A. James Clark School of Engineering
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Item Development of a Semiglobal Reaction Mechanism for the Thermal Decomposition of a Polymer Containing Reactive Flame Retardants: Application to Glass-Fiber-Reinforced Polybutylene Terephthalate Blended with Aluminum Diethyl Phosphinate and Melamine Polyphosphate(MDPI, 2018-10-12) Ding, Yan; Stoliarov, Stanislav I.; Kraemer, Roland H.This work details a methodology for parameterization of the kinetics and thermodynamics of the thermal decomposition of polymers blended with reactive additives. This methodology employs Thermogravimetric Analysis, Differential Scanning Calorimetry, Microscale Combustion Calorimetry, and inverse numerical modeling of these experiments. Blends of glass-fiber-reinforced polybutylene terephthalate (PBT) with aluminum diethyl phosphinate and melamine polyphosphate were used to demonstrate this methodology. These additives represent a potent solution for imparting flame retardancy to PBT. The resulting lumped-species reaction model consisted of a set of first- and second-order (two-component) reactions that defined the rate of gaseous pyrolyzate production. The heats of reaction, heat capacities of the condensed-phase reactants and products, and heats of combustion of the gaseous products were also determined. The model was shown to reproduce all aforementioned experiments with a high degree of detail. The model also captured changes in the material behavior with changes in the additive concentrations. Second-order reactions between the material constituents were found to be necessary to reproduce these changes successfully. The development of such models is an essential milestone toward the intelligent design of flame retardant materials and solid fuels.Item Development of a Semiglobal Reaction Mechanism for the Thermal Decomposition of a Polymer Containing Reactive Flame Retardants: Application to Glass-Fiber-Reinforced Polybutylene Terephthalate Blended with Aluminum Diethyl Phosphinate and Melamine Polyphosphate(MDPI, 2018-09-17) Ding, Yan; Stoliarov, Stanislav I.; Kraemer, Roland H.This work details a methodology for parameterization of the kinetics and thermodynamics of the thermal decomposition of polymers blended with reactive additives. This methodology employs Thermogravimetric Analysis, Differential Scanning Calorimetry, Microscale Combustion Calorimetry, and inverse numerical modeling of these experiments. Blends of glass-fiber-reinforced polybutylene terephthalate (PBT) with aluminum diethyl phosphinate and melamine polyphosphate were used to demonstrate this methodology. These additives represent a potent solution for imparting flame retardancy to PBT. The resulting lumped-species reaction model consisted of a set of first- and second-order (two-component) reactions that defined the rate of gaseous pyrolyzate production. The heats of reaction, heat capacities of the condensed-phase reactants and products, and heats of combustion of the gaseous products were also determined. The model was shown to reproduce all aforementioned experiments with a high degree of detail. The model also captured changes in the material behavior with changes in the additive concentrations. Second-order reactions between the material constituents were found to be necessary to reproduce these changes successfully. The development of such models is an essential milestone toward the intelligent design of flame retardant materials and solid fuels.Item A GENERALIZED METHODOLOGY TO DEVELOP PYROLYSIS MODELS FOR POLYMERIC MATERIALS CONTAINING REACTIVE FLAME RETARDANTS: RELATIONSHIP BETWEEN MATERIAL COMPOSITION AND FLAMMABILITY BEHAVIOR(2018) Ding, Yan; Stoliarov, Stanislav I; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The development of effective flame retardant polymeric materials is of great interest to the fire protection community. To enable intelligent design of flame retardant polymeric materials, it is important to understand the relation between the material composition and the chemical and physical properties that control the fire growth process. This work details a generalized methodology to characterize flame retardant materials for the development of pyrolysis models that relate the fire behavior to material composition. The methodology employs thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry, to measure the sample mass loss, heat required to decompose the sample, and the heat released from the complete combustion of the gaseous products evolved during the sample decomposition, respectively. Through inverse analysis of the milligram-scale experimental measurements using a numerical pyrolysis framework, ThermaKin2Ds, the decomposition kinetics and thermodynamics, and heats of combustion of gaseous pyrolyzate are determined. The chemical interactions between the polymer matrix and flame retardants are characterized by second-order (two-component) reactions. The resulting reaction model reproduces all aforementioned experiments with a high degree of detail as a function of heating rate and captures changes in the decomposition behavior with changes in the flame retardant contents. The methodology also utilizes a new bench-scale controlled atmosphere gasification apparatus to measure mass loss rate (MLR), back surface temperature, and sample shape profile evolution of 7-cm-diameter disk-shaped samples exposed to well-defined radiant heating. Inverse analysis of the bench-scale gasification experimental measurements using ThermaKin2Ds and the developed reaction model yields properties that define heat and mass transport in the pyrolyzing samples. This approach is demonstrated using two sets of materials: glass-fiber-reinforced polyamide 66 blended with red phosphorus and glass-fiber-reinforced polybutylene terephthalate blended with aluminum diethyl phosphinate and melamine polyphosphate. The resulting pyrolysis model is capable of predicting MLR data as a function of material composition and external heating condition. Idealized cone calorimetry simulations are conducted to demonstrate that, when the gas-phase combustion inhibition effect is excluded, aluminum diethyl phosphinate has a relatively minor impact on heat release rate, while the impacts of melamine polyphosphate and red phosphorus are significant.