PREPARATION OF POLYAMIDES CONTAINING PARA-LINKED DIMETHYLBIPHENYLENE MOIETIES

A series of wholly aromatic polyamides containing 3,3'-dimethylbipheny l-4,4'-dicarboxylic acid (P-DMBA) and 3,4'-dimethylbiphenyl-4,3'-dicar boxylic acid (Q-DMBA) was prepared by the direct polycondensation meth od using triphenylphosphite and pyridine. Most of the polymers are rea dily soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP), N,N'-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), pyrid ine (py), and m-cresol and could be cast into tough and flexible films . The solubilities of copolyamides containing P-DMBA and Q-DMBA as aci d components were remarkably improved. These were characterized by inh erent viscosity, differential scanning calorimetry(DSC), thermogravime tric analysis (TGA), and dynamic mechanical spectrometry (DMS) measure ments. The glass transition temperatures of these polymers were in the range of 200-300 degrees C and the 5% weight loss temperatures were 4 30-470 degrees C. Films prepared by casting from polymer solutions exh ibited good tensile properties. (C) 1998 John Wiley & Sons, Inc.