Influence of twin-screw extrusion pretreatment on the properties of sugarcane bagasse-based materials obtained by thermocompression

Julie Cavailles^1,2, Guadalupe Vaca-Medina¹, Jenny Wu-Tiu-Yen², Laurent Labonne¹, Philippe Evon¹, Jérôme Peydecastaing¹ and Pierre-Yves Pontalier¹

¹Laboratoire de Chimie Agro-industrielle (LCA), Université de Toulouse, INRAE, Toulouse INP, 4 Allée Emile Monso, 31030 Toulouse Cedex 4, France; julie.cavailles@toulouse-inp.fr

²eRcane, La Réunion, Sainte-Clotilde, France

The development of green processes to transform lignocellulosic biomass into energy or high-value added products is widely studied due to current environmental issues. Binderless materials were produced by thermocompression in order to valorize sugarcane bagasse into food containers. The aim of this work was to study the impact of sugarcane bagasse pretreatment by twin-screw extrusion on the properties of these binderless materials. Physical characteristics of untreated sugarcane bagasse and extrudate were compared in terms of particle size, morphology, density and specific surface area. Thermocompression experiments were carried out at 200 °C, 102 MPa for 10 min and the materials obtained with and without pretreatment were compared in relation to their density, flexural properties and water resistance. The materials were characterized by three-point bending tests and by immersion in water at 25 °C for 24 h. The extrudate obtained after pretreatment of sugarcane bagasse showed individualized fibers due to defibration and small particles due to the reduction in particle size induced by the thermomechanical action of twin-screw extrusion. Materials obtained from the extrudate exhibited better properties than materials made from untreated bagasse: mechanical properties were twice as high after pretreatment, reaching a flexural strength and a flexural modulus of 55.5 MPa and 5.3 GPa, respectively, while water absorption (WA) and thickness swelling (TS) were halved with a WA of 43% and a TS of 44%. The shaping of 3D materials by thermocompression of bagasse into prototype food containers was facilitated by the use of the extrudate compared to untreated bagasse. These results showed that extrusion pretreatment allowed sugarcane bagasse to be individualized into single fibers contributing to the improvement of the final materials properties by the increase in accessible surface and a reorganization of the fibers during thermocompression.