Composite of Cellulose-Nanofiber-Reinforced Cellulose Acetate Butyrate: Improvement of Mechanical Strength by Cross-Linking of Hydroxyl Groups

Abstract

A great challenge hindering the use of cellulose nanofibers (CNF) as a reinforcing filler in bio-based polymeric matrices are their poor chemical compatibility. This is because of the inherent hydrophilic nature of CNF and the hydrophobic nature of the polymeric matrix. In this study, cellulose laminates were prepared by using CNF as a filler and cellulose acetate butyrate (CAB) as the polymer matrix. To improve the compatibility between CAB and CNF, the residual hydroxyl groups of CAB and the hydroxyl groups on the surface of CNF were cross-linked with bio-derived polyisocyanurate D376N (STABiO™). The composite material was obtained in one step by sandwiching a CNF sheet (10 wt%) coated with a cross-linking agent between CAB films (90 wt%) using hot pressing. When 14.3 wt% of the cross-linking agent to the total weight of CNF and CAB was added, the tensile strength and flexural strength were improved by 72.4% and 16.3%, respectively, compared with neat CAB. It was concluded that this increase in strength is a result of both: cross-linking between the CNF sheets as well as the cross-linking occurring at the CNF/CAB interface.

Polymeric Wet-Strength Agents in the Paper Industry: An Overview of Mechanisms and Current Challenges

“…Different techniques can be used for investigating the performance of a specific wetstrength agent, including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), tensile strength testing (INSTRON), dynamic mechanical analysis (DMA), and wet-peel and thermogravimetric analysis (TGA) (Figure 11). [82]); (d) FTIR spectra of cottonseed protein (CSP) isolate and paper samples treated with CSP or CSF and nanocellulose (CNC), expansion of the cellulosic region of the amide bonds (1750 cm −1 to 1400 cm −1 ) (reproduced from [83]).…”

“…(A) A-CNF; (B) CAB500-5; (C) CAB/D376N (0 wt%); (D) A-CNF/D376N (3.9 wt%); (E) CAB/A-CNF/D376N (7.7 wt%); (F) CAB/A-CNF/D376N (14.3 wt%); (G) CAB/A-CNF/D376N (24.5 wt%). (Reproduced from[82]); (d) FTIR spectra of cottonseed protein (CSP) isolate and paper samples treated with CSP or CSF and nanocellulose (CNC), expansion of the cellulosic region of the amide bonds (1750 cm −1 to 1400 cm −1 ) (reproduced from[83]).…”