Lignin-containing polymers

Recent systematic studies on the relation between network structure and substituents in kraft lignin, steam exploded, have shown that the lignin containing networks can be modified in new ways, cf. e.g. (80). Also the toughening of glassy, structural thermosets can be achieved by incorporating a variety of polyether and rubber-type soft segment components in the polymer network structure. 

Initial work used Whatmans filter paper (cotton based) as a control and Figure 2 shows that as the X polymer deposited within the paper structure increases the fold endurance also Increases. Figure 3 shows a similar relationship for a lignin containing (wood based) paper, although the strength increases are usually less dramatic. 

In a previous paper (21) we characterized aromatic acids trapped in lignite coal, and have found that these acids are quite similar qualitatively to those obtained from the present oxidation of the same pretreated coal. This indicated that the trapped acids were derived mainly from the hydrolytic degradation of lignin-like polymers. We also have observed that no trapped organic acid is isolated from the anthracite coal that no longer contains lignin-like polymers. 

Nature is composed of minerals, air, water, and living matter. The latter contains polymers. The most abundant natural polymer is cellulose. It, together with lignin and hemicelluloses, are the principal components of plants. The principal function of lignin in plants is to assist in the movement of water the lignin forms a barrier for evaporation and, thus, helps to channel water to critical areas of the plant. 

Methods for the isolation of lignin polymers, and for use of the isolated lignin polymers have been described (39). Lignin containing compositions can be used in carbon fiber composites, resins, adhesive binders and coatings, PLf-based foams, rubbers and elastomers, plastics, films, paints, nutritional supplements, food and beverage additives. Lignin polymers may be produced at low cost, and may... 

The structure and chemical makeup of natural fibers varies greatly and depends on the source and many processing variables. However, some generalizations are possible. Natural fibers are complex, three-dimensional, polymer composites made up primarily of cellulose, hemicellulose, pectins, and lignin [12]. These hydroxyl-containing polymers are distributed throughout the fiber wall. The major chemical components of selected natural fibers are listed in Table 11.1. 

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