Experimental investigation of mechanical properties of binderless particleboards using different biomass materials and pressing conditions

In this thesis the physical and mechanical properties of fully bio-based binderless particleboards made from renewable biomass and agricultural residues are investigated. The panels were manufactured with a Mytrill matrix made from hemp and different natural aggregates such as Giant Reed, bamboo, hemp shives, digestate, flax and hazelnut shells. The study was performed in two experimental phases. In Wave 1, the effect of manufacturing pressure was tested by manufacturing panels at 0.2, 0.5 and 1.0 MPa. Mechanical characterization involved density, internal bond (IB), surface soundness (SS) and three-point bending tests based on EN standards. The results showed that increasing pressure generally improved the density and mechanical performance for all types of material The best overall performance was recorded by C/60 panels made of hemp having the highest density, internal bonding and bending strength among the tested formulations. Wave 2 aimed at optimization of selected hemp- and digestate-based panels by investigating the effects of Mytrill content, fibre length, aggregate type and compaction conditions. Panels were made with different Mytrill to aggregate ratios (40–60%, 60–40%, and 80–20%) using mixed, long and medium fibre configurations, and additional natural fibre reinforcements such as bamboo stems and flax stems. Higher compaction panels (C27 and D27) were also investigated to evaluate the effect of densification on panel behavior. The results revealed that the increase in Mytrill content significantly improved the density, internal bond strength, surface soundness, and bending performance. The best mechanical performance was found for panels made of 80% Mytrill, especially C80L and C80M. The length of fibre also had an impact on the outcome: long fibres helped to improve the load-carrying ability while some configurations with medium fibres showed higher stiffness.