S. Hsiao, Hui-Yu Chang
Jun 1, 1996
Citations
0
Influential Citations
21
Citations
Journal
Journal of Polymer Science Part A
Abstract
The five benzene rings-containing (hereafter referred to as five-ring) dicarboxylic acids α,α'-bis[4-(4-carboxyphenoxy)phenyl]-1,4-diisopropylbenzene (p-III) and α,α'-bis[4-(4-carboxyphenoxy)phenyl]-1,3-diisopropylbenzene (m-III) were prepared by the fluoro-displacement of α,α'-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene and α,α'-bis(4-hydroxyphenyl)-1,3-diisopropylbenzene with p-fluorobenzonitrile, and subsequent alkaline hydrolysis of the intermediate dinitriles. A number of high-molecular-weight polyamides based on these two five-ring dicarboxylic acids (p-III and m-III) and various aromatic diamines were directly synthesized in N-methyl-2-pyrrolidone (NMP) containing lithium chloride (LiCI) or calcium chloride (CaCl 2 ) using triphenyl phosphite and pyridine as condensing agents. These polyamides were obtained with inherent viscosities above 0.51 and up to 0.91 dL/g. The weight-average molecular weight were in the range of 51,000-211,000. Most of these polyamides were amorphous and readily soluble in polar solvents such as NMP, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), and afforded tough, flexible, and transparent films by solution-casting. The films had tensile strength of 50-83 MPa, elongation to break of 4-8%, and tensile modulus of 1.3-2.0 GPa. Most polyamides showed distinct glass transitions on the differential scanning calorimetry (DSC) curves ranging from 147 to 177°C. In nitrogen or air, all the polymers showed no significant weight loss up to 490°C, as indicated by thermogravimetric analysis (TG)