Temperature-induced structural and chemical changes in cork from Quercus cerris

The effects of temperature on anatomical and chemical characteristics of Quercus cerris cork were examined. Cork samples were subjected to isothermal air heating between 150 °C and 400 °C and analyzed for mass loss, cellular structure and chemical composition.The thermal decomposition of Q. cerris cork is similar to that of Q. suber cork. Cork is thermally stable below 200 °C and after that degradation depended on temperature and heating time with increasing mass loss, i.e. 3% at 200 °C 10 min and 46% at 350 °C 60 min. With temperature and starting at 200 °C, cells expanded, cell wall thickness was reduced and corrugations were lost.Extractives degraded at lower temperatures, although aliphatic extractives were found to be more stable. Suberin from Q. cerris was more heat resistant than Q. suber suberin, while lignin showed similar resistance.These results provide a basis for studies on the production of Q. cerris bark expanded cork agglomerates for insulation purposes.

► Quercus cerris cork thermal decomposition is similar to that of Quercus suber.
► Thermal decomposition of cork cells starts at approximately 200 °C and increases with temperature.
► Over 200 °C, cork cell wall thickness decreases, cell wall corrugations disappear and cells expand to a maximum at 350 °C.
► Extractives are most heat sensitive components, but aliphatic extractives are more heat resistant than phenolic extractives.
► Q. cerris suberin is more heat resistant than Q. suber suberin.