Clay reinforcement flammability

To clarify the mechanisms of the clay-reinforced carbonaceous char formation, which may be responsible for the reduced mass loss rates, and hence the lower flammability of the polymer matrices, a number of thermo-physical characteristics of the PE/MMT nanocomposites have been measured in comparison with those of the pristine PE (which, by itself is not a char former) in both inert and oxidizing atmospheres. The evolution of the thermal and thermal-oxidative degradation processes in these systems was followed dynamically with the aid of TGA and FTIR methods. Proper attention was paid also to the effect of oxygen on the thermal-oxidative stability of PE nanocomposites in their solid state, in both the absence as well as in the presence of an antioxidant. Several sets of experimentally acquired TGA data have provided a basis for accomplishing thorough model-based kinetic analyses of thermal and thermal-oxidative degradation of both pristine PE and PE/MMT nanocomposites prepared in this work. 

Exfoliating layered particles such as the clays, mica, or graphite is being used to provide very effective reinforcement of elastomers at loading levels much smaller than in the case of solid particles such as carbon black and silica [228-231]. Other properties can also be substantially improved, including increased resistance to solvents, and reduced permeability and flammability. 

Polymer clay nanocomposites exhibit very low flammability. For instance, the heat release rate during the combustion of polyamide 6-clay nanocomposite is reduced by 63% with a clay content of 5wt%. The nanocomposite structure also enhances the property of the char through reinforcement of the... 

The flammability behaviour of clay-polymer nanocomposites could be restricted by incorporating the nano-clay as reinforcement in limited volume fraction. The heat release rates also are found to be diminished substantially by nano-clay incorporation. The flammability resistance can be enhanced by the incorporation of nano-clay platelets without compromising other properties [114]. This improvement in flammability resulted in development of Wire Cable jacket material [115]. 

Nanocomposites materials can be defined as composite materials, that combine one or more separate components in order to improve performance properties, for which at least one dimension of the dispersed particles is in the nanometer range [23]. In polymer clay nanocomposites, nanoscale particles have typically 10-100 nm in size [24]. Depending on the reinforcement, remarkable improvement in material properties when compared with neat polymer or conventional micro and macro-composites can be obtained. These improvements can include high moduli, increased strength and heat resistance, decreased gas permeability and flammability, and increased biodegradability of biodegradable polymers [25]. 

Ray, S.S. Thermal stability and flammability of environmentally friendly polymer nanocomposites using biodegradable polymer matrices and clay/carbon nanotube (CNT) reinforcements. Environmentally Friendly Polymer Nanocomposites, pp. 295-327. Woodhead Publishing, Cambridge (2013)... 

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