Study of Selected Natural Materials Ignitability

Abstract

This scientific study deals with a complex research of initiation process of selected natural materials. The first chapter deals with research of the influence of density and thermal modification of spruce wood (Picea abies(L.) Karst.) on the critical heat flux density for the pilot ignition. In this chapter the thermally modified and unmodified samples of a spruce wood were investigated. The thermally modified samples were prepared according to temperature program for the ThermoWood - Thermo-S (maximum temperature during the thermal modification was 190 °C) and ThermoWood - Thermo-D (the maximum temperature during the thermal modification was 212 °C) production. Critical density of heat flux was determined on a cone calorimeter test by procedures in accordance with ISO 5660-1:2002. The obtained results showed that the thermally modified spruce wood in comparison with the thermally unmodified one had higher critical density of heat flux. The second chapter is aimed on determination of ignition activation energy of pure cellulose, cellulose impregnated by water solutions of KHCO3and (NH4)2HPO4with concentrations of 5, 10 and 15 wt. % and on determination of ignition activation energy of dust from beech wood (Fagus sylvaticaL.). The activation energies were determined in accordance with isothermal, dynamic and non-isothermal model-free methods. The obtained results showed that the ignition activation energy of cellulose impregnated by water solutions of KHCO3and (NH4)2HPO4have lower activation energy than the pure cellulose. The obtained data on the activation energy of beech wood dust showed that the activation energy depends significantly on the degree of conversion. Chapter three deals with the research of inclination of selected vegetable oils (Linseed, Sesame and Sunflower oil) applied to cotton to self-ignite. The propensity towards spontaneous combustion of the mentioned oils was investigated by Mackey test and Accelerating Rate Calorimetry. The results showed that the ratios of oil mass to the mass of the carrier, on which oil is applied, had significant impact on the propensity of vegetable oil to the spontaneous combustion. The highest propensity to spontaneous combustion of the investigated materials showed the Linseed oil.