This document describes the thermal analysis of kraft lignin using thermogravimetric methods.

Thermogravimetry can be used to determine the initial decomposition temperature(s), rate(s) of decomposition, and the temperature at maximum decomposition of various materials, including lignins at atmospheric pressure. All these temperatures are solely based on the mass loss and are not necessarily the real decomposition temperatures, because not all decompositions can generate evaporation at atmospheric pressure. Thus, these values are only for comparison purposes.

This procedure is applicable to solid lignins (e.g., powdered form) isolated using different isolation techniques (e.g., acidification with hydrochloric acid, sulphuric acid, etc., and carbonation using gaseous carbon dioxide) from the spent liquor (black liquor) generated in the kraft pulping process. It does not apply to raw black liquor.

Thermogravimetric measurement may be performed under different types of atmosphere, e.g., an inert atmosphere or an oxidative atmosphere.