Butanol-Based Organosolv Lignin and Reactive Modification of Poly(ethylene-glycidyl methacrylate)

Abstract

Biomass processing industries and modern society are both interested in environmentally friendly plantbased polymers, such as lignin, to replace petrochemical derivatives. In this study, an n-butanol-based solvent system that can be produced through fermentation of cellulosic biomass, was used to fractionate hybrid poplar and isolate high purity lignin. The resulting unique glassy lignin fraction exhibited good melt-flow characteristics but poor mechanical behavior. Therefore, to produce a reusable and tough thermoplastic material, the lignin was reactively blended with glycidyl methacrylate modified polyethylene plastic using a high shear melt-mixing technique at 170 °C. Mechanical and rheological analyses revealed that the reactively processed blends with 30 wt % lignin have good compatibility between both polymers. Scanning electron microscopy, dynamic mechanical thermal analysis, and infrared spectroscopy data indicated improved interaction between lignin and the functional polyethylene matrix. The blends exhibited a thermal relaxation in the temperature range of 10 to 20 °C, because of the branched glycidyl methacrylate moiety. The optimal composition, consisting of 30% lignin, exhibited ∼10 MPa tensile strength with 50% strain to failure; such a lignin-modified polymer may find use as packaging, as textile coatings, and in various horticultural applications.

Organosolv Lignin Improved Thermoplastic Elastomeric Behavior of Polyethylene/Polyisoprene Blend

“…Interestingly, lignin addition decreased the equilibrium mixing torque, which is attributed to the presence of the non-crosslinked lignin phase in the blends. As reported elsewhere, 28 this organosolv lignin had a low meltviscosity at elevated temperatures compared to LDPE resin; therefore, in the blends, non-crosslinked low-viscous lignin acts as a plasticizing agent and facilitates the mixing procedure by reducing the overall melt viscosity of the blends. The reduced mixing torque reflects less energy requirement when considering large-scale product manufacturing.…”

“…The lower tensile strength and strain of the materials containing a high amount of lignin (10% and more) are attributed to the presence of a more non-crosslinked lignin phase. Lignin is a low-molecular-weight (2262 Da) additive and mechanically fragile or brittle at ambient conditions when compared with the LDPE resin (135–163 kDa).…”

“…It had a purity of 93.4 wt. % with an average molecular mass of 2262 Da, and aliphatic OH groups of 4.4 mmol/g, phenolic OH groups of 3.1 mmol/g, and syringyl OH groups of 2.1 mmol/g …”

“…Thus, lignin has the potential to significantly improve the TPE behavior of a polymeric material . Among the different extraction techniques, the organosolv process produces lignin chemicals with less sulfur crosslinked and salt-free structures with high purity. − Particularly, lignin extracted from softwood such as hybrid poplar tree via organosolv fractionation consists of high syringyl/guaiacyl monolignol ratios, which can lead to good melt-stability and flow behavior in the temperature range of 140 to 170 °C, , similar to that of traditional polyethylene resins such as low-density polyethylene. Therefore, it is anticipated that this organosolv lignin can produce homogeneous blends with low-density polyethylene (LDPE) via the melt-compounding technique when appropriate compatibilizing or crosslinking additives are used.…”

Electrocatalytic Lignin Oxidation

“…Metal oxide electrodes have been widely studied for lignin oxidation reactions because of their innate high electrocatalytic activities for organic oxidations. ,− Specifically, metal oxide interfaces offer the possibility of inner-sphere electron-transfer pathways that can facilitate lignin oxidation relative to graphitic carbon electrodes. The earliest published effort in this direction dates to just after the second World War when Brooks and co-workers demonstrated the electrochemical oxidation of butanol-based organosolv lignin in a 1% NaOH solution using an oxidized lead (Pb) electrode …”