The aim of this study was to produce binderless materials by thermocompression from lignocellulosic biomass pretreated using twin-screw extrusion. The impact of twin-screw extrusion pretreatment on sugarcane bagasse (SCB) was evaluated, along with the effects of two associated parameters: the liquid-to-solid (L/S) ratio and the screw profile, using three different mechanical shear rates. It was shown that twin-screw extrusion pretreatment resulted in materials with improved properties as compared to those obtained with untreated SCB. The mechanical properties and water resistance of materials obtained after pretreatment were mainly impacted by the screw profile. The flexural modulus increased from 5.3 to 6.1GPa and the flexural strength from 39.0 to 55.5 MPa. Water absorption (WA) from the thermocompressed materials ranged from 25 to 62 %, and thickness swelling (TS) from 24 to 67 %. Materials obtained with a 0.4 L/S ratio had lower flexural strength but the best water resistance. For the same L/S ratio, the use of a more shearing screw profile improved the material properties, especially the water resistance. The best material was produced with pretreated SCB using a 1.25 L/S ratio with the most restrictive screw profile, resulting in materials with a 5.6GPa flexural modulus, 55.5 MPa flexural strength, and WA and TS values of 44 % and 42 %, respectively.

The aim of this study was to assess the influence of thermocompression conditions on lignocellulosic biomass such as sugarcane bagasse (SCB) in the production of 100% binderless bio-based materials. Five parameters were investigated: pressure applied (7-102 MPa), molding temperature (60-240°C), molding time (5-30 min), fiber/fine particle ratio (0/100-100/0) and moisture content (0-20%). These parameters affected the properties and chemical composition of the materials. The density ranged from 1198 to 1507 kg/m3, the flexural modulus from 0.9 to 6.9 GPa and the flexural strength at breaking point from 6.1 to 43.6 MPa. Water absorption (WA) and thickness swelling (TS) respectively ranged from 21% to 240% and from 9% to 208%. Higher mechanical properties were obtained using SCB with fine particles, low moisture content (4-10%), high temperature (≥ 200°C) and pressure (≥ 68 MPa), while water resistance was improved using more severe thermocompression conditions with the highest temperature (240°C) and time (30 min) or a higher moisture content (≥ 12.5%). Correlations were noted between the mechanical properties and density, while the material obtained with only fine particles had the highest mechanical properties and density. Material obtained with a 30 min molding time had the lowest WA and TS due to internal chemical reorganization followed by hemicellulose hydrolysis into water-soluble extractables.