One of the basic directions of the Laboratory's activity is the study of properties of thermoplastic materials and development of novel composite materials with required characteristics. Research methods used in Laboratory are as follows:

• sub-molecular structure study;
• measurement of the main electric characteristics of polymeric materials (specific surface and volume resistivities, permittivity and tangent delta);
• measurement of dielectric strength;
• measurement of partial discharge activity;
• measurement of mechanical properties (tensile strength, tensile elongation, compression strength);
• treeing characteristics;
• differential scanning calorimetry (DSC) and IR-spectroscopy.

In our Laboratory there is a program-controlled optical complex including microscope, optical scanner and computer for the study of sub-molecular structure of thermoplastics.

Dielectric spectroscopy (measurements of the permittivity and tangent delta) over the frequency range from 100 mHz to 1 MHz at different temperatures is carried out by means of Solartron Analytical Instrument.

Complete set of experimental setups for the measurement dielectric strength under DC, AC and impulse voltage (micro- and millisecond duration) and mechanical characteristics is represented in Laboratory.

On-line study of the treeing phenomenon and influence of residual mechanical strain on the treeing characteristics is performed by means of the optical setup (polariscope). The optical setup includes an additional electrical channel for the study of partial discharge activity during the treeing inception and growth.

Differential scanning calorimetry and IR-spectroscopy are excellence instruments for the study of characteristics of new composite nano-materials on the basis of polymeric dielectrics. Data obtained by means of these methods allows a molecular structure of studied materials to be studied.

Temperature intervals of melting and decomposition for thermoplastics and new composite nano-materials can be obtained by means of DSC method (analyzer Q600 �TA Instruments�).

IR-spectra for thermoplastic materials can be measured by means of IR spectrometer (Avatar 370 �Thermo Electron Corporation�).

References

1. Gefle O.S., Lebedev S.M., Pokholkov Y.P. Barrier effect in dielectrics, Tomsk: TML-press, 2007.
2. Lebedev S.M., Vazhov V.F., Ushakov V.Y. Effect of space charge in polymers under long-term electric field application, Russian J. Tech. Phis., No 4, pp. 752-754, 1983.
3. Lebedev S.M. Estimation of polymeric insulation life-time by means of internal electric field strength, Russian J. Electricity, No 6, pp. 57-58, 1987.
4. Gefle O.S., Lebedev S.M. and Uschakov V.Y. The mechanism of the barrier effect in solid dielectrics, J. Phys. D: Appl. Phys., Vol. 30, pp. 3267-3273, 1997.
5. Gefle O.S., Lebedev S.M. The anomalous treeing resistance of proton-irradiated PMMA, J. Phys. D: Appl. Phys., Vol. 30, pp. 1225-1227, 1997.
6. Lebedev S.M., Agoris D.P., Vitellas I. and Pokholkov Yu.P. The role of polarization in the breakdown of an air gap with barrier, J. Phys. D: Appl. Phys., Vol. 34, pp. 1271-1275, 2001.
7. Agoris D.P., Vitellas I., Gefle O.S., Lebedev S.M. and Pokholkov Yu.P. The barrier effect in three-layer solid dielectrics in quasi-uniform electric field, J. Phys. D: Appl. Phys., Vol. 34, pp. 3485-3491, 2001.
8. Gefle O.S., Lebedev S.M., Pokholkov Yu.P., Agoris D.P. and Vitellas I. Influence of polarisation on breakdown strength of polymeric composite dielectrics, IEE Proc.-Sci. Meas . Technol., Vol. 148, pp. 125-128, 2001.
9. Gefle O.S., Lebedev S.M., Pokholkov Yu.P., Agoris D.P. and Vitellas I. Behaviour of multilayer PET polymer film insulation in high electric field, IEE Proc.-Sci. Meas. Technol., Vol. 151, pp. 273-277, 2004.
10. Gefle O.S., Lebedev S.M., Pokholkov Yu.P., Gockenbach E. and Borsi H. Tree-inception in PMMA with a barrier, J. Phys. D: Appl. Phys., Vol. 37, pp. 2318-2322, 2004.
11. Lebedev S. M., Gefle O. S., Pokholkov Y. P., et al. Influence of high-permittivity barriers on PD activity in three-layer dielectrics, J. Phys. D: Appl. Phys., Vol. 37, pp. 3155-3159, 2004.
12. Lebedev S.M., Volokhin V.A., Shmakov B.V., Cherkashina E.I. Technology for manufacture of products by injection molding under low pressure, Russian J. Plastics, No 12, pp. 55-56, 2004.
13. Gefle O.S., Lebedev S.M., Pokholkov Yu.P. The barrier effect in dielectrics. The role of interfaces in the breakdown of inhomogeneous dielectrics, IEEE Trans. DEI, Vol. 12, pp. 537-555 , 2005.
14. Gefle O.S., Lebedev S.M., Tkachenko S.N. Behaviour of polymeric composites filled with ferroelectric ceramic powder under electric field, Proc. of Tomsk Polytechnic University, Vol. 308, No 4, pp. 64-68, 2005.
15. Gefle O.S., Lebedev S.M., Tkachenko S.N. Application of the dielectric spectroscopy method for assessing polymeric dielectrics state under electric field, Proc. of Tomsk Polytechnic University, Vol. 309, No 2, pp. 114-117, 2006.
16. Gefle O.S., Lebedev S.M. Effect of morphology, proton irradiation and pre-stressing on the breakdown of LDPE, IEEE Trans. DEI, Vol. 13, pp. 788-794 , 2006.
17. Lebedev S.M., Volokhin V.A., Shmakov B.V., Matin P.A. Technology for manufacture of high voltage insulation made of polycarbonate resins, Proc. of Tomsk Polytechnic University, Vol., 309, No 2, pp. 121-125, 2006.
18. Gefle O.S., Lebedev S.M., Pokholkov Yu.P. Frequency spectra of the complex permittivity of composite dielectrics on the basis of polyvinylidene fluoride, Proc. of Tomsk Polytechnic Universit , Vol., 310, No 1, pp. 87-91, 2007.
19. Tkachenko S.N., Gefle O.S., Lebedev S.M. Influence of modifying addition of nano-powder of Ni on the main electric characteristics of polyvinylidene fluoride, Proc. of Tomsk Polytechnic University, Vol., 310, No 3, pp. 52-56, 2007.
20. Volokhin V.A., Gefle O.S., Lebedev S.M. Influence of residual mechanical strain on the treeing process in polymeric insulation, Russian J. Plastics, No 7, pp. 19-22, 2007.