Polyimide/organo‐montmorillonite nanocomposites: A comparative study of the organoclays modified with aromatic diamines

Abstract

Six organophilic clays have been obtained through cation‐exchange between sodium montmorillonite (Na +‐ Mt) and the hydrochloride salts of aromatic diamines (DA1–6). The results obtained by thermogravimetric analysis (TGA) showed that the organophilic clays start to decomposition within 150–340°C, which shows that they are thermally stable compared with conventional montmorillonite modified with aliphatic long‐chain quaternary alkyl ammonium salts. The highest thermal stability and interlayer basal spacing were observed for the organoclay obtained from 3,3′‐sulfonyl dianiline (DA2), and therefore it was chosen for preparing clay/polymer nanocomposite materials (CPN). Polyimide/clay nanocomposite materials consisting of benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride (BTDA) and 2‐(5‐(3,5‐diaminophenyl)‐1,3,4‐oxadiazole‐2‐yl)pyridine (POBD) were also obtained by an in situ polymerization reaction through a thermal imidization. DA2‐Mt was used as filler at different concentrations. Both the thermal stability and the glass transition temperature ( T g ) are increased with respect to pure polyimide (PI) at low clay loadings. At high clay concentrations, the organoclay particles make aggregate and as results of this phenomena T g and thermal stability are decreased. POLYM. COMPOS., 36:613–622, 2015. © 2014 Society of Plastics Engineers