Functionalisation of multiwalled carbon nanotubes with melamine phosphate and their influence on morphology, thermal stability, flame retardancy and mechanical properties of ABS

Abstract

ABSTRACT Multiwalled carbon nanotubes (MWCNTs) were carboxylated by nitric acid oxidation/plasma pretreatment, and melamine phosphate (MP) was grafted onto the surface of MWCNTs to obtain functionalised MWCNTs-MP. The modified MWCNTs were characterised by FT-IR, Raman spectroscopy, XRD, 1H-NMR, TEM, SEM and TGA. The results proved the successful preparation of MWCNTs-MP. The acrylonitrile–butadiene–styrene copolymer (ABS) composites were prepared by melt blending with MWCNTs-MP and characterised using TGA, microscale combustion calorimeter, limiting oxygen index (LOI), SEM and tests to record mechanical properties. The addition of 1% MWCNTs-MP to ABS improved its thermal stability, reduced combustion parameters and increased its LOI value by 27.8%. This is attributed to the MP grafted onto the surface of the MWCNTs. During combustion, this forms a char layer that acts as a heat transfer barrier. The enhanced mechanical properties of the composite were attributed to the improved dispersion of the modified MWCNTs-MP in ABS.