Ozonized lignin-epoxy resins

Ozonization of lignin forms derivatives of muconic acid that have the unique chemical structure of conjugated double bonds with two carboxyl groups. These derivatives have great potential for chemical modification. The ozonized lignin of white birch was soluble in epoxy resin at 120°C, and the free carboxyl groups were found to react with epoxide. This paper discusses developmental work on the preparation of pre-reacted ozonized lignin/epoxy resins the dynamic mechanical properties of cured resins and preliminary results of the application of these resins as wood adhesives. 

Preparation of Ozonized Lignin/Epoxy Resins. Each ozonized lignin (1.0 g) was mixed with DGEBA and heated at 120°C with stirring as described in the previous section. After heating for 30 min, the mixture was cooled to room temperature. The solidified reactants were dissolved in acetone (2 ml) and the curing reagents, diethylenetriamine (DETA) or hexamethylenedi-amine (HMDA), were added at 90% of the stoichiometric amount to epoxy equivalent. 

Figure 5. Temperature dependence of viscoelastic property of ozonized lignin/epoxy resins cured with hexamethylenediamine. Ozonized lignin content in DGEBA (1) 0 PHR (2) 20 PHR (3) 40 PHR (4) 80 PHR.

Table III. Tensile Shear Adhesive Strength of Ozonized Lignin/Epoxy Resins. (Normal Test)...

Tomita B, Kurozumi K, Takemura A, Hosoya S (1989) Ozonized lignin-epoxy resins, synthesis and use In Glasser WG, Sarkanen S (eds) Lignin, properties and materials American Chemical Society, Washington, DC, 496-505... 

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