1. Electro-Kinetic properties of
modified fibres , methods &
trends, Formula and explanation
By
Dhanraj Desai (13TXT2017)

2. 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 Property
Surface conductivity
Surface charge density

3. Streaming potential Set-up
• Studying property
Of modified fibre
Like AA-g-PET,
Aam-g-PET by
Passing dye sol.
Lower conc. 10mM-
Higher
conc.100mM

4. Zeta potential phenomenon
• increased concentration
of counter ions (ions of opposite charge
to that of the particle) close to the
Surface.
• surface of hydrodynamic shear or
slipping plane.
• The potential that exists at this
boundary is known as the Zeta
potential.

5. Zeta potential Value
∆𝑉 𝑠𝑡𝑟𝑒𝑎𝑚𝑖𝑛𝑔(𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎l)
Zeta Potential Value =
∆𝑃 𝑠𝑡𝑟𝑒𝑎𝑚𝑖𝑛𝑔 (𝑝𝑟𝑒𝑠𝑢𝑢𝑟𝑒)
6.75 x 10^7 (4𝜋η ∗ ∆𝑉 𝑠𝑡𝑟𝑒𝑎𝑚. 𝑋)
ξ =
c . P
ξ= Zeta potential
η= Viscosity of solution (poise)
X= Specific conductivity of sol. In the plug of the fibre /Ohm,/cm
c= Dielectric constant of the solution
P= Pressure of the solution streaming through the cell, (cm of Hg)
∆𝑉 𝑠𝑡𝑟𝑒𝑎𝑚= Streaming potential (mV)

6. 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.

7. 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.

8. 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

9. Zeta potential behavior of
Amphoteric fibre
• Like amphoteric PET,
wool, silk,etc.
• Sensitive to pH
condition

10. 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)

11. 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

12. Surface charge density of fibre
• Surface charge density
is less at 7 pH

13. 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.

14. 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