الفهرس 
Light fadingOnly 14 pages are availabe for public view
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Abstract
The origenal :,;ark presented i n t h i s t h e s i s was undertaken to verify the f o l l o w i n g p o i n t s : 1, Sffect of pretreatrnents usuzlly used on cotton f a b r i c s on tbe behavioln of the latter towards dyeing with r e a c t i v e dyes, 2. Sffect of -:~hesep retreatinents on the s u s c e p t i b i l i t y o f t h e dyed fabyica to l i g h t f a d i n g , 3. E f f e c t of t h e p~etreatmentst o which polyester/cotton b l s n d e d f a b r i c s a r e u s u a l l y subjected on the d y e a b i l i t y of the f a b r i c s with a disperse/reactive dye system. 40 To what e x t e n t does t h e s e pretreatrnents i n f l u e n c e the lightf a s t n e s s of the dyed blend. Presented below a r e the summary t o g e t h e r with the cot?c?tls i o n s a r r i v e d at from these s t u d i e s . I, E f f e c t of Pretreatments on Dyeing of Cotton w i t h R e a c t i v e Dyes, --I------------ -- -Q e-.a--b--i- li.---t..y. : Cotton fabric wa.5 subjected t o a number of pretreatrnents viz . de sizing: .scouring; half bleaching, full bleaching and. mercerizing, The faSrics were dyed before and a f t e r these pretreatments with s i x f i b r e r e a c t i v e dyes, O f these dyes thrse are basad on cyanuryl halide g~oupsv lz, Cibacron B r i l l i a n t Red 2G---I?, Cibacron Brilliant Blue E7BR-P and Cibacron Yellow R-A. Whereas the other three dyes are based on sulpha-to-- ethyl groups viz, Remazol B r i l l i a n t Red 5B, Remazol Blue 3R, and Remazol B r i l l i a n t Yellow 7GLo The dyed f a b r i c s were %hen analyzed f o r the colour s t r e n g t h (dye f i x a t i o n ) t o see in p a r t i c u l a r the e f f e c t of such pretreatmen-5s on the dyeabili-tg of t h e c o t t o n fabr5.c~. Conclusion a r r i v e d a t from these s t u d i e s may be drawn as follot~s: 1, Regardless of the pretreatment, the colour s t r e n g t h i n c r e a s e s with i n c r e a s i n g t h e dye concentration up t o the maximum ccncentrai-ion used i n t h i s ’study, (40 g/l) i n case of Cibacron dyes and up t o 20 g/l in case of Remazol dyes, 2 , The pretreatrnents have a s i g n i f i c a n t favourable e f f e c t on d y e a b i l i t y of the f a b r i c . The colour strength follows the following orde~: Mercerized cotton) f u l l bleached cotton half bleached - ,/’ > cotton} scoured cot ton > desized g r e y c o t t o n . 3, The enhancement in colour s t r e n g t h r e l i e s on the nature of the dye used, That is the enhancenent in d y e a b i l i t y brought about by the pretreatment dey?ends on substituents, s t e r i c cor?.fi.gurati.~ra nd d i f f u s i b i l i t y of t h e dye, 4, Wi-thin the range studied, some dyes benifit much more than -;he others as a r e s u l t of the pretreatments in question. Zence it was postulated that it is n o t t h e r e a c t i v i t y of the dye towards c e l l u l o s e which decides the magnitude of enhancement in colour strength but a l s o the r e a c t i v i t y of the dye towards impurities. Dyes with higher a f f i n i t y t o the l a t t e r would be expectzd to give higher colour strengtht on the f a b r i c , if these i m p u r i t i e s are removed p r i o r t o dyeing, Competition between the dye-impurities reaction and dyeceilulose ~eactionw ould n o t be no more t h e r e . React ion of the dye would be only confine t o c e l l u l o s e , 5, With very few conception, f u l l bleaching and/or mercerizing did not enhance the colour s t r e n g t h of the half bleached cotton f a b r i c , It is believed t h a t during desizing, scouring and half bleaching most, if not a l l , the i m p u r i t i e s i n the Tabric are removed. A s a r e s u l t the f a b r i c d y e a b i l i t y improved to a considerable extent. Subjecting the f a b r i c t o f u r t h e r bleaching and mercerizing may creat carbony1 and/ or carboxyl groups along t h e c e l l u l o s e chain molecules which impede reastion of the r e a c t i v e dye with cellulose., Short degrade cellulosas are a l s o l i k e l y i;o occur during t h e s e two processes, Removal of the sz degraded c e l l u l o s e s a f t e r dyeing lowers the colour s t r e n g t h , Both e f f e c t s seem 30 outweight the increase in colour strength expected from increased a c c e s s i b i l i t y by mercerizing.