Adding value to lignins isolated from sugarcane bagasse and Miscanthus

Attempt to depolymerize industrial organosolv lignin (from sugarcane bagasse) and lignins extracted from sugarcane bagasse and Miscanthus fibers (isolated by a soda/anthraquinone process) in presence of an anthraquinone acid catalyst (AQCOOH) was described. With the aim to substitute formaldehyde by glutaraldehyde, a dialdehyde that can be obtained from natural sources, lignins were reacted with glutaraldehyde and studied as phenolic-type resins for thermosets. The reactions were predominantly analyzed be SEC and 31P NMR spectrometry. The Organosolv lignin–glutaraldehyde resin was used to prepare a composite reinforced with sugarcane bagasse fibers. Control samples were also prepared; specifically, composites based on phenol-formaldehyde and organosolv lignin–formaldehyde matrices. The results of the impact and the flexural strength tests of these composites showed that the organosolv lignin and glutaraldehyde can successfully replace phenol and formaldehyde, respectively.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Target: add value to lignins (Lig) from sugarcane bagasse and Miscanthus fibers. ► Anthraquinone derivative as catalysts/glucose/NaOH → improved Lig fragmentation. ► Depolym. Lig + glutaraldehyde/NaOH: phenolic-type resins. ► Resin based on sugarcane lignin → composites reinforced with sugarcane bagasse. ► Composites from high content of renewable raw materials and good properties.