New thermally stable nanocomposites reinforced silicate nanoparticles containing phosphine oxide moiety based on poly(amide-imide): synthesis, characterization and flame retardancy study

New type of nanocomposite materials were produced using a poly(amide-imide) (PAI) matrix and novel organoclay as a reinforcing agent by solution intercalation technique in N-methyl-2-pyrrolidone (NMP). The organoclay was prepared from Cloisite Na+ and protonated form of bis(3-amino phenyl)phenyl phosphine oxide via ion-exchange reaction. It was confirmed by Fourier transform infrared spectroscopy and X-ray powder diffraction techniques. A new PAI containing phenylacetic acid moiety was synthesized by direct polycondensation reaction of 2,2′-(5,5′-oxybis(1,3-dioxoisoindoline-5,2-diyl))bis(2-phenylacetic acid) as a new diacid and 4,4′-diaminodiphenylsulfone. Poly(amide-imide)/nanocomposites (PAIN)s containing 4 and 8 % of new organoclay were prepared via solution intercalation method through blending of organoclay with the PAI solution. The nanostructures and properties of the PAINs were investigated using different techniques. Transmission electron microscopy and XRD results revealed the good dispersion nano silicate layers in the polymer matrix. Thermal properties and flame retardancy of the resulting PAINs were investigated by thermal gravimetry analyses and microscale combustion calorimetry techniques. Organoclay shows a good effect on improving the flame retardancy of the PAI, reflecting the decrease in heat release rate (HRR) from 250 W/g for PAI to 185 and 157 W/g for PAINs, while the thermal stability of the PAI nanocomposites only increased slightly compared to the neat polymer.