A Review

“…Several studies have shown that plasticizers can be used at controlled levels to adjust the degree of compliance or rigidity of films that contain nanocellulose reinforcements (Angles and Dufresne 2000;Dufresne et al 2000;López-Rubio et al 2007;Svagan et al 2007;Azeredo et al 2010;Mikkonen et al 2011;Peng et al 2011;Hansen et al 2012;Trovatti et al 2012ab;Barud et al 2013;Fortunati et al 2014;Pereda et al 2014;Alves et al 2015).…”

Holistic Rice Straw Nanocellulose and Hemicelluloses/Lignin Composite Films

“…HL powder was amorphous, showing a broad scattering centered at 2θ = 20°. 7/3 HL/S film exhibited a peak at 2θ = 18°and a small shoulder at 2θ = 21°( Figure 5), indicative of its partially crystalline structure, likely from the crystallinzation of xylan-rich hemicelluloses of rice straw as neither amorphous lignin nor sorbitol less than 50% 35,48 could impose crystalline structural change. Depending on the extraction methods and sources, rice straw hemicelluloses have shown to consist of 32−60% xylan, 8−43% glucan and a small amount of arabinan and galactan.…”

Chemical Pretreatments of Wood Chips Prior to Alkaline Pulping - A Review of Pretreatment Alternatives, Chemical Aspects of the Resulting Liquors, and Pulping Outcomes

“…In this approach, hemicelluloses represent many promising properties for the manufacture of value-added polymeric composites and blends, which could replace materials currently manufactured from fossil resources or even metals, such as aluminum (Alekhina et al 2014). Natural biopolymers are considered to have many advantageous properties when compared to their synthetic counterparts, as they are abundant, low-cost, biocompatible, nontoxic, biodegradable, and environmentally safe (Peng et al 2011b;Šimkovic et al 2011). Of the several possible hemicelluloses-derived polymeric applications, the manufacture of various polymeric films and hydrogels has garnered the most interest.…”