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Determination of the amino end groups in polyamide 6 and 6,6 with ninhydrin

1980; Wiley; Volume: 86; Issue: 1 Linguagem: Inglês

10.1002/apmc.1980.050860115

1522-9505

J. F. Knott, Volker Rossbach,

Microbial bioremediation and biosurfactants

Abstract The amino end groups in polyamide 6 and 6,6 were reacted in a water/methylcellosolve/propionic acid/sodium propionate/pyridine/isopropanol system for 30 min at 100°C with ninhydrin to give a dye (λ max : 570 nm, ϵ 570 : 18.6 · 10 3 cm 2 mol −1 ), whose photometrically determinable concentration represented a measure of the amino end group content. Although the polymer remained undissolved during the analysis, the reaction proceeded quantitatively in all the samples studied (fibres with a maximum fineness of 44 dtex, corresponding to a diameter of 70 μm). ϵ‐Aminocaproic acid served as a low‐molecular calibration substance for the polymer. On account of its simplicity, rapidity, and good reproducibility (variation coefficient 3.4%), the ninhydrin method is suitable for the serial determination of the amino end groups in polyamide 6 and 6,6.