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Construction particleboards made from rapeseed straw glued with hybrid pMDI/PF resin

Dukarska, Dorota, Czarnecki, Rafał, Dziurka, Dorota, Mirski, Radosław
European journal of wood and wood products 2017 v.75 no.2 pp. 175-184
buildings, construction materials, desorption, insulating materials, manufacturing, modulus of elasticity, modulus of rupture, particleboards, rapeseed, relative humidity, resins, soaking, straw, vapors
The paper investigates the possibility of manufacturing rapeseed particleboards (RPB) which could be used as construction material in eco buildings. Therefore, single-layer particleboards were produced from rapeseed straw particles glued with mixture of 4.4′-methylenediphenyl isocyanate (pMDI) and phenol–formaldehyde (PF) resins in the weight ratio 70:30 (hybrid pMDI/PF resin). The boards were manufactured with density of 650, 600, 550, 500 and 450 kg/m³. Next, their physico-mechanical properties were determined, i.e. modulus of rupture, modulus of elasticity, internal bond and internal bond after the boil test (V-100) and thickness swelling after 24 h soaking in water. The thermal conduction coefficient (λ) and sorption properties in changeable relative humidity conditions were also determined. Based on the obtained results, it was found that rapeseed straw may be a valuable material used in the production of construction particleboards which meet high strength requirements. Boards with density of 650 kg/m³ meet the requirements of EN 312 standard for type P7 boards. It is also possible to decrease their density to 600 kg/m³ (type P5 boards) and even 550 kg/m³ (type P3 boards). However, rapeseed particleboards are characterized by relatively high values of thickness swelling after 24 h of soaking in water. The weaker resistance to humidity has also been confirmed by tests on sorption and desorption of vapour in changeable relative humidity conditions. Nonetheless, an important advantage of these boards is the fact that they are characterized by better thermal insulation than particleboards.