Comparison of Major Wood Hygro-Thermal Modification Technologies Paves the Way for a Generalized Mass Loss Kinetic Model

Abstract

Bibliographic data about dry mass loss coming from different thermal and hygrothermal modification processes versus time were collected in this work and analyzed together. The data sets were collected from 2 experimental campaigns involving different modification technologies: (A) spruce wood hygro-thermally modified under superheated steam conditions performed at relative humidity ranging from 35 to 92% at temperatures ranging from 110 to 170 °C; and (B) poplar wood samples thermally modified with Thermo-vacuum® technology performed at temperatures ranging from 150 to 240 °C. For both processes, conversation rates master curves at 150 °C were identified on the experimental points using the time-temperature and the time-temperature-humidity superposition method. The two master curves were then compared and a generalized kinetic model able to predict the mass losses when modifying wood at different temperatures and relative humidity implemented. A kinetic model is expressed with a master curve composed of 2 kinetic stages. That model can predict the mass variation occurring during any hygrothermal modification whatever the temperature applied and the environment medium relative humidity.