EFFECTS OF PRESSING PRESSURE AND KRAFT LIGNIN ADDITION IN THE PRODUCTION OF BINDERLESS FIBERBOARD FROM STEAM EXPLODED Gynerium sagittatum

Gynerium sagittatum is a grass that has great ecological adaptability, which makes it an ideal lignocellulosic source for the manufacture of fiberboards. The effects of pressing pressure and the addition of kraft lignin on the physicomechanical properties of high density fiberboards of Gynerium sagittatum are evaluated. The raw material is pretreated in a steam explosion reactor at severity 4,1. The pressing temperature is set at 217 degrees C. The pressing pressure is varied between 2 and 15 MPa. The most appropriate pressing pressure to obtain a good quality boards is 2 MPa. The values of properties at optimal conditions are: modulus of elasticity 6000 MPa, modulus of rupture 47 MPa, internal bond 1,50 MPa 24 h water absorption 25% and 24 h thickness swelling 15%. Based on these operating conditions, the inclusion of lignin between 0 and 30% is evaluated. The addition of lignin does not significantly affect the mechanical performance of the fiberboards but improve its dimensional stability. The obtained values for 24 h water absorption and 24 h thickness swelling are 19% and 8,5% respectively, at a 20% of lignin addition.