EQUILIBRIUM CHEMICAL CHARACTERISTICS OF NYLON-ACRYLIC ACID GRAFT COPOLYMER
Technical rept. Jan 1965-Jul 1968
ARMY NATICK LABS MA CLOTHING AND PERSONAL LIFE SUPPORT EQUIPMENT LAB
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The radiation-grafted polymer of acrylic acid on nylon 6,6 - a fiber with flash- resistant properties, was studied as representative of a new and useful class of textile fibers. The present report covers the first phase of research on the fundamental chemical properties of this fiber. Equilibriumcharacteristics are discussed and results of work on kinetics will follow. Equilibrium studies were made of rapidly-stirred suspensions of finely cut polymer fiber at several temperatures 30 -60C. The base-reactive capacitypotassium hydroxide was 2.0 milliequivalents per gram at 30C about twenty times that of the base polymer, with no significant change in capacity at higher temperatures. The acid strength of the copolymer was unexpectedlylow apparent pKa9, an effect attributed to a heightened polyelectrolyte effect caused by restricted mobility of the carboxyl groups. Evidence for a conformational transition of the polymer chain at about 55 ionization was shown by a discontinuity in the Henderson- Hasselbach plot of the titration curve. This was attributed to a reversible shifting of the polymer chains. Neutralelectrolyte caused a distinct increase in the apparent acid strength pKa - 5.8,and a delay in the transition to a point later in the titration 95 neutralized.No effect of temperature on the equilibrium characteristics of the copolymer was observed.
- Polymer Chemistry