Carbon nanotubes (CNTs) are attractive flame retardants for polymers because they can be used in low concentrations and can act as a synergist with conventional additives. In the present work, we functionalize multi-wall CNTs (MWCNTs) with phosphorous, a known flame retardant, to prepare phosphorous CNTs (PCNTs). These PCNTs were incorporated into polystyrene (PS) and poly (methyl methacrylate) (PMMA) by solution blending, and the composites’ thermal properties were investigated through thermal gravimetric analysis (TGA) and micro combustion calorimetry (MCC). In PS, the PCNTs were well dispersed and improved thermal stability in proportion to the phosphorus loading, effectively reducing PS flammability. In PMMA, the PCNTs were more aggregated, and they only moderately improved the polymer’s thermal stability by delaying the onset of thermal degradation. Material characterization of the PCNT powders, composites, and TGA residues indicated that PCNT flame retardants primarily act in the condensed phase, encouraging char formation of the dispersed CNT network to protect the underlying polymer. Our results show how targeted functionalization of MWCNT with flame retardant heteroatoms can improve the thermal stability of synthetic polymers when properly dispersed throughout the matrix.

Phosphorous-functionalized multi wall carbon nanotubes as flame retardants for polystyrene and poly (methyl methacrylate)

253rd National Meeting (2017)

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