Abstract:

This paper reported a study on the change process of the macro?carbon formation of tea polyphenols. Thermogravimetry was conducted for tea polyphenols using a synchronous thermal analyzer in different atmospheres and at different heating rates. The Kissinger’s and Ozawa’s methods were employed to calculate the activation energy of tea polyphenols in different atmospheres. The results indicated that an expanded carbon layer was formed for tea polyphenols after heated， and it could retain a complete carbon skeleton at high temperatures. Tea polyphenols exhibited a good thermal stability. There is a rapid weight loss only when heating temperature exceeds 200 °C. The carbon residue rate of tea polyphenols reached 29.69 wt% in nitrogen at a heating temperature of 800 °C， and the carbon residue rate reached 9 wt% in air. The average activation energy of tea polyphenols in nitrogen was greater than that in air. However， the activation energy in air was greater than that in nitrogen in the initial heating stage.

Key words: tea polyphenol, charring performance, thermal property, thermal decomposition, activation energy