Investigation of thermal and tensile properties of poly(benzimidazole-imide) composites incorporating salicylic acid–functionalized multiwalled carbon nanotubes

This work describes a novel aromatic poly(benzimidazole-imide) (PBII) with amino salicylic acid (ASA) segments in the main chain by melt/solid polymerization method under solvent-free conditions and its composites reinforced with ASA-functionalized multiwalled carbon nanotubes (MWCNTs-ASA). The polymer was obtained in high yield with an amorphous morphology, was soluble in various organic solvents, such as N,N′-dimethylacetamide, N,N′-dimethylformamide, N-methyl-2-pyrrolidone, and dimethyl sulfoxide, and could afford flexible and tough film via solution casting. MWCNT-ASA/PBII composite films were also prepared by casting a solution of precursor polymer containing different fractions of MWCNTs-ASA into a thin film (1, 2, and 5 wt%). The cast films exhibited good mechanical properties with tensile strengths of 90.00–128.3 MPa, elongation at break of 4.6–7.9%, and tensile modulus of 1.6–2.9 GPa. They were reasonably stable up to a temperature above 400°C for the PBII and above 450°C for the composites. Structural and morphological evaluation of the composites was carried out by Fourier transform infrared spectroscopy and X-ray diffraction. Dispersion of MWCNT-ASA in the polymer matrix was investigated by field emission scanning and transmission electron microscopy.