Résumé
Wood heat treatment (WHT) is an eco-friendly preservation process to improve materialproperties, such as dimensional stability and durability. This value-added technique had a hugedevelopment in the last decades and, concerning heating rate and treatment duration, presentssimilar operating conditions to slow pyrolysis. The treatment is conducted within an inertatmosphere (nitrogen or vacuum) with a temperature ranging between 180 °C and 240 °C and ischaracterized by a low heating rate in the order of 0.25 to 1 °C min-1. Due to heat effect, woodpolymers undergo a thermodegradation characterized by a mass loss. This parametercharacterizes treatment progress and is used as a quality control indicator. The present studyaims to analyze the effect of treatment intensity (operating temperature for a given processduration) on thermodegradation of a hardwood species (Poplar, Populus nigra). Experiments wereperformed within a conduction oven under nitrogen on large scale boards (25 x 11 x 2.5 cm). Fivetemperatures were studied in a stablished range between 200-240 °C with a slow heating rate of1 °C min-1 and 10 h of treatment duration. A maximum mass loss of 21.02 wt% was observed atthe higher temperature (240 °C). The lower mass loss value 6.19 wt% was recorded for theexperiment performed at 200 °C. Based on measured data, a numerical model for instantaneousmass loss prediction during thermal process has been developed. A two-step kinetic mechanismwas adopted to simulate reaction rate of wood components degradation. The reaction rates fromnumerical results agree with observations reported in literature showing a more pronouncedthermodegradation when treatment temperature increases. A comparison between experimentaland numerical results allows the model’s accuracy evaluation.