Why can plastics generate static electricity even though they are not conductors?

Plastics are all polymer materials, and the surface resistance and volume resistance are greater than 10 to the 12th power. Thus, the plastic material is endowed with good insulating properties. And it is for this reason that he is very prone to static electricity, because plastics and their products are very possible, or even impossible to avoid, in the production, handling, contact, separation, friction, collision, and intervention of electromagnetic induction occasions.

Factors for the generation of static electricity in plastics:

Microscopic causes: According to the theory of atomic physics, matter is in electric equilibrium when it is electrically neutral. Due to the contact of atoms of different substances, the electrons are gained and lost, so that the matter loses its electrical equilibrium and produces the phenomenon of electrostatics.

Macroscopic causes: friction between objects generates heat, which stimulates electron transfer; Contact and separation between objects produce electron transfer; Electromagnetic induction causes an unbalanced distribution of charges on the surface of objects; The combined effects of friction and electromagnetic induction.

It is precisely because plastic is not a conductor that static electricity can be generated. Friction, contact and separation between objects, electromagnetic induction causes an unbalanced distribution of charges on the surface of objects, thus generating static electricity. Some materials are electrically conductive.

Well, there will be no static accumulation. Plastics have poor electrical conductivity, and the static electricity generated cannot flow, resulting in the accumulation of static electricity.

The first thing to do is to generate static electricity is a false idea, and the phenomenon of static electricity is essentially the transfer of electrons. The transfer of electrons is due to the difference in the ability of the two objects to bind electrons, the weaker ability to bind electrons will lose electrons, and the electrons will be transferred to the objects with strong binding ability. For example, if the fur and the rubber rod rub, the rubber rod is not a conductor, but the rubber rod will be negatively charged with electrons, and the fur will lose electrons and be positively charged!

Plastic does not fall to the bottom but can generate static electricity, because plastic has extremely strong friction.

Any two objects of different materials come into contact and then separate, static electricity can be generated, and the common method of generating static electricity is triboelectric electricity. The better the insulation of the material, the more likely it is to generate static electricity.

Static electricity is formed by the redistribution of charges caused by friction, and there are also forms of redistribution of charges due to the mutual attraction of charges. In general, the positive charge of the nucleus is equal to the negative charge of the electron, and the positive and negative are balanced, so it is not electrically visible.

However, if the electrons are deorbited by an external force, resulting in an unbalanced electron distribution, for example, triboelectric is essentially a process that causes an imbalance of positive and negative charges. When two different objects touch each other and rub against each other, the electrons of one object are transferred to the other and become positively charged because of the lack of electrons, while the other body gets some remaining electrons and the object is negatively charged, and the object is electrostatic.

Electrostatic precipitator can be considered as an electrostatic conductor, and the principle of electrostatic precipitator is:

When a gas containing dust particles passes through a high-voltage electric field formed between a cathode wire (also known as a corona electrode) connected to a high-voltage DC power supply and an anode plate that is grounded, the cathode is discharged and the gas is ionized.

At this time, the negatively charged gas ions, under the action of the electric field force, move to the sunny plate, and collide with the dust particles in the movement, the dust particles are charged with negative electricity, and the charged dust particles are under the action of the electric field force, and the finch liquid also moves towards the anode, and after reaching the anode, the stuffy electrons are released, and the dust particles are deposited on the anode plate, and the purified gas is discharged out of the dust filter.

Necessary conditions for electrostatic equilibrium of conductors:

The electric field strength at each point inside the conductor is zero. If the strength of the electric field inside the conductor is not zero everywhere, the charge will move under the action of the electric field, which is not electrostatic equilibrium.

The characteristic of a conductor is that it has a free moving charge, and these free charges will move in a directional motion when they are stressed in an electric field, and "electrostatic equilibrium" refers to the state in which the force on the free charge in the conductor reaches equilibrium and no longer moves in a directional motion. The condition for a homogeneous conductor to reach electrostatic equilibrium is that the combined field strength inside the conductor is zero everywhere.

The above content reference: Encyclopedia - electrostatic conductor.

Static electricity everywhere Matter is made up of atoms, and there are uncharged neutrons, positively charged protons, and electrons with negative charges in the Hoohs belt. Under normal conditions, the protons and electrons in an atom are equal in number, and the positive and negative charges are balanced, so they exhibit an uncharged phenomenon. When two objects rub against each other, the heat generated increases the electron energy level, so that the inactive electrons become active electrons that are easy to escape, and such electrons can be transferred from one object to another, so that the two objects that are originally neutral become charged objects, which is the well-known "triboelectric generation" phenomenon of friendship.

In the process of triboelectric generation, the amount and speed of electron transfer are not only related to the properties of the material, but also to the temperature and humidity in the field. In autumn and winter, due to the low humidity of the air, the viscous force between the molecules is small, and the movement speed is accelerated, it is easy to generate static electricity. Not only does the moving air generate static electricity, but actions such as walking around the floor, rotating the swivel chair, opening and closing the drawer of the nuclear brigade, taking pen and paper, moving the mouse, etc., can also generate static electricity, which imparts an electrostatic charge to these objects and the human body.

In addition to triboelectric generation, there are also electrostatic causes such as "inductive electricity" and "capacitive electricity" in electrical equipment. Even if there is no contact between devices, circuits, and metal-to-non-metal structures, static electricity can be generated in both ways. As the saying goes, you don't shoot birds across mountains, but electrostatic induction between objects can occur even when they are separated by a distance

The CRT monitor screen, as an induction source, also induces static electricity on the body, covering our faces with dust; Parasitic capacitance is also transferred between two parallel wires.

The difference between anti-static plastics and conductive plastics is that anti-static plastics are actually non-conductive, while conductive plastics are electrically conductive.

Antistatic plastic is an ordinary plastic, plus antistatic agent, antistatic agent is a surfactant with poor compatibility with plastics.

It will slowly precipitate from the plastic to the plastic surface, the antistatic agent has a hydrophilic group, which can absorb a small amount of water, and the water is conductive, which can conduct the static electricity on the plastic surface, so as to avoid the human body being electrostatically charged. Conductive plastics are made of synthetic polymers with a special structure that can conduct electricity like metals, such as polypropylene, which is very popular now, and can conduct electricity like metals.

Physical elimination is employed.

It is the most commonly used method to eliminate the pre-cavity without changing the properties of the material and using the characteristics of the static electricity itself.

The generation of static electricity is as follows:

The object itself is generally considered to be electrically neutral, and when two materials with different chemical compositions or different physical states come into contact with each other, charge redistribution occurs on their respective surfaces. When two substances are reseparated, each material has an excess of positive or negative charge than before contact, and this form of charge is called static electricity.

Electrostatic phenomena are very common in the production, processing and use of polymer smart shirts. When plastic materials are rubbed, they are easy to carry static electricity, and the order of their charging is (positive) polyurethane, nylon, acetate, polypropylene, polyester, polyacrylonitrile, polyvinyl chloride, vinyl chloride-acrylonitrile copolymer, polyethylene, polytetrafluoroethylene (negative).

The magnitude of static electricity generated by a plastic can be expressed in terms of its surface resistivity or volume resistivity. Different types of plastic products tend to show different surface resistivity and volume resistivity. <>

Why electrostatic shielding.

The object inside the conductor is not electrified?

Electrostatic induction, electrostatic balance.

In addition, the physical background of the three phenomena is also the same, that is, they are all in the applied electric field (whether the electric field is uniform or not).

Electrostatic induction describes only the separation and redistribution of positive and negative charges in a conductor under the action of an applied electric field It runs through the whole process of the conductor from non-electrostatic equilibrium to electrostatic equilibrium Electrostatic equilibrium is the final phenomenon of electrostatic induction in conductors, electrostatic equilibrium focuses on describing the motion state of free charges in conductors, which should consider both the applied electric field and the electric field excited by the induced charge The discussion of electrostatic equilibrium is based on electrostatic induction, which is the most critical, The most basic point is that the internal combined field strength of the conductor is zero everywhere Electrostatic shielding focuses on the study and description of the interaction between the electric field inside and outside the conductor after the electrostatic equilibrium is reached Obviously, the electrostatic shielding phenomenon must be established on the basis of electrostatic equilibrium, and the essence of the phenomenon still involves electrostatic induction, because only by considering the external electric field and the additional electric field excited by the induced charge generated by the conductor due to electrostatic induction, can we deeply and completely understand the essence of the electrostatic shielding phenomenon

When the charge in a charged system (which can be a charged conductor) is stationary, so that the electric field distribution does not change with time, we say that the charged system has reached electrostatic equilibrium If we consider that the charge has to move thermally, then we can put it another way: the state in which there is no charge in the conductor (including the surface) to move is called the electrostatic equilibrium state of the conductor The characteristic of a conductor is that there are a large number of free electrons in its body.

They can move under the action of an electric field, which changes the charge distribution; In turn, the change of charge distribution will affect the electric field distribution (the reason why the charge line on the inductive conductor in the previous section is biased to the left end is to take this effect into account) It can be seen that when there is a conductor in the electric field, the charge distribution and the distribution of the electric field will affect and restrict each other, and not any distribution of charge and electric field is an electrostatic equilibrium distribution Must meet certain conditions before the conductor can achieve electrostatic equilibrium distribution

It is not that the object in the inner head is not charged, but that the object inside is not affected by the outside world, or that it is not disturbed by the outside world. For example, in cable television, the internal conductor still transmits cable TV signals. As for why the shield prevents external interference, it is the free electrons of the metal shield that disturb the energy from the outside world, which is not only absorbed by the free electrons that are missing, but also dedicates the absorbed energy to the earth without reservation, so that there is no external interference energy left to transmit to the inside of the shield, so that the inside of the shield can become an independent kingdom.

Friction produces static electricity, so how powerful is it?