SU1448368A1 - Device for polarization of polymer bodies - Google Patents

Description

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The invention relates to devices that allow to obtain the necessary degree of polarization of polymer bodies.

It is known a device used for polarization of slimming bodies in strong electric fields, the polarization intensity being realized is 0.6 MV / cm and too small for effective polarization at both high and low temperatures. This device contains a pulse voltage source, a voltage meter and a temperature control unit. Oh.

A disadvantage of the known device is the low polarization efficiency of polymer bodies due to the use of complex technical means, as well as the lack of control and management of the polarization process.

The aim of the invention is to increase the polarization efficiency of the polymer bodies by controlling and controlling the course of the polarization process by incorporating a charge into the circuit of an additional capacitor whose capacity exceeds the capacitance between the plates of the unpolarized polymeric body.

The polarization process employs a high-voltage auxiliary capacitor connected in series to the charge circuit.

The capacitance C2 of the additional capacitor is chosen so that (at least one order of magnitude), where C denotes the capacity of the polymer body metallized on both sides, B of such conditions at the beginning of the polarization process is almost complete polarization voltage Ufj, initial the value of which should correspond to a voltage of not less than 4000 kV cm, falls on the polymer body and causes the orientation of the polar groups of molecules in the polymer body in the direction of the applied electric field. During polarization, the optimal choice of the capacitance Cg of the series capacitor redistributes the polarization voltage Up from the polymer body to the series capacitor, so that even with extremely large values for Up there can be no

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crystal sample in the polymer body. Polarization is preferably carried out at temperatures Tp, for which

2 Tr - T ((1 - melting point

of this polymer body), while Up remains applied until the polymer body is cooled to room temperature or cooled to 20 below Tp by cooling. The duration of the polarization process is 10-300 seconds. A cybernetic interaction occurs between the additional capacitor and the polymer body. The faster the polarization increases in the polymer body, the shorter is the time when the total voltage Up is applied to the polymer body. When the degree of polarization has reached its maximum value, the redistribution of voltage across the series capacitor is complete, and a voltage is applied to the polymer body at which there can be no electrical breakdown. Therefore, it is possible even at temperatures Tp, when electric breakdowns have always occurred at the application of relatively high voltages, to polarize with high field strengths, do not expect electrical breakdowns due to the short duration of the current voltage pulse. In addition, an additional capacitor has a current-limiting effect if a breakdown in the polymer body occurs in the polarization process.

Example 1. Polarization of fluoropolymers. With tsenstvuyu advantages. In modification 1, a monoaxially oriented polyvinylidene fluoride film with a thickness of 0.010 mm is metallized on both sides by spraying aluminum (1.0 cm round area) and is heated to a polarization temperature of. The additional capacitor used in the polarization has a capacity of 10 nf, which exceeds by more than one order the capacity of the untreated polymer film. After switching on the polarization voltage of 5 kV, the voltage U on the additional capacitor increases by more than 2.5 kV for one minute, so that in the far process of polarization the voltage applied to the sample is less than 2.5 kV. At the beginning of the polarization almost

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full polarization voltage is applied to the sample and causes dipole orientation. After five minutes of polarization, the sample is cooled to room temperature, while maintaining the intensity of the field. As a result of this process of polarization, the polyvinyldene fluoride film receives a piezoelectric coefficient of 8 x 10 units. CGSE and pyroelectric coefficient of 8 nK / sm.K.

When polarizing a biaxially oriented polyvinylidefluoride film (metallized area of 0.8cM with a thickness of 0.006 mm, a polarization voltage of 2.5 kV is applied at using the same additional capacitor. Polarization can be carried out without electrical breakdown (piezoelectric coefficient of 5-10 units). CGSE, pyroelectric coefficient 4 nK / cm -K)

Polarization of polyfins; 1k films of 0.015 mm thickness (1 cm methactimised area) requires a series capacitor with a capacity of 1 nF. The polarization temperature is, and the polarization voltage is 6 kV. As a result of the polarization, in this case, a pyroelectric coefficient of 2 nK / cm -K was obtained,

Example 2 Polymerization of polyacryl nitrile:

The polarization of polyacrylonitrile is based on highly oriented films (uniaxially oriented) with a thickness of 0.010 mm (metallized area of 1 cm). The capacitance of the series capacitor in this case is 5 nF, the polarization voltage is 5 kV. Polarization is carried out at 120 s according to the described mode. The resulting pyroelectric coefficient is 4 nK / cm-K.

Froze Polyamide polyamides. A gialymould-based, uniaxially oriented polyamide film with a thickness of 0.010 mm is metallized on both sides with aluminum (the metallized area is 1 cm). The polarization temperature is 120 s; a polarization is applied.

voltage 5 kV. The capacitance of the series capacitor is 5 nf. The film is polarized for 5 minutes and then cooled in an electric field to room temperature.

Under the same conditions of polarization, films obtained from a 2% solution in formic acid (0.010 mm thick) based on polyamide - 7 and polyamide - 55 were also polarized.

Before polarization, the films were subjected to a 4-fold stretch and then metallized with aluminum (0.8 cm area).

The pyroelectric coefficients are 2 nK / cm "K for polyamide 11 and 3 nK / cm K for polyamides - 55 and -7.

The proposed device can carry out polarization with extremely high voltages without breakdowns.

fields. Polarized polymer bodies differ in piezoelectric and / or pyroelectric coefficients, whose values are above average. The device is implemented by simple means. The duration of polarization is in the range from several seconds to several minutes. The proposed device can be effectively used mainly in the polarization of polymeric materials.

bodies in the form of a film or foil having polar groups in the primary structure of molecules. As such polymers, halogenated vinyl polymers, polyesters and polyamides, polyurethanes, polymexanes can be used. Cheviny, polyacrylonitrile and polycarbonates.

Claims (1)

A DEVICE FOR POLARIZING POLYMER BODIES, containing a pulse voltage source with terminals for connecting to metallized plates of a polymer body and a polymer temperature control unit, characterized in that a capacitor is additionally included in the charge circuit, the capacitance of which exceeds the capacity between the plates of an unpolarized polymer body. QO QO α »oo