Synthesis and properties of polyterephthalamides with ester pendent groups

Abstract

3,5‐Dinitrobenzoyl chloride reacted with various alcohols such as phenol, biphenyl‐4‐ol, 1‐naphthol, or diphenylmethanol to afford the 3,5‐dinitrobenzoic acid ester derivatives which were catalytically hydrogenated to the corresponding diamines. The latter reacted with terephthaloyl dichloride to yield a new series of modified polyterephthalamides bearing pendent groups connected to the polymer backbone with ester linkages. The analogous unsubstituted polyterephthalamide were also prepared to compare the properties of the two series of aromatic polyamides. The polyamides were characterized by FT‐IR, 1H‐NMR, inherent viscosity, and water‐absorption measurements, x‐ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The modified polyamides exhibited better solubility in certain organic solvents and higher hydrophilicity than the corresponding unmodified one. They were amorphous and softened at about 230°C. The glass transition temperatures ranged from 178 to 217°C. After an appropriate thermal treatment, crosslinking of modified polyamides was achieved and their thermal stability was slightly lower than that of parent unsubstituted polyamide. They were stable up to 354–370°C in N2 or air and afforded anaerobic char yields of 50–60% at 800°C. © 1996 John Wiley & Sons, Inc.

Compared properties of aromatic polyisophthalamides containing 5-(4-acetoxy-benzamido) pendent groups

“…The initial decomposition temperature of these polymers is in the range of 270–310°C, being comparable with those of aromatic polyisophthalamides reported in the literature 12. The temperature of 10% weight loss ( T 10 ) is in the range of 320–380°C and is about 100°C lower than those of related aramides containing unsubstituted benzamide groups3 and 50°C lower than those of polytherephthalamides containing ester pendent groups 10…”

“…Polyamides with 5‐(4‐acetoxy‐benzamido) pendent groups showed a water uptake of 2.23–2.92% after 72 h exposure time (Table II). These values correspond to those of other similar polyamides that contain esters or amido groups in the pendent chain 10, 11. It is seen that these polymers display a remarkable hydrophilicity probably because the pendent groups cause less dense chain packing, which increases the water accessibility.…”

Synthesis of High Molecular Weight Poly(m-phenylene terephthalamide) in NMP/CaCl2Solvents

“…Thermogravimetric Analysis (TGA): TGA was performed to examine the thermostability of PMTA. As shown in Figure 11, the onset of weight loss by TGA (the point at which the curve deviates from the tangent to the linear/horizontal segment) [32] Figure 12, the Tg was 296 o C, which is higher than that reported elsewhere (238 o C) [4,5]. The Tg of a polymer is dependent on the chemical make-up of the material, and increases with the increasing stiffness of the polymeric segments and molecular weight [32].…”

“…To prepare the NMP solvent, a molecular sieve was placed in the reaction vessel at room temperature [16]. The co-solvent was prepared by combining NMP and CaCl 2 at different concentrations (1,3,5,7, and 9%) were combined by constant stirring at 80 o C for 2 hours under a constant nitrogen flow. The resulting co-solvent was dried over a molecular sieve at room temperature [16].…”

“…Mikroyannidis [4] reported that the polymerization solvent, DMAC with added LiCl, produced PMTA with an inherent viscosity of 0.51 (dl/g, Ubbelohde). Spiliopoulos and Mikroyanidis [5] used pure DMAC as the synthesis solvent, and reported that the final product had an inherent viscosity of 1.55 (dl/g, Ubbelohde). Kardas and Kapuscinska [6] used DMSO and produced a PMTA polymer with an inherent viscosity of 1.11 (dl/g, Cannon-Ubbelohde).…”