Abstract
Through the phase separation treatment with a concentrated acid and a phenol derivative, 80 % of native lignins in rice straw got ether soluble, having high frequency of combined phenols. The successive phase separation treatments of rice straw, followed by western hemlock were carried out. In this process ether soluble fractions from native lignin in rice straw worked as external nucleophiles to native lignin in western hemlock. With increasing the mol ratio of western hemlock- to rice straw lignins, a yield, a weight-average molecular weight (Mw) and a content of methoxyl group of resulting lignin derivatives (acetone soluble, ether insoluble fractions) got higher, having lower and broad absorption at 815 cm-1 in FT-IR spectra, attributed to C-H out of planes skeletal vibration of aromatic ring despite the same contents of combined p-cresol. These results suggested the formation of hybrid types of lignins composed of rice straw- and western hemlock lignins.
