The modification of the electrical properties of products of solid polymer dielectrics

 

(57) Abstract:

The invention is intended for the chemical industry and can be used in the manufacture of electroacoustic and Electromechanical transducers, gas filters, means for protection against static electricity. On the bottom glass flask was placed a powder or granules of iodine, 1,2-diamine-9,10-aminoanthraquinone, 1-hydroxy-9,10-anthraquinone. In the same flask, the product is a film, fiber, mesh, granules of the solid polymer dielectric, such as polymethylmethacrylate. The flask is closed, pumped up to 10-1- 10-2PA. The lower part of the flask is placed in a thermostat. Heated to a temperature of T = (1,3-1,6)Tg, where Tg is the glass transition temperature of the polymer. Upon reaching the impurity concentrations (3-5)10-3mol/l the product is cooled. The bulk conductivity of the modified polymer can be increased in 56-24000 times, reduced to 140 times the density of the surface charge is increased to 7-9 times or reduced 30 times, young's modulus, yield stress and strength are not changed. The invention also allows to neutralize the low molecular weight impurities in the polymer. 1 Il.

The invention relates to a method of processing polymeric materials (laid down is allenii using electrets electroacoustic and Electromechanical transducers, gas filters and also as a means of protection against electrostatic charges.

Known methods of modification of polymeric materials to increase their ability to polarization in various fields of technology, for example, to increase the sensitivity of electroacoustic transducers [1], the efficiency of filtration of fine particles in filters [2, ], performance (speed filtration) membranes [3], adhesion to the metal [4], changes in the optical properties of the product [5], reduce static electricity [6], carried out in various ways - by introducing into the solution or melt of polymer of low concentrations of impurities. Known also adopted for the prototype method volumetric modification of polymers and functional additives by processing pairs of modifying substance to impart new physical-chemical properties (optical, photo-, thermo-, radiation resistance, and others) [5].

The disadvantages of these methods is the possibility of introducing impurities in the polymer at the stage of raw materials or intermediate products, which negatively manifested on its physical-mechanical properties. The achievement of the desired concentration of additives proposed in [5] the method is carried out by argirov"ptx2">

The objective of the invention is the expansion of the use of different solid polymer dielectrics due to enable meaningful changes in the right direction electrophysical characteristics of solid polymer dielectrics (in the direction of increasing or decreasing values of electrical conductivity and the ability of the material to polarization) without changing other physico-mechanical properties.

The problem is solved in that the modification of the electrical properties of products of solid polymer dielectrics by introducing impurities in the polymer material, the introduction of impurities with donor or acceptor properties of a given polymer material is carried out of the gas phase, and before the introduction of impurities polymeric material is transferred to highly elastic to plastic state by heating it to a temperature

T = (1,3-1,6)Tg,

where T is the temperature of the polymer material,

Tgthe glass transition temperature of the polymer.

However, the introduction of impurities, it is advisable to carry out at a pressure of 10-1-10-2PA to the concentration of polymeric material (3-5)10-3mol/l, and the desired concentration of the FDS modification of the electrical properties of products of solid polymer dielectrics is as follows.

On the bottom glass flask (for laboratory samples. For industrial designs here and hereinafter the term "bulb" should be replaced by the term "vacuum chamber") is placed implement the admixture in the form of powder or granules. In the same flask on a special stand that there was no direct contact with the impurity, the product is placed in the form of a film or fabric, or fiber, or grid, or granules. The flask is closed with a glass lid with a hole for pumping air and is connected to the vacuum pump. The lower part of the flask containing the mixture and the product is placed in a thermostat (for laboratory samples. For industrial products is heated using a specially built into the camera heater and heated to a temperature T, which depends in this way on the glass transition temperature of the polymer, Tg:

T=1.3 To 1.6 Tg.

At this temperature the mixture is gradually transferred into the gas phase, and the product - highly elastic state. At the same time produce the pumping of air from the flask to a pressure of 10-1-10-2PA.

The product is maintained at the working temperature in the gas phase impurities during the time required to achieve a given concentration of impurities in the material. The exposure time is determined for each of the authorized temperature. Then pull the bulb from the chamber and cooling the product to room temperature, turn off the vacuum pump and let the vacuum chamber air, open the flask and get treated material together with stand. Then make the cleaning of the walls from the dye deposited on the upper cold part of the bulb as a result of condensation of vapors when handling product.

The change of the electrical properties of the material is confirmed by measurements before and after treatment values of volumetric static conductivity at intensity of 100 V/mm and a residual charge on the superficiality of termoelectrica obtained when the polarization of the polymer material in the form of a film in a field of 104In /mm at a temperature of 155oC for polymetylmetacrylate and 125oC for polyethylene terephthalate within 15 minutes

The concentration of impurities in the material after processing can be determined by the intensity of the characteristic bands in the spectra of optical absorption with regard to the extinction coefficient.

Industrial applicability of this method and getting verhaftet on the bulk conductivity and the density of the surface charge by the following examples (without change polymethylmethacrylate.

The heating temperature T=140oC

Processing time - 40 minutes

The concentration of iodine in the material - 510-3mol/L.

The bulk conductivity:

original sample - 1,710-15Ω-1m-1(an increase of 135 times)

- processed sample - 2,110-13Ω-1m-1(an increase of 135 times)

The density of the surface charge:

original sample - 5 NC/cm2(increase 9 times)

- processed sample - 44 NC/cm2(increase 9 times)

Example 2.

Introduction 1,2-diamine-9,10-aminoanthraquinone in polymethylmethacrylate.

The heating temperature T=140oC

Processing time - 30 min

The concentration of 1-aminoanthraquinone material 310-3mol/L.

The bulk conductivity:

original sample - 1,710-15Ω-1m-1(an increase of 700 times)

- processed sample - 1,210-12Ω-1m-1(an increase of 700 times)

The density of the surface charge:

original sample - 5 NC/cm2(increase 7 times)

- processed sample - 35 NC/cm2(increase 7 times)

Example 3.

The introduction of 1-hydroxy-9,10-anthraquinone in polymethylmethacrylate.

The heating temperature T= 140oCSUP>mol/L.

The bulk conductivity of

original sample - 1,710-15Ω-1m-1(decrease 140 times)

- processed sample - 1,210-13Ω-1m-1(decrease 140 times)

The density of the surface charge

original sample - 5 NC/cm2(decrease more than 30 times)

- processed sample is less than 0.15 NC/cm2(decrease more than 30 times)

Example 4.

The introduction of iodine in the polyethylene terephthalate.

The heating temperature T=150oC

The processing time is 20 minutes

The concentration of iodine in the material - 510-3mol/L.

The bulk conductivity:

original sample - 2,310-16Ω-1m-1(increase 24,000 times)

- processed sample - 5,610-12Ω-1m-1(increase 24,000 times)

The density of the surface charge:

- the initial sample is 4.5 NC/cm2(an increase of 56 times)

- processed sample is 250 NC/cm2(an increase of 56 times)

Young's modulus:

original sample - 4510 MPa (without changes (within measurement error))

- processed sample - 4479 MPa (without changes (within measurement error))

Yield strength:

original sample - 111 MPa (without measurements))

Strength:

- the initial sample of 168 MPa (without changes (within measurement error))

- processed sample is 165 MPa (without changes (within measurement error))

Sources of information

1. A. C. SU N 1420675, 1985.

2. A. C. SU N 606602, 1978.

3. Kocherginsky centuries, Vorobiev, A., Skynav C. M. Journal of applied chemistry, I. 68, No. 7, 1995, S. 1111-1115.

4. A. C. SU N 1788601, 1993.

5. EN N 94028725, 1996.

6. A. S. U N 429072, 1974.

The modification of the electrical properties of products of solid polymer dielectrics by introducing impurities in the polymer material, characterized in that the introduction of impurities with donor or acceptor properties carried out from the gas phase at a pressure of 10-1-10-2PA to the concentration of polymeric material (3-5)10-3mol/l, and before the introduction of impurities polymeric material is transferred to highly elastic to plastic state by heating it to a temperature

T = (l,3 - l,6)Tg,

where T is the temperature of the polymer material;

Tg is the glass transition temperature of the polymer material.

 

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