The time and heat flux required for the initiation of smoldering combustion in cellulosic fabrics depends on the properties of both the environment and the fabric. In the environment, there must be sufficient oxygen to support smoldering combustion and there must be sufficient heat to raise the temperature of the fabric to the point where combustion becomes self supporting. The critical factors for the cellulosic fabrics are the potassium and/or sodium ion content and the thermal characteristics of the fabric. A series of simple weave, raw cotton fabrics, commonly referred to as cotton ducks, and an upholstery fabric were examined. The requirements for the initiation of smoldering combustion were similar for both the ducks and the upholstery fabric. However, the situation for the upholstery fabric was complicated by the non-homogeneous distribution of ions in the material and spatial variations in fabric thickness and basis weight. Also, for fabrics with potassium and sodium ion contents in the range of approximately 1500 to 2500 ppm, there was an increased sensitivity to the environmental factors.

In order to understand how the raw materials and processing contribute to the performance of the products, a mathematical model of pressure drop and ventilation in a lit cigarette has been developed. The model can be used to predict these parameters based on the geometry and properties of tobacco rod and filter, such as cigarette circumference, paper permeability, and design of filter vent rows. The model can be used to evaluate the contributions of variable components to the changes of pressure drop and ventilation of a lit cigarette.

The initiation of fabric smoldering combustion is known to be in fluenced by a heat source and the properties of the fabrics. In order to understand what is most critical to the smoldering ignition of fabric, it is important to develop a predictive model. In the present study, a mathematical model has been devel oped based on the heat transfer mechanism involved in the heating of cotton ducks and upholstery fabrics by vertically and horizontally placed cylindrical car tridge heaters. The reaction kinetics of the cotton pyrolysis and char combustion are considered in the model. The effect of temperature on the material properties and the surface heat transfer coefficient is also taken into account. The integral method is used in solving the governing heat transfer equations. The model pre diction of the temperature history of the fabrics and the time to ignition agrees quite well with the experimental results. The theoretical ignition temperature of fabrics may be defined as the material temperature at which the char combustion becomes dominant. Thus, the ignition temperatures of cotton ducks of different basis weight or treated to various ion content levels can differ.

Cigarette-burning and the smoke-formation processes and smoke composition are important topics for understanding cigarette performance. This paper proposes the molecular formulas representing the active components of bright, burley, and Oriental tobaccos and a basic chemistry model of the cigarette burning processes. Previous knowledge of the cigarette burning processes and smoke formation helped to establish parameters in deriving the basic chemistry equations. The proposed chemistry provides a brief view of the mechanisms of the cigarette burning during puffing and interpuff smoldering, and can be used to interpret and predict the smoke composition for cigarettes made from bright, burley, and Oriental tobaccos. Based on the proposed chemistry, the effect of ventilation on smoke component deliveries is discussed and the reaction heat of the puffing process is estimated.