Fractionation of Kraft Lignin for Production of Alkyd Resins for Biobased Coatings with Oxidized Lignin Dispersants as a Co-Product.

A new valorization pathway based on solvent fractionation was applied to kraft lignin, a major by-stream of the pulping industry, to extract a soluble lignin intermediate featuring an improved structural homogeneity, a low molecular weight, and a high content of phenolic hydroxyl and carboxylic acid groups to serve as a substitute of the nonrenewable polyacids in the formulation of alkyd resins, a dominant material used in the production of anticorrosion surface coatings. Herein, softwood kraft lignin was mixed in a low-cost green solvent, aqueous ethanol, prepared at different ratios, at room temperature to generate a soluble fraction of a low of ≤2200 g mol and an insoluble fraction of a high of ≥3950 g mol of lignin. The best combination of yields and molecular weights of soluble lignin (16-36% yield, 1740-1890 g mol) was attained using 50-80 vol % ethanol in fractionation.

Sustainable Materials: Production Methods and End-of-life Strategies.

All three natural polymers of biomass and the monomer platforms derived from them present multiple avenues to develop products from specialty to bulk markets, which could serve as entry points into the industry for bio based sustainable materials. However, several roadblocks still exist in the pathway of technology development of these materials due to challenges related to cost-competitiveness, scalability, performance and sustainability. This review outlines these major technical challenges as four key checkpoints (cost-competitive, scalability, sustainability, performance) to be addressed for successful market entry of a new sustainable material.