Properties of lignin

The molecular weight of lignin in the wood, ie, of protolignin, is unknown. In addition to difficulties of isolation and purification, the polymer exhibits strong solvent, ionic, and associative effects in solution. An unequivocal method of measurement has not been developed. The polymer properties of lignin and its derivatives have been discussed (10,16). 

The discrepancies encountered on attempting to interprete the physico-chemical properties of lignin are even more striking. For example, there are reported in the literature values for the molecular weight of lignin1 ranging from 250 to the colloidal dimensions of 12,000 (16). 

Solution prepregging, 20 284-285 Solution processing, 14 80 Solution process, of ethylene-propylene polymer manufacture, 10 708-710 Solution properties of lignin, 15 13 of polyampholytes, 20 479 ofVDC copolymers, 25 703-706 Solution spectrophotometry, 9 232 Solution spinning... 

These complications proved to be the greatest deterrents to identification of the structure of lignin. Without knowledge of the make-up of lignin, it is clear that little promise could be expected from empirical studies directed at finding useful applications for it. In view of this situation, there has been a great intensification in fundamental research on the structure and properties of lignin in the hope that a better scientific foundation could be laid for future applied research. 

PUot-Scale Production and Properties of Lignin Peroxidases... 

It is well known that the structure, distribution and properties of protolignin in cell walls vary according to cell type and morphological location. This is based upon extensive studies on topochemical properties of lignin using various methods such as ultraviolet microscopic photometry (1,2), bromination-SEM-EDXA (3) and other physical or chemical analyses of isolated tissue fractions (4). 

Because of the polyelectrolyte properties of lignins, elution is performed with electrolyte solutions. If the lignins are water soluble and the column... 

The understanding of the macromolecular properties of lignins requires information on number- and weight-average molecular weights (Mn, Mw) and their distributions (MWD). These physico-chemical parameters are very useful in the study of the hydrodynamic behavior of macromolecules in solution, as well as of their conformation and size (1). They also help in the determination of some important structural properties such as functionality, average number of multifunctional monomer units per molecule (2, 3), branching coefficients and crosslink density (4,5). 

Effect of Soft-Segment Content on the Properties of Lignin-Based Polyurethanes... 

All of the chemical evidence that can be marshalled indicates that wood fiberboard manufacture exploits the thermoplastic properties of lignin. Defibering is effected by the thermal softening of lignin in the middle lamella at saturated steam pressures above 130C. Interfelted fiber mats are consolidated with or without densification pressure by the thermoplastic fusion of lignin-rich fiber surfaces at high board conversion temperatures. 

Ferapontova EE, Castello J, Gorton L (2006) Bioelectrocatalytic properties of lignin peroxidase from Phanerochaete chrysosporium in reactions with phenols, catechols and lignin-model compounds. Biochim Biophys Acta 1760 1343-1354... 

Physico-chemical properties of Lignin peroxidase isoenzymes from Phanerochaete... 

Farrell RL, Murtagh KE, Tien M et al (1989) Physical and enzymatic properties of lignin peroxidase isoenzymes from Phanerochaete chrysosporium. Enzyme Microb Technol 11 322-328... 

Shevchenko, S. M., Chang, K., Dick, D. G., Gregg, D. J., and Saddler, J. N., Structure and properties of lignin in softwoods after S02-catalyzed steam explosion and enzymatic hydrolysis. Cellulose Chem Technol 2001, 35 (5-6), 487-502. 

Spectroscopic Properties of Lignin Peroxidase and Manganese Peroxidase... 

Bjorkman A, Person B (1957) Studies on finely divided wood Part 2 The properties of lignins extracted with neutral solvents from softwoods and hardwoods Sven Papperstidn 60 158-169... 

Kawamura I, Higuchi T (1964b) Studies on the properties of lignins of plants in various taxonomical positions II On the I R absorption spectra of lignins Mokuzai Gakkaishi 10 200-206... 

Kawamura I, Shinoda Y, Ai TV, Tanada T (1977) Chemical properties of lignin of Eyrthrma wood Mokuzai Gakkaishi 23 400-404... 

Thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC) are the most frequently used techniques in lignin chemistry, although thermomechanical analysis (TMA) has also been used effectively in the analysis of thermal properties of lignin (Goring 1963). In this section, the principles of TG, DTA, and DSC, and their application to lignin are described. 

Lignin is a complex amorphous polymer composed of a cross-linked and branched network phenylpropane units. Thermal analyses such as TG, DTA, and DSC are useful for elucidating the physicochemical properties of lignin. 

Most of the data accumulated to date reflect structural information at the molecular level Very little effort has been invested in studies of the polymer properties of lignin by nC NMR techniques... 

Pepper JM, Baylis PET, Adler E (1959) The isolation and properties of lignins obtained by the acidolysis of spruce and aspen woods m dioxane-water medium Can J Chem 37 1241-1248... 

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