B. Vanhaecht et al., Controlled stereochemistry of polyamides derived from cis/trans-1,4-cyclohexanedicarboxylic acid, J POL SC PC, 39(6), 2001, pp. 833-840
Citations number
14
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
A series of copolyamides 12.y was synthesized either with y = 6, or 1,4-cyc
lohexanedicarboxylic acid (1,4-CHDA) residue, or a mixture of both. The inf
luence of the synthetic route of 1,4-CHDA containing polyamides on the obta
ined cis-trans ratio of the incorporated 1,4-CHDA was investigated. The use
of acid chlorides provided a synthetic route with full control of the cis-
trans ratio of the 1,4-CHDA residue during synthesis, whereas synthesis at
elevated pressure and temperature caused isomerization. The content and cis
-trans ratio of 1,4-CHDA in the copolyamides were determined by solution C-
13 NMR spectroscopy. Increasing the degree of partial substitution of the a
dipic acid by 1,4-CHDA resulted in an increase in T-m, even for low molar p
recentages of 1,4-CHDA. This phenomenon points to isomorphous crystallizati
on of both the 12.6 and 12.CHDA repeating units. The mps of the synthesized
polyamides were independent of the initial cis-trans ratio of 1,4-CHDA, pr
ovided that the samples were annealed at 300 degreesC before DSC analysis.
The polyamides exhibited a different melting pattern depending on the 1,4-C
HDA content. At a low a 1,4-CHDA content a net exothermic recrystallization
occurred during melting, whereas at higher contents of 1,4-CHDA this recry
stallization occurs to a lesser extent, and two separate melting areas are
observed. (C) 2001 John Wiley & Sons, Inc.