Quantitatively evaluation of the effects of γ-irradiation dose and time on the structure and properties of lignin

ABSTRACTThe effects of γ-irradiation dose and process time on the structure and properties of alkali lignin have been quantitatively evaluated. According to the 13C CP/MAS NMR FTIR analyses, the γ-irradiation dose, D, and process time, t, on lignin structure have been known to break the side-chains of lignin, e.g. the C-β structure within the β-O-4, to enhance the C=O and C=C structure. By taking the NMR peak intensity of C=O structure, IC=O, and IR peak intensity of C=C structure, IC=C, as two measures, we obtained quantitatively relationships between D or t and those two lignin structures, respectively. Thermogravimetric analyses indicated that the lignin has an original thermal stability and its degradation was started since the applied dose at 300 kGy or the time up to 24 h at 100 kGy condition. The γ-irradiated lignin presented enhanced liquid adsorption due to the adsorbed water amount, Qt, increased with the D increase to follow a non-linear relationship.