Mechanical and electrical properties of some silicon-containing poly(amide-imide)s

Aromatic silicon-containing poly(amide-imide) s have been prepared by low temperature solution polycondensation reaction of various aromatic diamines having ether bridges between phenylene rings with a diacid chloride, namely bis[N-(4-chlorocarbonylphenyl) phthalimidyl] dimethylsilane. These polymers were easily soluble in polar amidic solvents such as N- methylpyrrolidone, N,N-dimethylacetamide, and N, N- dimethylformamide and can be cast from solutions into thin, flexible films. They showed good thermal stability, with initial decomposition temperature being above 410 degrees C and glass transition temperature in the range of 263-285 degrees C. The polymer films exhibited good mechanical properties with tensile strengths in the range of 78-109 MPa, tensile modulus in the range of 1.44-1.76 GPa, and elongation at break values ranging from 11% to 24%. Electrical insulating properties of two polymer films were evaluated on the basis of dielectric constant and dielectric loss and their variation with frequency and temperature.