Development and mechanical characterization of a bio-based composite composed of lignosulfonates matrix and corn cob particles

This study aims to establish the proof-of-concept for the development of a bio-based composite made of lignosulfonates (obtained from the sulfite pulping process) and corn cob particles. Indeed, it has been noticed that some French territories such as Auvergne Rhône-Alpes region possess under-exploited woody resource and agronomic by-products. As an example, 2.4 million m3 of non-valorized wood is available in Auvergne per year. Fractionation of this biomass in a biorefinery gives sugars (cellulose, hemicelluloses) but also lignin, a complex natural polymer of phenylpropane units entering at 20-30% in the composition of wood. In this work, raw materials meaning lignosufonates solubilized in water and ground corn cob were mixed, molded, compacted, and
dried. Mechanical strength of obtained composites in compression mode was evaluated with calculation of Young’s modulus (E) and ultimate compressive strength (σmax). The influence of fiber content, fibers particle size, and compaction pressure applied on the composite during processing was investigated with a design of experiments approach. The model enabled to calculate an optimum for σmax around 18 MPa for a corresponding Young’s modulus of 0.27 GPa and a composite density of 993 kg/m3. Particle size was found to be the most influent parameter on mechanical strength responses. Particle sieved between 400 and 500 meshes lead to better σmax of the composite. It was also found that increasing compaction pressure as well as fiber content is in favor of compressive strength.