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