engleski

QUANTITY DETERMINATION OF AVAILABLE FREE HYDROXYL GROUPS IN PRETREATED COTTON

Differently pretreated knitted cotton fabrics, including raw, untreated cotton sample, were dyed. Pretreatment processes included alkaline scouring, prebleaching, enzymatic treatment and mercerization, while monofunctional, reactive dye C.I. Reactive Blue 19, which establishes covalent chemical bonds with hydroxyl groups of cotton through a mechanism of nucleophilic addition, was used in dyeing. Quantity of exhausted and covalently bonded dye was determined spectrophotometrically. Cotton pretreatment processes were proven to influence no effect on availability of hydroxyl groups in cotton, except for mercerized samples in which the number of available groups was increased by significant 30%. However, pretreatment processes play a key role in the period of first 30 minutes of dyeing process, time in which dye exhaustion occurs. Quantity of hydroxyl groups in cotton was calculated from the amount of covalently bonded monofunctional dye.

pretreatment; enzymatic treatment; mercerization; reactive dyeing; hydroxyl group; covalent bond

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