Lignin macromolecular properties

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). 

McNaughton JG, Yean WO, Goring DAI (1967) Macromolecular properties of kraft lignins from spruce made soluble by a continuous flow process Tappi 50 548-553 Michell AJ, Watson AJ, Higgins HG (1965) An infrared spectroscopic study of deligmfication of Eucalyptus regnans Tappi 48 520-532... 

Experimental data on hydrodynamic properties of natural and biosynthetic lignins in dilute solutions are reviewed. The results of viscometric, translational diffusion, and sedimentation studies provide evidence for the macromolecnles of lignin having a complex topological structure. The benefits and limitations of the theoretical approaches used to describe the topology of lignin macromolecular chains are discussed. The relationship between hydrodynamic characteristic and fractal properties of lignin is considered. 

Sarkanen, K. V. Ludwig, C. H. Editors Lignins Occurrence and Formation, Structure, Chemical and Macromolecular Properties, and Utilization, 1971. 

The chemical and macromolecular properties of lignin as well as its supra... 

Many, but not all, macromolecules are created by the mutual chemical chain reactions of small molecules called monomers and the arising species contain repeated small units, mers. In that case they are designated oligomers or polymers depending on their molar mass. This means that all oligomers and polymers can be called macromolecular substances but not all macromolecular substances are of oligomeric or polymeric nature (lignin, humin substances, etc.). Properties of macromolecular systems depend on... 

Most of the research on the macromolecular chemistry of lignin has been concentrated on iignosulfonates and kraft lignin because of the insolubility of lignin in its native state. The polymer properties are of importance for the evaluation of the technical applicability of lignin products. For theoretical considerations, see Sections 3.2.2 and 3.2.3. 

Russell WR, Forrester AR, Chesson A and Burkitt MJ (1996) Oxidative coupling during lignin pol)Tnerisation is determined by unpaired electron delocalization within parent phenylpropenoid radicals. Archives of Biochemistry and Biophysics, 332(2) 357-66 Russell WR, Forrester AR and Chesson A (2000) Predicting the macromolecular structure and properties of lignin and comparison with synthetically produced polymers. Holzforschung, 54(5) 505-10... 

In this chapter, polymer properties related to thermal stability and molecular motion of lignin in the solid state are discussed. Several papers on the molecular motion of in situ lignin have been published [39-42]. However, it is difficult to measure a single component in a biocomposite such as wood, since it contains three macromolecular species cellulose, hemicellulose, and lignin. In the past, the sensitivity of available experimental instruments was insufficient to detect the molecular... 

O.M. Sokolov, Macromolecular Reactions of Lignin at Alkali Cookings, Polymolecular Composition and Hydrodynamic Properties of Slightly Decomposed and Industrial Lignins, Institute of Wood Chemistry, Riga, Latvia, 1988. 

Three chapters are entirely devoted to lignin, covering (i) sources, structure and properties (Chapter 9), (ii) industrial processes and applications (Chapter 10) and (iii) their physical or chemical incorporation into novel macromolecular materials (Chapter 11). Moreover, its oxypropylation and the interest of the ensuing polyols are discussed in Chapter 12 and the properties of lignosulphonates as polyelectrolytes are dealt with in Chapter 24. 

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