Thermogravimetric analysis of cork and cork components from Quercus variabilis

Cork and cork components (suberin, lignin, holocellulose, sclereids, and lenticels) were obtained by manual and chemical methods. Dynamic thermogravimetric analysis was used to investigate the thermal behavior of cork and its components. Thermal decomposition of cork was different from that of natural fibers. Characteristic temperatures of thermal decomposition for cork and impurities (sclereids and lenticels) were related to their chemical components. Cork lignin has the decomposition characteristics of G-type (guaiacyl units) lignin, typical of softwood with high residual solids. The pyrolysis characteristics of Quercus variabilis Blume (Q. variabilis) suberin was close to Quercus cerris L. (Q. cerris) suberin. The decomposition temperature range of cork, lignin, or suberin was wider than that of sclereids, lenticels, or holocellulose. Activation energy of cork was lower than that of natural fibers. The activation energy of cork and the extracted suberin was slightly increased when the conversion rate α was greater than 0.35. Activation energies of sclereids and lenticels were close to each other due to similar composition and proportion in them.