Fractionation of Industrial Softwood Kraft Lignin: Solvent Selection as a Tool for Tailored Material Properties

Abstract

A simple approach for the fractionation of industrial softwood kraft lignin is presented in this work aimed at predictively obtaining readily usable lignin fractions with tailored material properties in a straightforward manner. This method is based on the use of three distinct solvents of different chemical nature to isolate soluble and insoluble fractions from the parent lignin by a single-step extraction process. A thorough characterization of the soluble and insoluble lignin fractions highlighted a direct correlation between the chemical-physical characteristics of the extraction solvent and the final properties of the recovered materials. In particular, hydrogen bonding interactions between solvent and lignin were demonstrated to play a major role in the extraction process, controlling to a great extent the final materials properties. The results of this study give a clear demonstration of a straightforward approach to access easily lignin fractions with well-defined characteristics and provide strong evidence of the direct correlation between solvent characteristics and properties of the extracted materials as predictive tool for the development of high-performance lignin-based systems. (Figure Presented)

Lignin nanoparticles by ultrasonication and their incorporation in waterborne polymer nanocomposites

“…Figure (a) presents the UV–vis absorption spectra of IND and NL‐6 h samples. In both cases, a maximum is observed at 280 nm which is ascribable to the presence of noncondensed phenolic groups in guaiacyl units that are characteristic of softwood lignin . In addition, a shoulder centered at 340 nm is present in the absorption spectra of both IND and NL‐6 h, although with different relative intensities.…”

“…In the attempt to tackle some of these limitations, several chemical and chemical–physical strategies have been proposed in the last few years to enhance the exploitability of lignin as macromonomer for the production of polymeric materials. To this end, different fractionation approaches (pH‐induced precipitation, membrane‐assisted ultrafiltration, and solvent extraction) have been used to improve the miscibility of lignin in common solvents while better controlling its chemical, structural, and physical properties . In addition, highly specific chemical functionalization reactions have been applied to lignin to improve its reactivity, add functionalities to its structure, and allow easier incorporation as reactive material into bio‐based thermoplastic and thermosetting polymers, including polyurethanes, (PUs) polyesters, phenolics, and epoxies …”

Modification of Kraft Lignin with Dodecyl Glycidyl Ether

“…To investigate the changes in the thermal behavior of KL derivatives, the glass transition temperature, T g , of the samples was determined, and the results are presented in Table . As reported previously, the T g of lignin varies depending on the type of lignin and the process through which the lignin is produced. The T g of KL is usually in the range of 90 and 170 °C.…”

Low‐temperature, Low‐Energy, and High‐Efficiency Pretreatment Technology for Large Wood Chips with a Redox Couple Catalyst

“…The molecular weight of lignin after pretreatment depends on the source and isolation and purification procedures employed. [59] [54] 3301 12 007 3.64 --birch alkali lignin [54] 3086 12 274 3.98 --spruceo rganosolv lignin [54] 846 2226 2.6 --birch organosolv lignin [54] 937 2150 2.3 ---Eucalyptus pellita Kraft-AQ pulping lignin [55] 492 493 1.0 ---SW kraftl ignin [56] 1100 1680 1.5 --oil palm lignin [57] 1263 874 1.44 --- ChemSusChem 2018ChemSusChem , 11,1 121 -1131 www.chemsuschem.org [52,53] Gel-permeation chromatography (GPC) was performed on recovered HW and SW lignin after pretreatment ( Figure S7).…”