Lignins thermal degradation

Fahmi R, Bridgwater A, Thain SC, Donnison IS, Morris PM, Yates N (2007) Prediction of Klason lignin and lignin thermal degradation products by Py-GC/MS in a collection of LoUum and Festuca grasses. J Anal Appl Pyrol 80 16-23... 

The complex three-dimensional structure of these materials is determined by their carbon-based polymers (such as cellulose and lignin), and it is this backbone that gives the final carbon structure after thermal degradation. These materials, therefore, produce a very porous high-surface-area carbon solid. In addition, the carbon has to be activated so that it will interact with and physisorb (i.e., adsorb physically, without forming a chemical bond) a wide range of compounds. This activation process involves controlled oxidation of the surface to produce polar sites. 

The thermal degradation of lignin occurs over a wide temperature range, from about 420-773 K. Several practical ways exist for the preparation of sulfur lignin. These are summarized in Table I. 

In the present study, PU s containing lignin were investigated with reference to thermal stability, which is one of the basic thermal properties of polymers. Thermal degradation of PU s which were obtained from solvolysis lignin was studied using thermogravimetry (TG). The inflammability of... 

Table I. Calculated Activation Energies (E s) for Thermal Degradation of Polyurethanes (PU s) and Lignin...

From the results obtained in this study, it is concluded that lignin in PU s retards the thermal degradation of PU s in air and also that PU s containing lignin become nonflammable in air with the addition of a polyol containing phosphorous. 

The list of pyrolysis products of cottonwood shown in Table VII (llj reflects the summation of the pyrolysis products of its three major components. The higher yields of acetone, propenal, methanol, acetic acid, CO, water and char from cottonwood, as compared to those obtained from cellulose and xylan, are likely attributed to lignin pyrolysis. Other results are similar to those obtained from the pyrolysis of cell-wall polysaccharides. This further verifies that there is no significant interaction among the three major components during the thermal degradation of wood. 

Faix O, Jakab E, Till F, Szekely T (1988b) Study on low mass thermal degradation products of milled wood lignins by thermogravimetry-mass-spectrometry Wood Set Technol 22 323-334... 

Faix O, Meier D, Fortmann I (1990a) Thermal degradation products of wood Gas chromatographic separation and mass spectrometnc characterization of monomeric lignin derived products Holz Roh- Werkst 48 281-285... 

Early interest in the thermal degradation of cellulose was stimulated by lively academic discussions about the origin of bituminous coal — whether it is derived from the lignin or carbohydrate constituents of wood. This subject was also investigated in an attempt to determine the significance of cellulose in commercial destructive distillation of wood and its contribution to the mixture of degradation products. 

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