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Section 6. Materials Science
Mirzakhmedov Batir Husniddinovich, Tashkent State Technical University, Ph.D., head of Scientific-research section E-mail: b_mirzakhmedov@rambler.ru Begmatov Shavkat Ernestovich, Tashkent State Technical University, Associate Professor
Influence of technological parameters of polarization on the electrical properties composite of polymeric materials
Abstract: The article examines the impact of modifications to the physical properties of composite polymer materials. It is shown that constant exposure to high electric field produces composite polymeric materials with improved electro physical properties.
Keywords: composite polymer materials, epoxy resin, physical modification, a constant electric field, electric tension, polarization.
The development of technology advances increasingly acute problem of creating materials, the structure of which the direction is organized under the influence of operational factors. For the directional changes in the structure and properties of composite polymer materials (CPM) used various methods of physical modifications. One of the promising directions in the solution of this problem is the use of physical fields — electric, magnetic, nuclear, etc.
Currently, for the modification of polymers and fillers in the preparation and processing of CPM are increasingly using physical methods of influence, providing the activation materials and their high level of performance. In many cases, the processes of obtaining the CPM under the influence of physical fields accompanied by deformation and electrical phenomena that lead to the electrification and change the properties of the polymer system. Occurrence of excessive uncompensated charge and polarization determines the system to an electret state, which significantly affects the electrical, mechanical and other properties of the polymers. Rational use of the electret state as a means of regulating the interaction between the components in the preparation of composites and performance properties of the CPM involves large reserves of increase of efficiency of application of polymeric materials in the technique [1].
Due to the orientation of the segments of the macromolecules in polarized polymers there occur orientation phenomena affecting the electrical properties of polymers. At the same time there is a change of structure, consisting in ordering the structure, strengthening intermolecular interactions and increase the degree of cure. All this leads to an improvement in the electrical properties, and increase of physical and mechanical properties of the CPM [2].
To determine the effect of polarization on the properties of polymeric materials there have been studied electrical properties depending on CPM, epoxy resin ED-16 and furan-epoxy resin FAED-20, the electric field intensity and polarization time during curing in a static electric field. As seen from the results of research (Figure 1), values pv and ps polymeric coatings based on epoxy binder with increasing intensity of the polarizing field, with constant polarization time tp=30 min. it increases exponentially and reaches limits when Ep=4,5-5,0 kV/cm. Apparently, this is due to the increase in structural ordering of the polymer coating on the growth of the electric field, which leads to an increase in the degree of crosslinking, which subsequently reach the limit values.
Changes in tgS and £ epoxy coatings have the opposite character with increasing intensity of the polarizing field (Figure 2). Dielectric loss tgS monotonically decreasies and
reaches a minimum value at E =5-6 kV/cm, whereas the
p '
permittivity of £ increases monotonically, approaching the limit values for electric field Ep=4,5-5,0 kV/cm. When the polarization electric field acting on the segments of the macromolecules leads to an orientation relative to each other, and consequently leads to reduction of tgS. The higher the intensity of the polarizing field, the more the degree of orientation and the lower the value of tgS. Furthermore, an increase in the amount of structuring polymer coating and the stiffness of the spatial structure with increasing quantities Ep leads to reduced mobility of macromolecular segments and hence the dielectric loss. Also, the findings suggest the existence of residual polarization responsible for the relatively high £ and low dielectric loss tgS polarization at a given temperature Tp. Changes pv, ps, tgS and £ in dependence on the strength of the polarizing field coating resin FAED-20 have a similar charac-
Section 6. Materials Science
ter. As seen from the results of research (Figure 1 and 2), with an increase in E observed monotonic increase values pv ps and
igp v
16,5 -|
16 -
15,5
15
a)
£ polymer coatings and reduced tgS to the limits and at the same time the value of Ep is within 5,0-5,5 kV/cm.
igpv 6)
17 -i
16,5
16 -
15,5 -
15
3
5En, KV/cm
0
1
3
5En, KV/cm
Fig. 1. Dependence of lgpv and lgps samples CPM ased on the ED-16 (a) and FAED-20 (b) the strength of the polarizing field
Figure 3 and 4 show the results of a study based on electrical properties of polymer coatings on the basis of ED-16 and FAED-20 of the polarization time tp at a constant value of the electric field strength (Ep=5,0 kV/cm). As seen from Figure 3, with increasing polarization time tp samples by curing them in an electric field, a specific volume pv and specific surface ps resistance of coatings based on resin ED-16 exponentially increases and at t =30-40 min reach the limit values. A further increase in
a)
6,5
6 -
5,5
4,5 ■
3,5
tp does not lead to a noticeable increase pv and ps coatings. Obviously, this can be explained by the fact that the processes of ordering of supramolecular structure of the polymer, creating a centered state, increasing structural uniformity, occurring under the influence of a constant electric field in epoxy coatings is substantially complete at this time and will not change significantly as a result of a sharp increase in the viscosity of the polymer.
2 6) tgS* 102
2,5 i
2 -
1,5 -
0,5
ED-16
-- -- FAED-20
5Ep, KV/cm
1 Ep, KV/cm
Fig. 2. Dependence of e (a) and tgS (b) samples CPM the strength of the polarizing field
Changes of tgS and £ polymeric coatings based on epoxy binder, and are not linear (Figure 3). If tgS monotonically decreasies, it reaches a minimum stable value, the £, on the contrary, increasing up to the maximum limits at t =30-40 min.
In the works [3, 4], also noted the increase in £ upon curing of organic substances in an electric field. The effect is attributed to the formation of dipoles associates — polar groups. The increase £ in the formation of electrets in strong fields, explain sometimes the increasing number of charge carriers in the polymer as a result of the injection or ionization.
0
1
E
5
1
4
0
0
1
3
0
1
3
lgp
16,5
16 -
15,5
15
a)
0 10 20 30
lgp
17 i
16,5
16
15,5 -
15
6)
tp, min.
30
60 90
tp, min.
Fig. 3. Dependence of lgpv and lgps samples CPM based on the ED-16 (a)
and FAED-20 (b) from the polarization time (Ep=5 kV/cm)
5 -4 < 3 -2 -
£.
tgS*102
a)
£,
tgS*l02
6)
--£ -- -■ tgd
10
20
30
tp, min.
30
60
90 tp, min.
Fig. 4. Dependence of e and tgS samples CPM based on the ED-16 (a) and FAED-20 (b) from the polarization time (Ep=5 kV/cm)
The nature of the changes of pv ps, tgS and £ polymer Thus, exposure to constant high electric field produces
coatings on the basis of furan-epoxy binder are similar (Figure polymer coatings on the basis of ED-16 and FAED-20 3 and 4), but the effective time of processing the samples in a with improved electro-indices, indicating that optimization constant electric field is tp = 90-100 min., due to a larger value of the structure of polymers. of survival time furan-epoxy resin.
References:
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2. Mirzakhmedov B.H., Negmatov S.S., Guliamov G. Changes in physical and mechanical properties of composite polymer materials when elektretication. Materials RNTK "Composite materials on the basis of technological waste and local raw materials: composition, properties and applications" Tashkent, 2010, April 15-16. P. 135-136.
3. Zakrevskii V.A., Pakhotin V.A. //Vysokomol.soed, 1981. - T. A23. №3. P. 658-662.
4. Lewis T.J. 1976 Ann.Rep.Conf.Electric.Insul. and Diel.Phenom. NAS, Washington, 1978. - P. 533-561.
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2
1
1
0
0
0
0
