The wood-based MDF-standard (EN 622-5: 2006) requires
a TS level below 30% for fibreboard thicknesses between 4
and 6mm and a TS below 17% for thicknesses between 6 and 9mm. Fibreboards treated with CaCl2 and 4% hydrogen peroxide
(trial RB) showed approximately 80–100% swelling in the
density range 950–1000 kg/m3. The WABS of produced straw
fibreboards was estimated at 110–130%. The water-repelling
properties improved at higher densities. Increased loadings
of hydrogen peroxide and the addition of calcium chloride
reduced the thickness swelling by approximately 25%. The
lowest thickness swelling and water absorption properties
were achieved with the reference SMDF composed of wheat
straw, UMF resin and wax.