Lignin composition

Thioacidolysis allows the distinction between products derived from lignin and products derived from />coumaric and ferulic acids, and the distinction between products derived from cinnamaldehydes and cinnamyl alcohols. Recent improvements have made it possible to estimate the fraction of free phenolic groups in uncondensed lignin (see Section 1.3.1), and to depolymerize the dimers, so that they can be included in the analysis of the lignin composition. 

Ash content was determined as follows At least 1 g of dry stems, ground to 60 mesh, was ashed in a muffle furnace at 650°C for 18-24 h. Ash content was calculated by weight difference. Carbohydrate and lignin compositions of untreated and treated straw samples were determined by quantitative saccharification using the method of Saeman et al. 

In the selection of starting material, one should be aware that there may be a variation in lignin composition depending on the part of a tree from which the wood is taken. Therefore, sapwood free of reaction wood should be used for the preparation of a reference lignin from a particular species. Size reduction and removal of extractives from the wood can be accomplished according to the directions given by Bjorkman (1956). 

Obst JR (1982) Guaiacyl and synngyl lignin composition in hardwood cell components Holzforschung 36 143-152... 

Sewalt, V.J.H., Ni, W., Blount, J.W., Jung, H.G., Masoud, S.A., Howies, P.A., Lamb, C. and Dixon, R.A. (1997) Reduced lignin content and altered lignin composition in transgenic tobacco down-regulated in expression of L-phenylalanine ammonia-lyase or cinnamate 4-hydroxylase. Plant Physiol., 115,41-50. 

Grabber, J. H., Mertens, D. R., Kim, H., Funk, C., Lu, F, and Ralph, J. (2008) Cell wall fermentation kinetics are impacted more by lignin content and ferulate cross-linking than by lignin composition. J. Sci. Food Agr. 89(1), 122-129. 

ATANASSOVA, R., FA VET, N., MARTZ, F., CHABBERT, B., TOLLIER, M.T., MONTIES, B., FRITIG, B., LEGRAND, M., Altered Lignin Composition in Transgenic Tobacco Expressing O-Methyltransferase Sequences in Sense and Antisense Orientation, Plant J., 1995,8,465-477. 

S. K. Samal, E.G. Fernandes, A. Crati, E. Chiellini. Bio-based Polyethylene-Lignin Composites Containing a Pro-oxidant/Pro-degiadant Additive Preparation and Characterization , J. Polym. Environ., 22, 58-68 (2014)... 

Some general guidelines for optimized lignin composite processing (ARBOFORM F-grades) on injection moulding machines are summarized below ... 

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