Assessment of biomass alterations during hydrothermal pretreatment by in-situ dynamic mechanical analysis

This work proposes an original innovative in-house device able to characterize the evolution of viscoelastic properties of lignocellulosic products during hydrothermal pretreatment (water-saturated conditions up to 190 °C). The main objective is to assess the cooking phase before steam explosion. We designed and built a novel experimental device for analyzing the dynamic mechanical analysis of the biomass soaked in water or acidic water. The device allows the sample to be loaded/unloaded during the test with an accurate measurement of deformation and force despite the severe conditions. This system can perform the mechanical test on immersed samples under controlled pressure (up to 1.5 MPa) and temperature (up to 190 °C). Experiments were performed with poplar via harmonic and periodic tests. The experimental data collected on poplar allows the characteristic time constants of the thermo-chemical reactions to be obtained as a function of the operating conditions. [Display omitted] •Innovative device for in situ measurement of rheological properties during cooking.•The generation of datasets for isothermal cooking of poplar in the range 140 °C–190 °C.•Clearly distinguished thermal activation and degradation kinetics of poplar.•The derivation of a mathematical model for predicting degradation kinetics.