Effect of enzymatic treatment (endo-glucanases) of fiber and mechanical lignocellulose nanofibers addition on physical and mechanical properties of binderless high-density fiberboards made from wheat straw

Abstract

Fiberboards are used in a variety of applications that can be for interior as well as for exterior. However, their production involves the consumption of virgin wood fibers and the use and production of formaldehyde-based adhesives, with the consequent impact on the environment and health. The removal of these adhesives results in a significant loss of physico-mechanical properties. To confront these major problems, the use of wheat straw, an agricultural waste, as raw material for the production of binderless fiberboards has been explored. As an alternative to synthetic adhesive, enzymatic treatment of fiber and lignocellulose nanofibers (LCNFs) addition, as well as their combination, have been studied. The different treatments produce an important increase in the mechanical properties in front of the untreated fiber and commercial fiberboard, being the combination of both which presents the best results. Separately, the enzymatic treatment produces a greater strengthening effect than the addition of LCNF. In terms of structural stability, the addition of LCNFs and treatment combinations shows the best results for water absorption and thickness swelling. The results obtained show the possibility to obtain fiberboards without synthetic adhesives with mechanical properties far superior to commercial fiberboardsas as such as bending strengths higher than 100 MPa, flexural modulus 5.5 GPa, internal bond 1.6 MPa, and 122.52 kJ/m2 of impact strength with an estimated added cost of 1 /m3