Effect of Stoichiometric Imbalances on the Melt Condensation Polymerization of Poly(dodecamethylene terephthalamide) Studied by Intrinsic Viscosity and 13C-NMR

Lon J. Mathias, University of Southern Mississippi

Originally published in Journal of Applied Polymer Science, Volume 116, Issue 6, 15 June 2010, Pages 3388-3395

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Abstract

Poly(dodecamethylene terephthalamide) (PA-12,T) was synthesized by melt condensation polymerization of 12,T salt with 0, 1, 3, 5, or 10% molar excess of 1,12-diaminododecane (DA), terephthalic acid (TA), or benzoic acid (BA). Intrinsic viscosities (IV) (0.5 g/dL in 96% H2SO4 at 25̃C) were measured to determine relative molecular weight differences. IV was highest for reactions containing 1 and 3 mol % excess DA (1.36 and 1.31 dL/g, respectively), followed by the product of pure 1 : 1 salt (1.25 dL/g). For all concentrations of excess TA and BA, IV was decreased. 13CNMR chemical shifts for DA, TA, and BA end groups were identified and their concentrations determined by comparison with the intensity of main chain polymer peaks. A log-log plot of IV versus number average molecular weight calculated from 13C-NMR data shows a linear trend with Mark-Houwink constants of K = 55.8- 105 dL/g and α = 0.81. VC 2010 Wiley Periodicals, Inc