Chemical changes to woody polymers due to high-temperature thermal treatment assessed with near infrared spectroscopy

Near infrared spectroscopy and an original approach for visualisation of spectra are proposed here for characterisation of vacuum thermally modified samples of eight wood species representing softwoods and hardwoods. Significant changes in absorption bands were observed in conjunction with an increase of treatment temperature. A novel method for visualisation of the degradation patterns (xylograms) is capable of highlighting peculiarities in chemical changes to woody polymers due to the thermal treatment. This method also allows observation of kinetics and permits comparison of thermal stability of investigated species. Such knowledge might be help- ful for further optimisation of thermal treatment procedures at an industrial scale. Furthermore, xylograms as a simple and illustrative method might be suitable for visualisation of other modification processes of wood as well as of other materials.