SYNTHESIS AND PROPERTIES OF AROMATIC POLYAMIDES BASED ON 4,4'-(1,5-NAPHTHALENEDIOXY)DIBENZOIC ACID

4,4'-(1,5-Naphthalenedioxy) dibenzoic acid (3), a novel aromatic dicar boxylic acid monomer, was prepared by nucleophilic substitution reacti on of 1,5-dihydroxynaphthalene and p-fluorobenzonitrile in N,N-dimethy lformamide (DMF) in the presence of potassium carbonate and subsequent alkaline hydrolysis of the intermediate dinitrile, 4,4'-(1,5-naphthal enendioxy)dibenzonitrile. Using triphenyl phosphite (TPP) and pyridine as condensing agents, a series of novel aromatic polyamides were synt hesized by direct polycondensation of diacid 3 and twelve aromatic dia mines in N-methyl-2-pyrrolidone (NMP) solution containing dissolved ca lcium chloride. The resulting polyamides had inherent viscosities abov e 1,14 and up to 4,45 dL/g. Most of these polyamides are readily solub le in polar solvents, such as NMP, DMF and N,N-dimethylacetamide (DMAc ). Transparent, flexible, and tough films could be cast from their DMA c or NMP solutions. Most of these polymers were amorphous in nature, a s indicated by their wide-angle X-ray diffractograms. Thermogravimetri c analysis (TG) showed that all the polyamides were stable up to 450 d egrees C in both air and nitrogen atmosphere. Most of them revealed a distinct glass transition on the differential scanning calorimetry (DS C) traces in the range of 183-259 degrees C.