Effect of Static Electricity in Textile Process

#Static Electricity:

If two surfaces some in close contact with each other and charge is created due to friction between them, the produced change remains enclosed and static in those surfaces. They will not move from one place to another. Here on by charges are exchanged between the two surface, this type of electricity is  called “state electricity” For example due to friction between glass rod and silk glass rod glass rod gains positive and silk gains negative charger.

This is static electricity, as this type of electricity is produced due to friction, (it is also known as frictional electricity. 

For explaining various circumstances regarding electricity various theories have been given in various time till now the following 5 theories are available: 

1.    Two-fluid theory

2.    One-Fluid theory

3.    Faraday’s theory

4.    Lorentz’s theory

5.    Modern theory

1.    Two fluid theory:

According to this theory in condition, a maternal has two fluids of opposite charges. Due to friction, one type of fluid flows form one maternal to another this the increment or decrement of another Thus The increment or decrement of charge our in two bodies Thus electricity produces.

2.    One-Fluid Theory:

This theory was postulated by Wattson and Franklin. According to this theory condition, everybody has a definite quantity of indestructible charge fluids. If there is an increment of this fluid the body gets positive charge and due to decrement of this fluid body gets negative charge.

3.    Faraday’s theory:

According to this theory if the charges produced by static electrical experimental are moved by electrical cell. We will get current electric.

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.

5.    Modern theory:

Now a- days the above 4 theories are discarded and the modern electron theoryis accepted. According to this theory every atom has a positively changed nucleus (positive charge is due to proton) and negatively charged electrons and protons are equal in neutral condition. If the no of electrons increases the atom because negatively charged and if the no. of electrons decreases the atom becomes negatively charged. 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 charged material in the cylinder induces an equal opposite charge on the inside of the cylinder. Again, outside the cylinder there produces equal charges of some sign This outside charge induces in the condenser. The potential (v) is measure by a valve voltmeter and if one knows the capacity (C) of the whole system the charge can be calculated by the following formula.

Q=CV

Where, Q= amount of charge induced in condenser.

V= Potential differences shown by voltmeter

C= Known Capacity of the whole system. 

#Problems Created due to state Electricity:

Static charge causes various problems in textile material and in processing some of them are illustrated below:

1. 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 if comes off a finishing machine and so on. 

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

3.  Again this charge attracts soil dust and dirt, so firmly that it Become difficult to remove them, when this occurs in loom it creates ‘Fog marking’. 

4. Charged bodies are attracted by an charged bodies Due to this charged fibres will stick to earthed parts of the machine happens particularly in carding.

5. When high enough field occurs, discharge in air will take place accompanying, sparks, There is also a risk of fire or explosion due in sparks. Again sparks form clothing are a source of danger where inflammable vapors are present as in operation theaters in hospitals.

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

7. Due to static charge the projection fibres remain stickled with the fabric. So they con not be removed by singeing and cropping. So dying and finishing become faulty. 

8. While passing over guides, due to state charge, roving experiences more friction and thus breakage may occur. Again due to allocation or repulsion roving can not be wound on to bobbin. easing.

#Method of Minimizing Static Problems:

As static charges causes various problems, they should be minimized by  the following ways:

1) By processing Aid:
By using conducting liquids like emulsion, oil friction between materials can be reduced. Thus formation static charge will be minimized.

2) By Moisturing:
By in creasing humidity of almost Pierre the resistance of material can be reduced So the charge will move and static charge will be minimized.

3) By using radio active material:
Radio-active material ionizes air which reduces static charge formation.

4) Antistatic Agent/By Finishing Treatment:
In man-made fibre spinning, by using anti-static agent with spin finish applicator the formation of static charge can be reduced.

4) By earthling:
By earthling the metallic M/C parts static charge can be neutralized. 

5) By Using Conductive Fibres:
By blending conductive fibres with non-conductive one, static problem can be minimized by discharge effect.

#Various hypothesis of charge transfer: 

There are various hypothesis regarding Charge Transfer and formation of static charge by that Generally it is thought that if the electrical condition of two bodies is not well balanced then a number of charge is exchanged when they care in contact with each other But this theory does not hold good for a good insulator which has not sufficient free electrons or ions here the various mechanisms of charge transfer are discussed

1. Potential difference:

If two metals in contact with each other which have potential difference, charge transfer will occur. These occurs due to energy level difference between them. This is shown in fig below in between two metals A and B.

 

When A and B will come in contact, electron flow will be happening until their energy will become same.



2.    Nature of charge & their distribution:

If charged particles are present on one or both of the surfaces, in contact, they will distribute themselves in equilibrium concentrations on each surfaces according to their relative affinity for each type of particle. This is important for the polymers containing ionic end group. Acetic polymers want to be negatively charge by leaving positive ions and basic polymers want to be positively charged by leaving negative charges. Thus charge transfer happens.


3.   Asymmetric rubbing:

Asymmetric rubbing will cause an unequal heating of the two surfaces and gives a thermal gradient across the interface. Mobile particles of any nature would then move from hot to cold owing to greater energy in hot particles.

4.    Double layer:

If there is a double layer on the surface of one body, or a layer of potentially ionizable groups, friction between two surfaces may cause a charged layer to be skimmed off then one surface onto the other.

5.   Piezo-electric polarization:

Piezo-electric polarization due to the pressure between two surfaces may result in a charge separation in crystalline or molecularly oriented surface. This is who shown by Martin in case of wool. 

Posted By:

Md. Zamil Mia

Campus Correspondent

Shyamoli Textile Engineering College