Textile Physics-II (FR)

Static Electricity

Static electricity: If two surfaces come in close contact with each other, charge is created in them
due to friction. The produced charges remain enclosed and static in their surfaces. They cannot
move from one place to another, here only charges are exchanged between the two surfaces. This
type of electricity is called static electricity. For instance, friction between the silk fabric and
glass rod; positive charge is created on the glass rod and negative charge on the silk which
remain stationary and cannot move. As this type of electricity is produced due to friction so they
also called frictional electricity.
Theories of static electricity: For explaining various circumstance regarding electricity various
theories have been given in various time. Now the following five theories are available,
1. Two fluid theory: According to this theory in uncharged or neutral condition a material has
two of opposite charges. Due to friction, one type of fluid flows from one material to another.
Thus, an increment or decrement of the charge occurs in the bodies. Thus, electricity produced.
2. One fluid theory: This theory was postulated by Watt and Franklin. According to this theory
in uncharged or neutral condition of a material, it has a definite quantity of indestructible charge
fluid. If there is an increment of this charge, then the body gets positive charged and vice-versa.
3. Faraday’s theory: According to this theory, if the charges produced by static electrical
experiment are moved by electric cell, we will get current electricity.
4. Lorentz theory: According to this theory positive and negative charges are not two different
types of fluid, rather they are two oppositely charged particles.

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5. Modern theory: Now-a-days the above 4 theories are discarded and the modern electron
theory is accepted.
“Static electricity is simply an imbalance in the distribution of electrons. May be defined as an
accumulation of the time in variant charge of positive (+ve) or negative (-ve) sign on a material
either locally or fully. This charge often generates a high voltage associated with low current
levels.”
According to this theory every atom has a positively charged stationary nucleus due to the
presence of positive charged particles called protons and negatively charged electrons moving
round the nucleus. In neutral or uncharged condition, the no. of rotating electrons is equal to the
no. of proton present in the nucleus. If the no. of electrons increases the atom becomes
negatively charged and if the no. of electrons decreases the atom becomes positively charged.
Measurement of magnitude of charge: The amount of static charge present should be expressed
by the magnitude of charge on the material. This may be measured by using Faraday’s cylinder.
The following figure shows the apparatus used by Keggin to measure the charge on card sliver.

The charge material in the cylinder induces an equal and opposite charges on the inside of the
cylinder. Again, outside the cylinder, there produces equal charge of same sign of the material
inside cylinder. This outside charge induces in the condenser. The potential difference ‘V’ is
measured by a value voltmeter and if one knows the total capacitance of the whole system, then
the charge can be calculated by the following formula,
Q = CV
Where, Q = Amount of charge induced in cylinder
C = Known capacitance of the whole system
V = Potential difference shown by voltmeter

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Textile Physics-II (FR)

Problems due to static electricity in Textile sector:

 Similar charges repel one another. This causes difficulty in handling materials for instance
filaments in a charged ware will repel one another, there will be ballooning of a bundle of
slivers, cloth will not fold down neatly upon itself when it comes off a finishing machine
and so on.

 Opposite charges attract one another. This causes difficulty in the opening of parachute.
This will also cause tow garment to stick to each other.

 Again this charge attracts soil dust and dirt, so firmly that it becomes difficult to remove
them.

 Charged bodies are attracted by other charged bodies. For this reason, charged fibers will
stick to earthed parts of the machine. It happens particularly in carding.

 When high enough field occurs, discharge in air will take place accompanying, sparks,
There is also a risk of fire or explosion due to sparks.

 Large amount of accumulated static charge may give shock to people especially where a
large insulated conductor becomes charged up.

 Due to static charge the projecting fibers remain stuck with the fabric. So they cannot be
removed by singeing and cropping. So dyeing and finishing become faulty.

 While passing over guides, due to static charge, roving experiences more friction and thus
breakage may occur. Again due to allocation or repulsion, roving cannot be wound on to
bobbin easily.
Method of minimizing static problem:
As static electricity causes various problems they should be minimized by the following
ways:-

 By processing aids: By using conducting liquids like emulsion, oil, etc. friction between
the materials can be minimized/reduced. Thus, formation of static electricity can be
minimized.
 By changing relative humidity: By increasing humidity of atmosphere, the resistance of
the materials can be reduced so that the static charge will move and static problems will be
minimized. This can also be done by spraying water.
 By using radioactive material: Radioactive materials ionize the air which reduces the
static charge formation.
 By finishing treatment: In man-made fiber spinning by using antistatic agent with spin
finish applicator the formation of static charge can be reduced.
 By earthing: By earthing the metallic machine components of static charge can be
neutralized.

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 By using conductive fibers: By blending conductive fibers with non- conductive ones
static problem may be minimized by the discharge effect.

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