Preparation and properties of aromatic polyamide homologs containing chlorine substituents

Abstract

In order to study systematically the effect of halogen substituents on both the solubility and the thermal stability of aromatic polyamides, new diamine monomers have been synthesized by introducing chlorine groups onto various positions of 4,4′‐diaminobenzanilide for the preparation of chlorinated aromatic polyamides. The monochlorinated aromatic polyamides, i.e., P‐LCl and P‐RCl, exhibited liquid crystalline property in 100% sulfuric acid solution in the temperature range from 40 and 60°C. However, the dichlorinated sample, i.e. P‐LRCl, did not exhibit the liquid crystalline property due to the bulkiness of two chlorine groups. Both P‐LCl and P‐RCl exhibited unimodal decomposition behavior in contrast to the chlorinated poly(p‐phenylene terephthalamide) (PPTA) that has been known to show bimodal decomposition behavior. The decomposition onset temperature of both P‐LCl and P‐RCl was 567°C, which was higher than 549°C of unchlorinated polyamide, P‐NCl, but the same as that of PPTA. The char yield was about 50% for both P‐LCl and P‐RCl and higher than 40% of both PPTA and P‐NCl. In the case of P‐LRCl, the decomposition onset temperature was 480°C, but the highest char yield of 60% was obtained. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1387–1392, 2000

Mechanochemical Decomposition of an Aromatic Polyamide Film

“…Because of its excellent chemical, mechanical, and thermal properties, the film has come to be widely used in various fields. In some aramid products, hydrogen is substituted by other elements such as chlorine to improve their thermal and physical properties, allowing its use for solar cells, magnetic recording tape, special thin belts, electronic parts, and the like. − When the aramid goods are to be disposed of, it is not always easy to decompose them because of their chemically stable properties. As is well-known, combustion operations of such wastes without controlling the temperature have been facing strong public opposition at present because of the possible formation of toxic substances such as dioxins like polychlorinated dibenzo- p -dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs).…”

Simple Synthesis of Hydroxyl and Ethylene Functionalized Aromatic Polyamides as Sizing Agents to Improve Adhesion Properties of Aramid Fiber/Vinyl Epoxy Composites

“…PPTA is difficult to dissolve in any organic solvents, chemical modification of PPTA is a plausible method to improve the polymer solubility. It has been suggested that the introduction of halogen groups onto the aromatic polyamide is an effective method to improve the solubility of the polymer [30]. HTBN not only can be used as adhesives for rubber, polyester and metal, but also as a toughening agent for the modification of epoxy resin [31].…”