Exfoliated and intercalated polyamide-imide nanocomposites with montmorillonite

Polyamide-imide (PAI) is a high performance condensation polymer, which has high heat resistance and high radiation resistance. Solvent suspensions of PAI are widely used in magnetic wire coatings. Montmorillonite (MMT) nanocomposites were investigated for the concentration effects on dispersion, glass transition, degradation, and mechanical properties. Samples were prepared using a controlled torque stirrer and slow solvent extraction was followed for the cast samples. Optical microscopy shows that the surface of the cast sample has increased edge-edge clay platelet attraction. Transmission electron microscopy of the through thickness sample indicated platelet edges, increased face-face coagulated states and some edge-edge flocculated states of tactoid formation. X-ray diffraction indicated that for 1% sample a highly exfoliated structure was obtained while between 1.5 and 3% intercalated and exfoliated dispersions were obtained. The glass transition was not significantly affected by clay presence but a drop in specific heat change was observed for all samples showing a 001 clay peak presence. The first heating scan showed PAI solvent and MMT organic emission but these emissions did not affect the PAI chemically. Degradation was altered by the level of matrix shielding by the clay. Hardness values were increased with clay presence but unaffected by concentration. (C) 2002 Elsevier Science Ltd. All rights reserved.