THE RATE OF ISOTHERMAL HEAT EVOLUTION BETWEEN 150-DEGREES-C AND 230-DEGREES-C OF LIGNOCELLULOSIC SHEET MATERIALS IN AN AIR STREAM .1. PRINCIPAL EXPERIMENTAL RESULTS

The rate of isothermal heat evolution in lignocellulosic sheet material was studied at temperatures between 150° and 230°C using a labyrinth air flow calorimeter for 0.9 m long strips of building boards, commercial hardboards, medium density and asphalt-impregnated as well as on laboratory hardboards, of holocellulose, bleached kraft and groundwood, the latter with and without fire retardants. For all boards of mechanical or “thermomechanical” pulp, the rate of isothermal heat evolution after an initiation period was maximum and decreased with reaction time almost according to a first order reaction. For boards of delignified pulp, i.e. of holocellulose and bleached kraft, after an initial constant level the released heat increased with time at temperatures above 200°C whereas it remained almost constant at lower temperature. © 1990, Walter de Gruyter. All rights reserved.