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Synthesis and properties of polyamides derived from systematically halogenated terephthalic acids with fluorine, chlorine, or bromine atoms

1988; Wiley; Volume: 26; Issue: 1 Linguagem: Inglês

10.1002/pola.1988.080260123

1099-0518

Minoru Nagata, Naoto Tsutsumi, Tsuyoshi Kiyotsukuri,

Polymer crystallization and properties

Abstract Aromatic polyamides were prepared from systematically halogenated terephthalic acids with hexamethylene diamine, piperazine, 4,4′‐diaminodiphenylether and p ‐phenylene diamine by interfacial or low temperature solution polycondensation. The halogenated terephthalic acids used have mono‐, di‐, or tetra‐substituted fluorine, chlorine, or bromine atoms on the benzene ring. The nonhalogenated terephthalic acid was also used for the comparison. The effects of halogen substitution on the benzene ring on the synthesis and some properties of polymers were examined. Reduced specific viscosity decreased in the order F > Cl > Br by halogen substitution. The incorporation of halogen substituents on the ring led to a decrease of crystallinity and fluoro‐substituents hindered the crystallization more strongly. The melting point ( T m ) decreased in the order F > Cl > Br by mono‐substitution, and Br > Cl > F by di‐and tetra‐substitution. The change of T m caused by the difference of the number of halogen substituents differed depending on the rigidity of polymer chains. The flame‐retardancy estimated by thermogravimetry, self‐ignition, and flash‐ignition test increased with increasing halogen content of the polymers. Solubility increased remarkably by halogen substitution. The peak temperature of tan δ decreased by halogen substitution. Some discussion was made on these effects of halogen substitution.