Maya DIAKITE, PhD student specialized in the study of the plant wall of hemp wood, member of the T&A research unit, validated her PhD thesis following her defense on Tuesday, November 29, 2022, which took place in Rouen.

His work was about the "Influence of the parameters of transformation processes undergone by the vegetable matter: focus on the functionalities brought by the temperature and the pH".

The whole UniLaSalle team congratulates Maya for obtaining her thesis!

Abstract

The construction sector currently represents 44 of the energy consumed in France. Each year, this sector emits more than 123 million tons of CO 2 (Ministry of Ecological Transition, 2017 data) and is the source of 50 of the exploited resources.

The current issues in terms of pollution are giving rise to a collective awareness around our consumption habits. The improvement of building materials would increase their physical properties (thermal and acoustic) while limiting the environmental impact and improving air quality. Thus, current research work focuses on improving building materials by incorporating plant particles such as shives, flax shives or sunflower pith for example, Molecules such as monosaccharides from pectins and hemicellulose or polyphenols are highly released during the formulation processes of unbonded particleboard or agro-sourced mortars. These compounds or extractables can alter the setting time of the mortar or induce inter-particle interactions in the unbonded particleboard

The first part of this study deals with the characterization of the plant material. All the physical, chemical and microscopic analyses carried out concern two varieties of chenevotte Ch 1 and Ch 2, one of which (Ch 1) is problematic in the formulation of agro-sourced mortars.
The extractives obtained in the two simulations, mainly composed of monosaccharides and polyphenols, are respectively determined by chromatography and by the use of a temperature sensor, A sequential extraction is also carried out to extract hemicellulose and pectins and to characterize them by infrared An experimental planning (Taguchi method) is finally set up in order to follow, during the preparation phase of an agro-sourced mortar or a particleboard, the chemical modifications undergone by the extractables according to the pH and the temperature.

The main issue of this study is the use of a highly variable agricultural co-product for applications in standardized construction materials. A better understanding of this plant raw material and its extractives as well as the reactions occurring during the valorization of this renewable material in an agro sourced material is thus necessary to improve the quality of the finished product.