Polyamides from 1,4-cyclohexanebis(ethylamine) and aliphatic dicarboxylic acids

Abstract

synopsisA homologous polyamide series of 1,4cyclohexanebis(ethylamine) (CBEA) was prepared with Cg to Clz linear, aliphatic dicarboxylic acids. Polymer and fiber properties were found to be quite dependent upon the cis and trans structure of the cycloaliphatic ring. Polyamides based on trans-l,.Q-CBEA had higher melting and higher glass transition temperatures than their cis analogs. In addition, trans polyamides were quite crystalline, whereas the cis polymers were almost completely amorphous. The boiling water shrinkage, tenacity, and moisture regain of the fibers reflected the differences in molecular fit between the cis and trans polyamides. INTRODUCTIONPolyamides containing cyclohexylene linkages have not been studied as extensively as those with phenylene linkages. Moreover, the influence of the cyclohexane ring upon polymer and fiber properties is complicated by the existence of cis and trans isomers. Interconversion of these isomeric forms can occur during melt polymerization, which dictates careful selection of intermediate materials and analysis of polymeric products. Isomerization of cis to trans structure during thermal polymerization has been reported to occur where the carboxyl group is joined directly to the cyclohexane ring.''2 Carboxyl groups separated from the ring by a methylene linkage do not cause isomerization under thermal polyc~ndensation,~ nor do amino groups, whether attached to the ring4 or separated by a methylene link.5Investigations of the cyclohexylene linkage have been concentrated primarily upon the development of heat-resistant, fibers, most of which employed cyclohexane amino acids as the starting monomer. Polyamides prepared from simple cycloaliphatic diacids and diamines have been limited primarily to diaminocy~lohexane,~~~ hexahydrophthalic acids, 1*7 and 1,4-cyclohexanebis(methylamine) .5 Unfortunately, many polyamides based on these materials are unsuitable for melt polymerization because the polymer melting points are too high.Most studies of cyclohexylene polyamide properties have been limited to melting point, solubility, or thermal stability. While such data are quite valuable, a broader investigation of structure-property relationships would be helpful.

Melting behavior of polyamides prepared from isomeric 1,4‐, 1,3‐ and 1,2‐cyclohexanebis (alkylamines)

“…Materials CBEA has been previously described (3). The intermediates, 1,2-CBEA and 173-CBMA, were prepared in similar fashion by catalytic hydrogenation of o-bi@-aminoethyl) benzene (synthesized by a Raney cobalt catalyzed reduction of o-xylylene dinitrile) and m-xylylene diamine (obtained from commercial sources).…”

“…The intermediates, 1,2-CBEA and 173-CBMA, were prepared in similar fashion by catalytic hydrogenation of o-bi@-aminoethyl) benzene (synthesized by a Raney cobalt catalyzed reduction of o-xylylene dinitrile) and m-xylylene diamine (obtained from commercial sources). scribed (3). Separation of the cis and trans isomers was achieved by fractional crystallization.…”

“…Polymerization. The polyadipamides of 1 ,4-CBEA, t-l,3€BMA, and c-l,3-CBMA were prepared by melt polymerization (3) and spun into fibers, which were drawn to approximately five times therir original length over a 60-90°C hot pin.…”

“…Studies of polyamides prepared from cyclohexanebis(alky1amines) have been principally concerned with the 1,4cyclohexylene linkage (1)(2)(3)(4), although limited data have been reported for polyamides from 1,3-~yclohexanebis(methylamine) (5) and 1,2-~yclohexanebis(ethylamine) (6). However, little information is available which relates the effects of both positional and geometrical isomerism in polyamides containing the cyclohexane ring.…”