Sustainable Development of Hot-Pressed All-Lignocellulose Composites-Comparing Wood Fibers and Nanofibers.

Erfan Oliaei,Tom Lindström,Lars A Berglund

doi:10.3390/polym13162747

Abstract

Low-porosity materials based on hot-pressed wood fibers or nanocellulose fibrils (no polymer matrix) represent a new concept for eco-friendly materials with interesting mechanical properties. For the replacement of fossil-based materials, physical properties of wood fiber materials need to be improved. In addition, the carbon footprint and cumulative energy required to produce the material also needs to be reduced compared with fossil-based composites, e.g., glass fiber composites. Lignin-containing fibers and nanofibers are of high yield and special interest for development of more sustainable materials technologies. The present mini-review provides a short analysis of the potential. Different extraction routes of lignin-containing wood fibers are discussed, different processing methods, and the properties of resulting fiber materials. Comparisons are made with analogous lignin-containing nanofiber materials, where mechanical properties and eco-indicators are emphasized. Higher lignin content may promote eco-friendly attributes and improve interfiber or interfibril bonding in fiber materials, for improved mechanical performance.

Highlights

Fossil-based plastics are widely used in the form of molded components, for example in appliances, cars, general industry and transport, consumer goods, packaging, and furniture [1,2]
Abe and coworkers [10] investigated hot-pressed nanocellulose films based on microfibrillated cellulose from chemo-thermomechanical wood pulp. They found that hot-pressed films showed a shiny surface, indicating that the ligninhemicellulose mixture in the fibrils showed liquid-like flow during the molding operation. The objective of this mini-review is to analyze the potential of lignin-containing wood fibers and nanofibers in the context of binderless hot-pressed fiber materials akin to molded fibers, but with lower porosity
For the SE-Microfibrillated Lignocellulosic Nanofibers (MFLC) nanocellulose and hot-pressed wood fibers (HP-WF) wood fiber materials in Figure 6b of about 25% porosity, it is interesting that ultimate strength and modulus may improve with lignin content up to about 17% lignin

Summary

Introduction

Fossil-based plastics are widely used in the form of molded components, for example in appliances, cars, general industry and transport, consumer goods, packaging, and furniture [1,2]. The selfbonding of lignin-derived moieties, i.e., condensation repolymerization, cross-linking and coupling to other wood components, such as hemicelluloses or cellulose possibly occurs, serving to the binder function [9] This may improve the mechanical properties, though it may aggravate recyclability. Abe and coworkers [10] investigated hot-pressed nanocellulose films based on microfibrillated cellulose from chemo-thermomechanical wood pulp They found that hot-pressed films showed a shiny surface, indicating that the ligninhemicellulose mixture in the fibrils showed liquid-like flow during the molding operation. The objective of this mini-review is to analyze the potential of lignin-containing wood fibers and nanofibers in the context of binderless hot-pressed fiber materials akin to molded fibers, but with lower porosity. The recent interest in nanocellulose motivates a comparison of mechanical properties and candidate applications of hot-pressed films and materials based on wood fibers or lignocellulose nanofibers

Lignin-Containing Wood Pulp Fibers

Molded Wood Pulp Fibers

Aspects of Sustainable Development

Findings

Conclusions and Perspective