Sustainable All-Cellulose Biocomposites from Renewable Biomass Resources Fabricated in a Water-Based Processing System by the Vacuum-Filtration-Assisted Impregnation Method

Abstract

The increasing awareness of global ecological concerns and the rising sustainability consciousness associated with the manufacturing of non-renewable and non-biodegradable composite materials have led to extensive research on product and process developments of more sustainable, environmentally friendly, and fully biodegradable biocomposites for higher-value end-use applications. All-cellulose composites (ACCs) are an emerging class of biocomposites, which are produced utilizing solely cellulose as a raw material that is derived from various renewable biomass resources, such as trees and plants, and are assessed as fully biodegradable. In this study, sustainable ACCs were fabricated for the first time based on the full dissolution of commercially available sulfite dissolving (D) pulps as a matrix with concentrations of 1.5 wt.% and 2.0 wt.% in an aqueous NaOH–urea solvent, and they were then impregnated on/into the pre-fabricated birch (B), abaca (A), and northern softwood (N) fiber sheets as reinforcements by the vacuum-filtration-assisted impregnation approach. This research aimed to investigate the effects of the impregnated cellulose matrix concentrations and types of the utilized cellulose fiber reinforcements (B, A, N) on the morphological, crystalline, structural, and physio-mechanical properties of the ACCs. The highest degrees of improvements were achieved for tensile strength (+532%, i.e., from 9.24 MPa to 58.04 MPa) and strain at break of the B fiber-reinforced ACC B1.5 (+446%, i.e., from 1.36% to 4.62%) fabricated with vacuum impregnation of the 1.5 wt.% cellulose matrix. Noticeably, the greatest improvements were attained in strain at break of the A and N fiber-reinforced ACCs A2.0 (+218%, i.e., from 4.44 % to 14.11%) and N2.0 (+466%, i.e., 2.59% to 14.65%), respectively, produced with vacuum impregnation of the 2.0 wt.% cellulose matrix. The study highlights the diverse properties of the all-cellulose biocomposite materials that could, expectedly, lead to further development and research for upscaled production of the ACCs.