Thermal, Mechanical and Flammability Studies of Flame-retardant Polymer Nanocomposites
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Date
2018-03-23
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Abstract
Polymers are widely used in our day-to-day lives and we are often oblivious to the fire hazard imposed by these hydrocarbon-based materials. The current study introduces the application of fire retardant nanofillers for enhanced flame retardancy as a potential remedy against flame spread. With the objective of understanding how the flame retardant nanofillers work; the thermal, mechanical and fire reaction properties have been investigated. For this purpose, neat polystyrene (PS), PS-silica and PS-montmorillonite (MMT) have been prepared via in-situ polymerization method. The thermal degradation mechanism of the neat polymer and polymer nanocomposites and the effect of nanoparticle loading on thermal properties have been investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) equipment. TGA and corresponding derivative TG (DTG) results show that there has been improvement in thermal stability for the nanocomposites in terms of higher onset temperature of degradation and 72-87% more char yield with respect to neat PS. The mechanical test revealed that increased loading reduces hardness for the nanocomposites compared to the neat polystyrene.
To obtain the full scenario of the performance of the flame-retardant polymer nanocomposite system, it is important to explore the aspect of a real fire scenario in cone calorimeter. According to the fire reaction properties as measured in the cone calorimeter, both neat polystyrene and polystyrene nanocomposites have shown the trend of a thermally thick charring polymer in the heat release rate over time data. The nanocomposites had an overall better flame retardancy than the neat polystyrene in terms of lower peak heat release rate, lower average mass loss rate and enhanced char formation. The nanocomposites had also reduced smoke emission with lower CO and CO2 yield compared to the neat polystyrene.
It was concluded that the addition of nanosilica and nanoclay in small loading can significantly improve thermal stability, fire reaction properties and mechanical properties; however, higher loading may result in agglomeration and reduction in hardness.
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flame retardancy, polymer nanocomposites, thermal, mechanical, flammability