M. Okada, T. Hayakawa
Mar 15, 1993
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Journal
Journal of Polymer Science Part A
Abstract
A novel polyamide containing trans-2,5-linked tetrahydropyran rings in the main chain, poly(trans-tetrahydropyran-2,5-diyliminocarbonyl) (trans-polyamide 6), was synthesized by the two-stage polycondensation of ethyl or 2,2,2-trifluoroethyl trans-5-aminotetrahydropyran-2-carboxylate (5b or 5c). The polycondensation was carried out first in m-cresol at 180°C. The isolated polymer of a relatively low molecular weight was then allowed to react further in a solid state at different temperatures between 180 and 230°C under vacuum. The trans-polyamide 6 thus obtained was soluble only in protic solvents such as m-cresol, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-isopropanol, and trifluoroacetic acid. The viscosity numbers of 6 were up to 0.46 dL/g in m-cresol at 25°C. DSC and TGA analyses of 6 showed that the thermal decomposition occurred at about 350°C in nitrogen, whereas a rapid weight decrease due to the thermooxidative decomposition started at about 300°C in air. The moisture sorption isotherm was determined on coarsely ground samples of 6 at 25°C and compared with those for the structurally-related polyamides 2 and 4. © 1993 John Wiley & Sons, Inc.