All-Wood Composite Material by Partial Fiber Surface Dissolution with an Ionic Liquid

Abstract

Synthetic structural materials of high mechanical performance are typically either of large weight (for example, steels, and alloys) or involve complex manufacturing processes and thus have high cost or cause adverse environmental impact (for example, polymer-based and biomimetic composites). In this perspective, low-cost, abundant and nature-based materials, such as wood, represent particular interest provided they fulfill the requirements for advanced engineering structures and applications, especially when manufactured totally additive-free. Here, we report on a novel all-wood material concept based on delignification, partial surface dissolution using ionic liquid (IL) followed by densification resulting in a high-performance material. A delignification process using sodium chlorite in acetate buffer solution was applied to controllably delignify the entire bulk wooden material while retaining the highly beneficial structural directionality of wood. In a subsequent step, obtained delignified porous wood template was infiltrated with an IL 1-ethyl-3methylimidazolium acetate, [EMIM]OAc and heat activated at 95 °C to partially dissolve the fiber surface. Afterward, treated wood was washed with water to remove IL and hot-pressed to gain a very compact cellulosic material with fused fibers while retaining unidirectional fiber orientation. The obtained cellulose materials were structurally, chemically, and mechanically characterized revealing superior tensile properties compared to native wood. Furthermore, suggested approach allows almost 8fold tensile strength improvement in the direction perpendicular to fiber orientation, which is otherwise very challenging to achieve.

Quantitively Characterizing the Chemical Composition of Tailored Bagasse Fiber and Its Effect on the Thermal and Mechanical Properties of Polylactic Acid-Based Composites

“…The recycling of discarded NFs such as wood flour (WF), rice chaff (RF), bagasse fiber (BF), and sisal fiber (SF) has caught more and more people’s attention with the upgrading of environment protection as a priority. Compared with inorganic fibers such as glass fiber and carbon fiber, NF has advantages in terms of light weight, low cost, high strength, high modulus, and biodegradation, and have been widely used to prepare green composites [23,24,25,26].…”

Preparation of cellulose-rich membranes from wood: effect of wood pretreatment process on membrane performance

“…Cellulose is considered an abundant renewable resource of great potential for bio-based materials and products. The attractive mechanical properties of this biopolymer enable production of a wide range of cellulose-based materials (Zhang et al 2017;Khakalo et al 2019). The presence of many hydroxyl groups, which gives cellulose its remarkably high hydrophilicity, and the extensive network of inter-and intramolecular hydrogen bonds, which provides relatively high chemical and thermal stability, make cellulose an attractive material for filtration membranes (Woodings 2001;Ś lusarczyk and Fryczkowska 2019).…”

“…conventional viscose and carbamate processes and solvent systems for cellulose such as DMF/N 2 O 4 or DMSO/N 2 O 4 , CF 3 COOH, HCOOH/H 2 SO 4 and Cl 2 CHCOOH) and non-derivatizing solvents, which do not alter the cellulose chemistry but break hydrogen bonds within the cellulose microfibrils during the dissolution process (e.g. cupro, NMMOÁH 2 O and lithium chloride/N,Ndimethylacetamide (LiCl/DMAc)) (Pinkert et al 2009;Khakalo et al 2019). Existing conventional cellulose dissolution and membrane fabrication (both derivatizing and non-derivatizing solvent-based processes) require expensive, hazardous chemicals and cause significant pollution, so there is a need for novel non-derivatizing solvents whose dissolution mechanism maintains the beneficial characteristics of cellulose as a membrane material (Zhang et al 2017;Khakalo et al 2019).…”

“…Preparation of polymeric membranes using ILs as an effective and nonaggressive solvent for cellulose is the subject of intensive study. To cite several examples, Zhu et al (2014) studied preparation of membranes from cellulose extracted from pineapple leaves with the ionic liquid [Bmim]Cl; Chen et al (2012) investigated manufacturing of wheat straw regenerated cellulose membranes using the same IL; and Anokhina et al (2017) [OAc] has also been implemented for partial surface dissolution as a step in preparation of all-wood composites from delignified birch (Khakalo et al 2019). However, a thorough literature search yielded that preparation of a membrane directly from wood, which is an abundant source of cellulose, has not been reported.…”

Processing natural wood into bulk conducting materials

“…Wood is a traditional biomaterial with cellular structure [1] and has been long time widely studied and used for building and furniture construction. Very recently, some reports showed that the common wood can be treated as a high-strength material [2] or developed as wood-based functional materials [3][4][5][6][7].…”