Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectroscopy showed that methylolated kraft lignin has more hydroxymethyl groups than glyoxalated kraft lignin. For the epoxidization reaction we studied the influence of the lignin:NaOH (w/w) ratio, temperature, and time of the reaction on the properties of the prepared epoxidized lignins. The structures of lignin-based epoxy resins were followed by epoxy index test and FTIR spectroscopy. Optimal conditions were obtained for lignin-based epoxy resin produced at lignin/NaOH = 1/3 at 70 ºC for 3h. Thermogravimetry analysis (TGA) revealed that the epoxidization enhances the thermal stability of lignins and may allow a wider temperature range for applications with lignin epoxy-PF blends.

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A novel low-temperature curing polytriazole resin was prepared from a triazide and a tetraalkyne and characterized. The resin can be cured at 70-C. The glass transition temperature T g and thermal decomposition temperature T d5 of the cured resin with the molar ratio of azide to alkyne group [A]/ [B] ¼ 1.0:1.0 reached 324 and 355-C, respectively. The study on the curing kinetics of the resin shows that the apparent activation energy of the curing reaction is 93 kJ mol S1 . The flexural strength of the cured resin reached 137.6 MPa at room temperature and 102.6 MPa at 185-C.Low temperature curing polytriazole resin 557 1608C/2hr, 1808C/2hr, and 2008C/2hr, the DSC curve of the cured A 3 B 4 resin is shown in Fig. 4. As shown in Fig. 4, there was no thermal effect in the whole scanning. This indicates that the curing reaction of A 3 B 4 resin has been completed. Thermal properties of the cured A 3 B 4 resinDMA of the cured A 3 B 4 resin was performed under nitrogen atmosphere. The result is shown in Fig. 5. The glass transition temperature of the cured A 3 B 4 resin reaches 3248C. Thermo-gravimetric curves of the cured A 3 B 4 resin under Scheme 1. Schematic polymerization of A 3 and B 4 .