Sharif Digital Repository

A mixture of a fuel and an oxidant can give rise to a self-propagating flame if the oxidant/fuel ratio is within a specific range. The boundaries of this range are called explosive limits. Lower explosive limit (LEL)—defined as the least fuel concentration capable of self-propagating a flame—and upper explosive limit (UEL)—defined as the greatest fuel concentration capable of self-propagating a flame—are properties of a fuel-oxidizer mixture. These limits are important aspects of burning. It is not possible for flame to propagate out of these ranges. The values of these limits are necessary to prevent accidental explosions during chemical processes. In this work, a direct use of group... 

Today, in many industries polypropylene is used as a polyolefin with favorable properties such as chemical resistance, fatigue strength, electrical insulation, as well as good mechanical properties such as high Yang modulus, good toughness, and so on. On the other hand, polyolefins have poor thermal resistance and high flammability. Over the years, many researchers have been working to reduce their flammability through different methods and increase their thermal resistance. Among these methods, adding materials that delayed flammability or stoped it, can be noted. In the industry, these anti-flammable additives are called flame retardants. Flame retardant additives should be selected to... 

Polycarbonate (PC) is known as one of the engineering plastics with remarkable mechanical properties, but the application of this polymer is limited due to its high notch sensitivity. Blending polycarbonate with other polymers such as acrylonitrile butadiene styrene (ABS) is a method to resolve this disadvantage. PC/ABS blends are commonly used in automotive industry, electrical and electronic devices. As PC and ABS are not completely miscible, a variety of compatibilizers are used to achieve a suitable microstructure and high engineering properties. Considering crucial applications of PC/ABS blends, different flame retardants are also used to reduce the flammability. These flame retardants... 

In this work, we establish the constancy of expansion ratio (density factor) and adiabatic flame temperature for predicting lower explosive limits and further establish the constancy of expansion ratio for measuring upper explosion limits. Flammability limits are important characteristics of combustion processes. The flame can only propagate in a specific range of ratios of concentration of fuel to oxidant. The maximum of this concentration ratio that make possible propagation of flame in a mixture, is called upper flammability limit. The minimum of this ratio that make flame propagation possible is called lower flammability limit. Limits of flammability change with initial conditions such... 

A significant portion of the substances used in the chemical industry are toxic and hazardous, posing major safety hazards. In this regard, studies on the flammability limits of flammable materials are important and necessary. Flammability limits are the range of fuel-oxidant mixtures that can lead to flame propagation. This project examines the flammability limits of different fuels. In this study, a set of fuels have been selected as the fuel world, and to select these compounds, their molecular structure as well as thermodynamic properties such as standard enthalpy of formation and standard enthalpy of combustion have been considered. It has been shown that by redefining the fuel world,...