Valorization of lignin in polymer and composite systems for advanced engineering applications – A review

Spherical lignin particles: a review on their sustainability and applications

“…With the societal demand for eco-friendly and renewable materials there has been an increasing interest to use lignin in various composite materials. As summarized in a recent review on lignin valorization, 148 lignin can enhance the mechanical and thermal stability of polymer blends or composite, act as adsorbing agent, or as reactive component in various resins, act as UV blocker, antimicrobial agent or flame retardant. 148 However, it has been observed that the use of raw, irregular lignin powders hinders high loads in composites, mostly because of the natural poor compatibility but also due to the uneven distribution of particles with varying size and morphology.…”

“…As summarized in a recent review on lignin valorization, 148 lignin can enhance the mechanical and thermal stability of polymer blends or composite, act as adsorbing agent, or as reactive component in various resins, act as UV blocker, antimicrobial agent or flame retardant. 148 However, it has been observed that the use of raw, irregular lignin powders hinders high loads in composites, mostly because of the natural poor compatibility but also due to the uneven distribution of particles with varying size and morphology. Spherical lignin particles with controlled surface chemistry could overcome these issues, thus allowing their broader use in composite applications and being very promising although the reported results are rather contradictory.…”

Comparing chemical composition and lignin structure of Miscanthus x giganteus and Miscanthus nagara harvested in autumn and spring and separated into stems and leaves

“…16 Lignins isolated from grass and wood-based LCF using different pre-treatments and/or depolymerization procedures are currently investigated for a broad variety of applications including lignin-based fuels, chemicals and polymer composites. 17,18 As a polyphenolic substance, lignin gained rising interest as substitute for fossil-based diols/polyols in polyurethane synthesis. [19][20][21][22][23] However, valorization of extracted lignin is still restricted to a few commercial products, mainly due to missing procedures for fast and reliable analysis of the highly complex 3D structure consisting of three randomly crosslinked monolignol units p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) (Fig.…”

Valorization of Technical Lignin for the Production of Desirable Resins with High Substitution Rate and Controllable Viscosity

“…Hence, the use of lignin as a cheap and renewable aromatic feedstock to produce value‐added chemicals or materials has considerable potential. Currently, lignin is considered as a source of phenols to replace phenol for the production of phenolic resins, which is one of the value‐added utilizations of technical lignin . In most lignin‐based phenolic resins, technical lignin must be modified to increase the number of reactive sites, such as hydroxymethylation, phenolation, ionic liquid modification, oxidative depolymerizaton, demethylation, and liquefaction .…”