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Electro-Kinetic properties of modified fibres , methods &
trends, Formula and explanation
ByDhanraj Desai (13TXT2017)
Electro-Kinetic properties of modified fibres
• Electro:- On the surface of fibre• Kinetic:- flowing of solution
3 Parameters have to study for Electro kinetic behavior of modified fibre.
Zeta Potential PropertySurface conductivitySurface charge density
Streaming potential Set-up
• Studying property Of modified fibreLike AA-g-PET,Aam-g-PET by Passing dye sol.Lower conc. 10mM-Higher conc.100mM
Zeta potential phenomenon• increased concentrationof counter ions (ions of opposite charge to that of the particle) close to theSurface.
• surface of hydrodynamic shear or slipping plane.
• The potential that exists at this boundary is known as the Zeta potential.
Zeta potential Value l)Zeta Potential Value =
6.75 x 10^7 (4 c . P= Zeta potential = Viscosity of solution (poise)X= Specific conductivity of sol. In the plug of the fibre /Ohm,/cm c= Dielectric constant of the solutionP= Pressure of the solution streaming through the cell, (cm of Hg) = Streaming potential (mV)
Zeta potential value of A.A-g-PET fibre vs N-PET
• Normal PET fibre has more -ve zeta potential value than g-PET.
• AA-g-PET fibre has more no. COO‾ group.
• So AA-g-PET is more hydrophilic than N-PET
• More cation dye absorb on surface of fibre and more neutralization of functional charge.
• Due to that overall –ve charge reduced
• Conc. of cation dye in streaming sol. is increases –ve zeta potential of N-PET, AA-g-PET goes reduce
• AA-g-PET reached up to isoelectric point but N-PET not.
Zeta potential value of A.Am-g-PET fibre vs N-PET• Dye Is anionic and fibre
is cationic in nature.
• If conc. of Acid dye increases the –ve zeta potential will increases due to depletion of dye on fibre surface.
Effect of pH on zeta potential value
• Isoelectric point in between pH 5-6pH
• As basicity increases –ve zeta potential increases and acidity increases +ve zeta potential increases
• Cotton -14• PET -36• PP -40
Zeta potential behavior of Amphoteric fibre
• Like amphoteric PET, wool, silk,etc.
• Sensitive to pH condition
Zeta potential value also depend on various factors
• pH of any fibres
• Surface area of fibre (Coarse shows less –ve zeta value)
• Heat set/Un heat set
• Modified/unmodified
• Swollen/un-swollen (swollen fibre is less zeta potential value)
Surface conductivity of fibre• It is difference of specific conductivity of streaming
solution(Ks) and of the plug (Kc)• Kf-surface conductivity of fibre• Kf=Ks-Kc
• Surface conductivi- ty of fibre at 7 pH is minimum
Surface charge density of fibre• Surface charge density
is less at 7 pH
Relation between surface conductivity and dye conc.
• As conc. of dye increases surface conductivity also increases
• Because by adding NaOH, Na+ ion and adding HCl to sol., H+ proton increases due to that conductivity increases.
Conclusion
• The differentially modified and unmodified PET fibres shows variation in interaction with different dye streaming solution resulting various electro kinetic property of fibres.
• Hydrophilic fibre shows less –ve zeta potential value
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