Chemical Analysis of Synthetic Fibers

Abstract

Dedicated to Professor Paul Schlack on the occasion of his 75th birthdayThe analytical characterization of synthetic fibers has not kept pace with their development and production. Whereas the "second-generation" fibers have already conquered the market, the chemical investigation methods used until now for the three classical fiber polymers of the polyester, polyamide, and polyacrylonitrile types are still frequently unsatisfactory. Though they satisfy the requirements of production supervision and quality control, they do not supply enough information to enable us to understand and to explain the degradation of and damage to the polymers under hydrolytic, thermal, or thermooxidative influences. This report presents methods of chemical analysis that open up new possibilities for investigations of this nature on synthetic fibers. The results reported for commercial products must not be taken as an assessment of quality. They are simply intended to show the diversity to be expected in the chemical properties and to emphasize the practical basis of the chemical analysis of synthetic fibers.

Modeling Equilibrium Behavior of Nylon 6, Nylon 6,6 and Nylon 6/6,6 Copolymer

“…The corresponding equilibrium water and amide link concentrations are then calculated from measured end‐group concentrations using mass balances . Titration experiments to determine [ A ] actually measure the concentration of all basic end groups on the polymer chains, so that any amidine ends that might be present are counted as if they are amine ends . Similarly, titrations to determine [ C ] actually measure the concentrations of all acidic end groups so that ends of type S (sometimes present in nylon 6,6) and C* are counted as if they were regular carboxyl ends.…”

A Kinetic Model for Non‐Oxidative Thermal Degradation of Nylon 66

“…However, since the Schiff base species SB1 and the secondary amine species A2 are basic groups that may also react with acid, we assume that [A] meas , the value of the amine end‐group concentration determined by titration, is actually the sum [A] + [SB1] + [A2] + [P244]. This assumption is supported by the work of Reimschuessel and Dege,35 Nissen et al,36 and Curran and Siggia 37. We assume that species SB2 and SB3 that appear along polymer chains, rather than at the ends, do not influence the titration results, so [SB2] and [SB3] are not included in the expression for [A] meas .…”