Incorporation of lignins

S. S. Kelley, Incorporation of lignin copolymers into polyurethane materials, Ph.D. thesis, Virginia Polytech. Inst. State Univ., 1987, Univ. Microfilms Int., DA8814587. 

Li.gru.n-VeAd.ved Potyi ocqanaXeA Efforts to increase the incorporation of lignin into polyurethane products have concentrated on transforming polymeric lignins into polyisocyanates useful for reacting with polyols. Two alternative reaction pathways have been explored with the three lignin-like model compounds shown in Figure 3. These models were vanillic acid or a derivative thereof (Model Type A) a derivative of tetralin di-carboxylic anhydride (Model Type B) and a derivative of a styrene-maleic anhydride copolymer (Model Type C). 

Lignin is a potential substitute for oil-based phenols in phenolic and epoxy resins and adhesives [208, 209]. Incorporation of lignin into polymer matrix (polyolefin) offers certain benefits including improved chemical and/or physical properties, UV stabilization, and enhanced biodegradation capacity [209-212]. 

The incorporation of lignins in poly(olefins) and rubbers has attracted much attention within the very important context of polymer stabilization against degradation mechanisms involving free radicals, viz. oxidation, photolysis... 

Trenck Tvd, H Sandermann (1981) Incorporation of benzo[a]pyrene quinones into lignin. FEES Lett 125 72-76. 

Ralph, J. Lapierre, C. Lu, F. Marita, J. M. Pilate, G. Van Doorsselaere, J. Boerjan, W. Jouanin, L. NMR evidence for benzodioxane structures resulting from incorporation of 5-hydroxyconiferyl alcohol into lignins of O-methyl-transferase-deficient poplars. j. Agric. Food Chem. 2001, 49, 86-91. 

Quideau, S. Incorporation of p-hydroxycinnamic acids into lignins via oxidative coupling. Ph.D. Thesis, University of Wisconsin—Madison, USA, University Microfilms International 9428350, 1994. 1994. 

Incorporation of phenols (lignin) Manganese and iron peroxidases (plants)... 

Phenylalanine Ammonia-Lyase. The building units of lignin are formed from carbohydrate via the shikimic acid pathway to give aromatic amino acids. Once the aromatic amino acids are formed, a key enzyme for the control of lignin precursor synthesis is phenylalanine ammonia-lyase (PAL) (1). This enzyme catalyzes the production of cinnamic acid from phenylalanine. It is very active in those tissues of the plant that become lignified and it is also a central enzyme for the production of other phenylpropanoid-derived compounds such as flavonoids and coumarins, which can occur in many parts of the plant and in many different organs (35). Radioactive phenylalanine and cinnamic acid are directly incorporated into lignin in vascular tissue (36). 

Figure 6. Incorporation of tritiated phenylalanine into the compound middle lamella lignin and the secondary wall lignin determined by counting the silver grains. Symbols are as follows 0, compound middle lamella 0> secondary wall.

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