Lignocellulosics track

Study of biomass pretreatment processes 

The pretreatment processes of biomass allow to improve its later use via morphological, physicochemical and properties modifications. Thus, different pretreatments and their impacts on biomass are studied: grinding, acid cooking, steam explosion, torrefaction, pyrolysis, thanks to original experimental devices and the imaging platform. The understanding and the modeling of the modifications during the treatment make it possible to anticipate the impact of the processes and to optimize their control with optimal conditions according to the biomass. 
The modeling is based on a DAEM (Distributed Activation Energy Modeling) approach to predict the alteration of biomass properties from any operating conditions (temperature versus time). The modeling of coupled heat and mass transfers in porous media allows to study the effect of sudden changes of boundary conditions: for example, very fast heating phase at the beginning of acid cooking and steam explosion.

Design of composites with optimized properties 

The study of structure-property relationships is developed from 2D/3D morphological observations, dynamic in situ observations under stress, and various characterizations of properties (hydric, thermal, mechanical), allowing the development of predictive models of the properties of biobased composite materials from real morphology. Our remarkable equipment in high resolution imaging allows us to take into account the local morphological heterogeneity of biomasses and materials (fiber orientation, fiber-resin arrangement...), thus refining the predictive multi-scale modeling and anticipating accurately the behavior of materials. 
The team wishes to rely on the development of virtual morphologies and machine learning methods from the databases of materials already studied, to innovate in the design of materials with optimized properties by reverse engineering approaches. 
 

Characterization of coupled transfers 

To feed and validate all our predictive simulation tools, the team has developed a unique expertise in characterization at different scales. This allows us to offer a very complete range of characterization of solid materials, which can be divided into three categories:
- Thermal: conductivity, mass heat, stability,
- Mass: sorption isotherms, diffusivity of water vapor or other gases, imbibition monitoring by 2D and 3D X-ray imaging,
- Mechanical: mechanical testing machine positioned in our X-ray tomograph

The extraction of properties from experimental measurements is generally done with the help of simulation codes that allow to consider, at the experimental level, the coupling between properties (multiphysics) and/or the coupling between scales. This allows us to detect and quantify the effects due to local non-equilibrium between phases, very frequent in coupled transfers.