Fibers of secondary ligno-cellulose materials and their influence on properties of insulating fiberboards

This paper deals with the influence of addition of abraded fiber, as a partial substitute of softwood fibers, on the properties of insulating fiberboard. The fiber used was characterized by fractional composition of fiber length according to McNett (STN 50 0289) using the apparatus for the measurement of fiber length in aqueous suspension (ADV) and according to Brecht-Holl (STN 50 0289) by the determination of water retained by fiber, speed of dewatering and defibrator seconds. Insulating fiberboards were prepared with different content of abraded fiber. Mechanical properties (bending strength and tension strength perpendicular to the board plane) as well as physical properties (swelling, water uptake, thermal conductivity, thermal diffusivity specific heat and volumetric specific heat) were measured for the boards.