Under the following conditions mono azo disperse dyes were applied to polyester:
The dyeing bath was settled at 40- 60ºC by adding the calculated volumes of dispersing agent ( Ejanal , 1g /l ), acetic acid ( pH= 5 - 5.5 ), dye ( 2% ) and water, where liquor ratio was kept at 1:30 . Fabric sample (polyester or polyamide) was added to the bath and temperature was raised gradually to 130ºC for polyester, through 15 minutes). Dyeing was continued at 130º C for 60 minutes then the dyeing bath gradually cooled .On completion of dyeing, the fabric was taken out and washed in a solution containing 5 g/l detergent at 60°C for 15 min. Finally, the washed fabric sample was rinsed with water and dried at ambient conditions.
the value of K/S of the disperse dyes decrease by change of H in benzene ring by substituent likes CH3 ,OCH3 , Cl, NO2 ……but it should increase.
Dear Sir,
prior to answer, I need some infos about the positions of your substituents (siehe your question) . On other part, polyester or polyamide are POLYMERS and a motion occurs during the staining at your temperature and the diffusion of dye depends mostly from the vibration- and rotation motions in your bath. (see and read the chapter of J.Crank and G.S. park in : Diffusion in Polymers Academic Press London 1968 and ref. cited and H.L. Frisch J.Chem. Physics 41, 3679 (1964).
Good luck
JRG
Dear Jean Rene Grezes
The position of substituent in benzene ring as following:
Ar=Ph, Ar=4-MeC6H4, Ar=4-MeOC6H4, Ar =2-ClC6H4, Ar=4-NO2C6H4, Ar=2-MeC6H4, Ar=3-MeC6H4, Ar=2-MeOC6H4, Ar=3-ClC6H4
Dear Sir,
thank you very much for your fast answer. Comments in due course.
However the different positions of the substituents will complicate the comparison(steric hindrance a.s.o...) . Please see the 3 D structure of your azo dyes on computer.
Have you the possibility to read the book of P. Rys and H. Zollinger :Dye chemistry Verlag Chemie 1982, page 186 .....
Another question: are you using during your investigation the Kubelka-Munk equation as follows:
K/S = (1-R)2 (2 as exponent) /2R
with K coeff. of absortion, S coeff. of scattering, R the refectance value of the fabric at the peak wavelength.
Thank you in advance for your answer.
Good luck
JRG
Do you mean the sum of k/s values or the k/s value at maximum wavelength. The maximum absorption wavelength of disperse dyes increases by change of H in benzene ring by substituent likes CH3 ,OCH3 , Cl, NO2 etc. According to this equation:K/S = (1-R)2 (2 as exponent) /2R, it can not guarantee the K/S values would be increased as well.
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