acetic acid have detrimental action on cotton
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The effects of chemical pre-treatments using dilute acids [HCl, CH3COOH, HCOOH, (CH2COOH)2C(OH)COOH] and alkali (NaOH) on raw jute and jute-cotton(75:25) union fabric and the effects of specified mixed enzyme system (different proportion of mixture of cellulase, xylanase and pectinase) pretreatment on conventional 2% H2O2 bleached jute-cotton union fabric have been comparatively evaluated. Among different organic/ mineral acid pretreatments 1% HCl treatment shows higher surface brightening action than that obtained by formic acid, acetic acid and citric acid pre-treatment. All these acid pretreatment do not show desirable softening action but show varying degree of surface leaching action associated with measurable changes in K/S value, whiteness, yellowness and brightness indices. However, 10-18% NaOH pretreatment of raw jute-cotton union fabric show appreciable softening action but is associated with higher mass loss, appreciable reduction in tenacity and surface darkening. While, 5% dilute NaOH pretreatment show somewhat less softening action, but exhibit lower mass loss, lower surface darkening and lower reduction in tenacity which may be practically useful in imparting desirable softness in jute-cotton union fabric. Treatment with specified cellulase enriched mixed enzyme system (175unit/ml of cellulase, 96 unit/ml of xylanase and 136unit/ml of pectinase) on either 1 or 5% NaOH pretreated or conventional 2% H2O2 bleached jute-cotton union fabric renders a moderate degree of softening action and surface smoothening with overall good balance in important textile related properties. However, higher degree of softening action may be achieved, if the said mixed enzyme treatment is carried out after both sequential pretreatments i.e. 5% NaOH pretreatment followed by conventional H2O2 bleaching at the cost of higher weight loss and reduction in tenacity. Studies on Dyeability of such chemically treated jute-cotton union fabric reveals that NaOH pretreatment show an increasing trend for acid dye uptake and reactive dye uptake, while all the dilute acid pretreatments show an increasing trend of basic dye uptake in general.
Keywords: acid pretreatment, alkali pretreatment, dyeability, H2O2 bleaching, mixed enzyme treatment, jute-cotton union fabric, softening; abrasion resistance, jute fibre, upholstery, neutralization, non-ionic detergent, humidity, initial modulus, breaking extension, bending length, sasmira stiffness tester