Effect of structure on properties of aromatic polyamides

Abstract

SynopsisPolyamides 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.

High‐optical transparency and low‐dielectric constant of new organosoluble polyamides containing trifluoromethyl and xanthene groups

“…In addition, the extent of donor–acceptor complex formation could also be further reduced by the lowering of the degree of charge separation along the polymer chain through the introduction of electron‐withdrawing trifluoromethyl groups into the substituted aromatic rings of the diamine. This reduced the charge build up on these aromatic rings resulting from electron donation by the adjacent nitrogen atoms and also removed extensive electronic conjugations 38…”

“…This reduced the charge build up on these aromatic rings resulting from electron donation by the adjacent nitrogen atoms and also removed extensive electronic conjugations. 38 Comparing polyamide 4a with 4a 0 without trifluoromethyl groups, 29 as shown in Figure 5, polyamide 4a exhibited a cut-off wavelength at 325 nm, 20 nm lower than that of polyamide 4a 0 (345 nm), which was attributed to the presence of trifluoromethyl substituents in the polymer backbone.…”

Synthesis and studies of thermal, mechanical and electrical properties of MWCNT-cyclodextrin as a nanoparticle in polyamide matrix based on 2,2-Bis[4-(4-aminophenoxy)phenyl] propane

“…[11,12] There are important factors affecting the product in the polycondensation including equivalence and high purity of the reactants, as well as temperature and time of the reaction. [13] Modification of PA by increasing the solubility and lowering the transition temperatures while retaining thermal stability is of particular interest. Incorporation of an aliphatic unit and copolycondensation can improve the properties of PA.…”

Investigating properties of poly (ether‐amide)/MWCNT nanocomposite films containing 2,7‐bis(4‐aminophenoxy)naphthalene and isophthalic segments

“…The thermodynamic interactions with polymer components may most probably originate from the oxygen containing groups. These may include hydrogen bonding and possibility of wide range of effective noncovalent and covalent modifications . The stronger the intermolecular bond interactions are, the greater the thermal properties would be.…”