CONTRIBUTION TO THE SHORT-TERM STRENGTH AND LONG-TERM BEHAVIOR OF MDF OF THE 1ST GENERATION

Characteristic features of MDF of the first generation are: manufacture of MDF from inferior wood assortments with bark, multilayer structure of the boards on fibrous materials of different fineness, gluing of the fibrous material in mixers, lower middle density. Typical properties of these MDF: density 700-730 kg/m3, internal bond 0.50-0.65 N/mm2, bending strength 26-35 N/mm2, modulus E(b) 2700-3000 N/mm2. Dealt with are results from former long-term tests in comparison with conventional particle boards for furniture (of lower bending strength). With constant load not graded according to the strength the deflection of these MDF was similar to, or higher than that of the particle boards, their creeping coefficient exceeded that of the particle boards.