Effect of structure on properties of aromatic polyamides

✍ Scribed by I. K. Varma; Ramakant Kumar; A. B. Bhattacharyya

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 442 KB
• Volume: 40
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1990.070400319

✦ Synopsis

Polyamides were prepared by reacting 3,5-diamino benzoic acid (DAB) and/or 1,3-bis( 3-amino benzamido) benzene ( ABB ) with terephthaloyl chloride in N,N-dimethylacetamide. Five polymer samples having different contents of pendant carboxyl groups were prepared by changing the molar ratios of DAB : ABB in the initial monomer feed as 1 : 0 ( C ) , 3 : 1 ( C3A), 1 : 1 (CA) , 1 : 3 ( CA3), and 0 : 1 (A). The inherent viscosities of the polymers ranged from 0.198 to 0.478 dL/g. DSC and TG studies indicated loss in weight in the temperature range of 80-200°C due to absorbed moisture.

The major loss in weight was observed above 400°C. The anaerobic char yield a t 800°C depended on the backbone structure and was found to range from 25 to 40%. The resistivities of polyamide film was determined a t 110 and 130°C and was found to decrease with an increase in carboxyl content. The dielectric constant of C and C3A polymer films was determined at frequencies ranging from 100 Hz to 1 MHz and at 110 and 130°C and was found to decrease with an increase in frequency or decrease in COOH content in the backbone.