Grey alder fibreboard processed by modified steam explosion unit
2010
Tupciauskas, R., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Gravitis, J., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Belkova, L., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Tuherm, H., Latvia Univ. of Agriculture, Jelgava (Latvia)
Experimental self-binding high-density fibreboard is produced of the grey alder (Alnus incana L. Moench) steam-exploded fibres without addition of synthetic adhesives. Milled grey alder chips are processed in steam-explosion unit by saturated steam under pressure of 3.2 MPa at temperature of 235 deg C for 1 min in a 0.5 l batch reactor. The steam-exploded fibres are pressed at 160 deg C temperature under 8 MPa pressure for 10 min in three steps. Properties, such as density, swelling in thickness, water absorption, bending strength, modulus of elasticity at bending, and internal bonding strength of the studied fibreboard samples are reported. Differences between the raw milled chippings and the exploded fibres are observed by scanning electron microscope. The study is focused on modified technical options of the steam-explosion unit supplied with two containers receiving different kinds of the exploded biomass farther used to obtain the hot-pressed boards. The cascade of the receivers is explained in a presently pending patent. The self-binding high-density fibreboard samples show the following properties comparable to commercial products: density of at least 1.35 g cmE-3, moisture content of 7.2%, swelling in thickness of 8.1%, water absorption of 3.2%, bending strength of 27 N mmE-2, modulus of elasticity of 6,259 N mmE-2, and internal bonding of 0.92 N mmE-2.
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