Abstract
Bio-based wood materials are preferable for composites because of their sustainability, but adequately dispersing wood fibers in polymers can be difficult and costly. Our approach was to pretreat the wood with a green solvent system, allowing the composite to be extruded in a single step, simplifying the process, and reducing the overall cost. This study investigates the fibrillation of untreated wood sawdust (W) and deep eutectic solvent-treated wood sawdust (DESW) using a one-step twin-screw extrusion (TSE) process. The results of the analysis of wood fractions and optical microscopy confirmed that the one-step extrusion process resulted in fibrillation of both treated and untreated wood material. The width of the original wood particles was reduced by more than 99% after a one-step TSE for both untreated and DES-treated wood. The size reduction of the DESW was slightly greater than that of the untreated wood, and fibrillation was further confirmed by rheological analysis. The fibrillated wood was then compounded with polypropylene (PP) to produce a wood fiber-polypropylene composite with 50 wt % wood content. The elastic modulus of both untreated and treated extruded composites was higher than that of neat PP. The tensile strength and strain at break for the DESW-PP composite slightly increased in comparison to the untreated W-PP composite. Furthermore, DES treatment of wood resulted in a darker color and increased hydrophobicity of the material.
Highlights
The interest in using bio-based materials such as wood and cellulose in composite materials has increased due to the renewability of natural sources and their availability in many forms.[1−4] the extraordinary properties of biocomposites, in addition to their low cost and sustainability, are the main reasons for their further growth in transportation and construction applications as well as consumer goods.[5]
According to the morphological and rheological results, the wood sawdust was fibrillated using only a one-step twin-screw extrusion (TSE), and the deep eutectic solvents (DESs) treatment improved the degree of fibrillation and resulted in less fiber breakage
The DES treatment of the wood sawdust resulted in a dark brown color and more reduced affinity to moisture and turned the composites to a similar level of hydrophobicity as the PP matrix
Summary
The interest in using bio-based materials such as wood and cellulose in composite materials has increased due to the renewability of natural sources and their availability in many forms.[1−4] the extraordinary properties of biocomposites, in addition to their low cost and sustainability, are the main reasons for their further growth in transportation and construction applications as well as consumer goods.[5]. The pioneering work of cellulose fibrillation was presented by Herrick et al in 1983, where microfibrillated cellulose was isolated from different types of lignocellulose pulps.[10] Defibrillation of wood-based materials is usually achieved by chemical treatment such as 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-oxidation or mechanical disintegration using ultrafine grinding and homogenization processes, or a combination of these methods.[11−17] These approaches typically use very low fiber concentrations, usually 2 wt % or less, and they require a high energy consumption.[18,19]. Recent interest has focused on finding possible fibrillation processes that use higher fiber contents and consume less energy than the current methods.[9,20−22] Hietala et al used cellulose pulp and TEMPO-oxidized cellulose pulp with the aim of fibrillating cellulose during the biocomposite compounding process.[9] The results showed that the use of thermoplastic starch reduced the shear forces and that fibrillation was not efficient. They showed efficient fibrillation until sizes were reduced to the nanoscale, but the process was repeated several times and the extruder was cooled to 0 °C, which led to high energy consumption
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
