The effect of fractional structure of the granulated nanofiber carbon filler on the electrical properties of epoxy resin composites has been investigated in this article. The conductivity and permittivity of  composite materials has been measured in the frequency range of 100 Hz – 1 MHz. It was shown that  the grain-size distribution of the applied filler effects the electrical properties of epoxy resin / carbon  nanofiber composites

Bannov, A. G.

Krut’ko, E. T.

Kuvshinov, G. G.

Prokopchuk, N. R.

Shashok, Zh. S.

Uvarov, N. F.

Vishnevsky, K. V.

The effect of fractional structure of the granulated nanofiber carbon filler on the electrical properties of epoxy resin composites has been investigated in this article. The conductivity and permittivity of composite materials has been measured in the frequency range of 100 Hz – 1 MHz. It was shown that the grain-size distribution of the applied filler effects the electrical properties of epoxy resin / carbon nanofiber composites

Belarusian State Technological University

Chemistry, Technology of Organic Substances, Materials and Products  27 УДК 537.312  A. G. Bannov, PhD (Engineeging), assistant professor (NSTU); N. F. Uvarov, D. Sc. (Chemistry), professor (NSTU, IHTTM SO RAS); G. G. Kuvshinov, D. Sc. (Engineering), professor (SGU); N. R. Prokopchuk, Corresponding Member of Belarus NAS, D. Sc. (Chemistry),  professor, head of the department (BSTU); E. T. Krut’ko, D. Sc. (Engineering), professor (BSTU); Zh. S. Shashok, PhD (Engineeging), assistant professor (BSTU); K. V. Vishnevsky, PhD (Engineeging), assistant lecturer (BSTU) INFLUENCE OF FRACTIONAL STRUCTURE OF THE GRANULATED NANOFIBROUS  CARBON FILLER ON ELECTROPHYSICAL PROPERTIES OF EPOXY COMPOSITES The effect of fractional structure of the granulated nanofiber carbon filler on the electrical proper-ties of epoxy resin composites has been investigated in this article. The conductivity and permittivity of composite materials has been measured in the frequency range of 100 Hz – 1 MHz. It was shown that the grain-size distribution of the applied filler effects the electrical properties of epoxy resin / carbon nanofiber composites.  Introduction. Carbon nanomaterials are of the great interest for many researchers all over the world. In the number of references in the scientific literature the leading place is occupied by the car-bon nanotubes (CNTS) and carbon nanofibers (CNF).Due to the wide range of interesting proper-ties such as high strength, high electrical and ther-mal conductivity, these types of carbon nanomate-rials have prospects of application in many fields, in particular as catalysts and carriers of catalysts [1, 2], fillers for polymer composites [3–4] electro-chemical sensors [5], electrode materials for super-code-Satoru [6–7] and others. In the recent years, the increasing attention is paid to the study of the properties of composite materials on the basis of CNF, the perspectives of their application are asso-ciated with cheapness and ease of access, which is important in the case of creation of the industrial production of these materials.  Among the wide range of scientific problems of creating polymer composites based on CNF the important issue is to develop a method of produc-ing epoxy composites with improved properties. In particular, the method of producing the composite affects the dispersion of the filler and its distribu-tion in the polymer matrix [8]. In the work [9] the effect of various methods of obtaining epoxy com-posites (mechanical stirring, ultrasonic dispersion in a solvent and epoxy resin) on their electrophysi-cal properties was investigated. In the work [10] it was found that the disper-sion of the filler has a significant impact on the electrophysical properties of the composites. Simi-lar effects have been published by Cardoso and his colleagues in the work [11].  In the work  [12], the authors used two me-thods of obtaining composites using ultrasonic dis-persion UNV in the system solvent – epoxy resin. It was found that the method of introduction of the epoxy resin at receiving the composite significant-ly affects the stealth properties of composites in the field of 8–20 GHz.  In the work [13] the authors use electric fields to produce composites of epoxy resin CNF with anisotropic properties. The formation of the con-ductive network of the filler in the direction of ap-plication of electric field allows to control the elec-trical conductivity of the composites successfully. Unlike most of the works where powdered na-nofibers filters were used, in this work as a filler is used granulated nanofibrous carbon filler . In this paper the influence of the fractional composition of granulated nanofibrous carbon fil-ler on the electrophysical properties of epoxy com-posites was found. The experimental technique. Nanofibrous granular material NWU-1 (Fig. 1) used in  this work was obtained by catalytic decomposition of methane in PI-pilot reactor with vibramicina layer [14].  Fig. 1. The appearance of the granules NWU-1 Micropictures, which were obtained using trans-mission electron microscopy, is shown in Fig. 2. For sample preparation of composite materials was used epoxy resin (ES) of the brand DER 331 (DOW Chemicals Co.) and curing the polyethyle-28 ISSN 1683-0377. Proceedings of BSTU. 2014. No. 4. Chemistry, Organic Substances Technology and Biotechnology nepolyamine (Pepa) (CJSC "Uralkhimplast"). The resin and hardener were mixed in a mass ratio of 6 : 1. A sample NWU-1 was divided into fractions using a set of laboratory sieves. A given fraction of NWU-1 was mixed with ES.   а b  c d Fig. 2. Images of the sample of granular nanofibrous carbon material with different magnification (a–d) The composites samples have been obtained with concentration of NWU-1 (p) 10 wt %. Sepa-rate fractions of NWU-1, as well as their mixtures, were used as filler. For detailed consideration the following samples of composites with different fractional composition of the filler (Table). Fractional composition of the sample of filler  NWU-1 and its concentration in the composite Sample number  Particles size used  in fraction nwu-1, mkm Concentration  of nwu-1 in the composite, wt % 1 63–80 10 2 315–500 10 3 100–315 315–500 6.67 3.33 4 80–100 100–315 3.33 6.67 5 80–100 10 6 <100 10 Frequency dependence of electrical conductivi-ty, dielectric permittivity and tangent of dielectric loss of the composites were determined on the ana-lyzer dielectric properties and impedance Novo-control Beta K at room temperature in the frequen-cy range 0.09 Hz – 1 MHz. Samples of composite materials had a cylin-drical shape. The height and diameter of the sam-ples was 3–5 and 31.4 mm, respectively. The specific volume electrical conductivity was determined by formula (1):  σ h GS⋅= , (1) where σ – the conductivity, Cm/m; G – the sample conductivity, Cm; S – sample are (m2); h – is the sample thickness, m. The dielectric constant was determined by us-ing the expression (2):  0εεC hS⋅= ⋅ ,  (2) where ε – the dielectric constant of the sample; ε0– the permittivity of vacuum, ε0 = 8.85 · 10-12 f/m; С – the capacitance of the sample F. Main part. Because the original sample NWU-1 is a granular material with a particle size in the range of 0.05 to 8 mm, the particle size of this filler can greatly influence the conductivity and permittivity of composites. The conductivity of the composites ES/CNF–1 with a filler different fractional composition with the content of 10 wt % ranged 10–5–10–9 Cm/m The filler in this case is a mixture of larger par-ticles 315–500 mkm with a grain size 100–315 mkm in the proportion of 1 : 2. As the conductivity of the samples No 2 is the worst among all the stu-died compositions, the introduction of the particles with smaller fractions 100–315 mkm into the filler increases the conductivity by reducing the effective  – No. 1; – No. 2; – No. 3; – No. 4;  – No. 5;  – No. 6 Fig. 3. The influence of the fractional composition  of NWU-1 on the electrical conductivity  of the composite ES / NWU-1 When considering samples that were obtained without the using of mixtures of fractions it is seen that the sample with particles of NWU-1 size 10–510–610–710–810–9The electrical conductivity σ, Cm/m 102 103 104 105 106Frequency (f), Hz 20 nm 20 nm 500 nm 2 um Chemistry, Technology of Organic Substances, Materials and Products  29 63–80 mkm possessed the best electrophysical prop-erties. To improve the conductivity of the composites a mixture of coating 80–100 and 100–315 mkm, and 100–315 and 315–500 mkm were used as a filler. The composite with addition of a mixture of frac-tions 100–315 mkm and 315–500 mkm (sample No 3) possessed the highest conductivity.  Figure 4 presents the dependence of the dielec-tric permittivity of the composites from the frac-tional composition of the filler. The dielectric constant (ε) of the composite with the faction 315–500 mkm NWU-1 (sample No. 2) practically doesn’t depend on frequency, that indicates a weak contribution of interfacial polarization due to the formation of low surface interface between matrix and filler. A simi-lar behavior of ε(f) presents in all other samples with addition of fractions 80–100 mkm, <100 mkm and mixture fractions 80–100 and 100–315 mkm. Despite the weak dependence of the dielectric con-stant on frequency, sample No. 1 (contains particles 63–80 mkm) has a higher high-frequency dielec-tric constant ε∞ = 15. Sample No. 3 (filled with a mixture of fractions 100–315 and 315–500 mkm) despite the improved conductivity shows a small high frequency dielectric constant ε∞ = 6 at a concentration of 10 wt % and this value varies slightly with increasing frequency. For the latest composite it is characterised by the power depen-dence of ε(f) in the double logarithmic coordi-nates, indicating a greater contribution of interfa-cial effects in polarization processes. It may indi-cates that the filler in this case forms a large surface interface that contributes to the polariza-tion at low frequencies, and this effect disappears with increasing frequency.   – No. 1;  – No. 2;  – No. 3;  – No. 4;  – No. 5;  – No. 6 Fig. 4. The influence of the fractional composition  of NWU-1 on the dielectric conductivity  of the composite ES / NWU-1 In summary, we note that to increase the con-ductivity of epoxy composites, it is more efficient to use as a filler mixture of particles of NWU-1 size 100–315 mkm and 315–500 mkm with a high-er proportion of fine fraction. To improve the high-frequency dielectric constant is preferable to use filler with a particle size 63–80 mkm. For compari-son, the dielectric constant of the composite with the addition of particles less than 100 microns, with p = 45% (maximum concentration) is ε∞ = 17, which is not much higher than the permeability of the composite with the faction 63–80 mkm (ε∞ = 15) at p = 10%. Thus, selection of the optimal fraction-al composition of NWU-1 can provide a much higher dielectric constant of the composites with relatively low concentrations of filler. In conclusion it should be noted that the use of different fractions of granulated nanofibrous car-bon filler to control the electro-physical properties of epoxy composites is quite effectively. Remem-ber that to apply the material NWU-1 as a filler just the separation into fractions without the use of grinding filler must be used. Conclusion. It was found that the use of a certain fractional composition of nanofibrous car-bon filler is effective for improving the electrical properties against electromagnetic radiation. Usege of a specific fractional composition enables to avoid costly manufacturing operations grinding. References 1. New effective catalysts based on mesopor-ous nanofibrous carbon for selective oxidation of hydrogen sulfide / V. V. Shinkarev [a. o.] // Ap-plied Catalysis B: Environmental. 2009. Vol. 85, No. 3–4. P. 180–191. 2. Nanofibrous carbon with herringbone struc-ture as an effective catalyst of the H2S selective oxidation / V. V. Shinkarev [a. o.] // Carbon. 2010. Vol. 48. No. 7. P. 2004–2012. 3. Carbon nanofibers for composite applica-tions / E. Hammel [a. o.] // Carbon. 2004. Vol. 42. No. 5–6. P. 1153–1158. 4. A review of the fabrication and properties of vapor-grown carbon nanofiber / polymer compo-sites / G. G. Tibbetts [a. o.] // Compos. Sci. Tech-nol. 2007. Vol. 67. No. 7–8. P. 1709–1718. 5. A new electrochemical sensor based on W-doped titania-CNTs composite for detection of pentaclorophenol / W. Q. Zhang [a. o.] // Indian Journal of Chemistry. 2011. Vol. 50A. No. 2.  P. 15–21. 6. Graphene and carbon nanotube composite electrodes for supercapacitors with ultra-high energy density / Q. Cheng [a. o.] // Physical Chemistry Chemical Physics. 2011. Vol. 13, No. 39. P. 17 615–17 624. 101 The  dielectric  constant , ε 102 103 104 105 106Frequency (f), Hz 102 30 ISSN 1683-0377. Proceedings of BSTU. 2014. No. 4. Chemistry, Organic Substances Technology and Biotechnology 7. Lang J., Yan X., Xue Q. Facile preparation and electrochemical characterization of cobalt oxide / multi-walled carbon nanotube composites for supercapacitors // Journal of Power Sources. 2011. Vol. 196. No. 18. P. 7841–7846. 8. Correlations between Percolation Thre-shold, Dispersion State, and Aspect Ratio of Carbon Nanotubes / J. Li [a. o.] // Advanced Functional Materials. 2007. Vol. 17. No. 16.  P. 3207–3215. 9. Effect of the preparation methods on elec-trical properties of epoxy resin / carbon nanofi-ber composites / A. G. Bannov [a. o.] // Nano-technologies in Russia. 2012. Vol. 7. No. 3–4.  P. 169–177. 10. Quantitative evaluation of the dispersion achievable using different preparation methods and DC electrical conductivity of vapor grown carbon nanofiber / epoxy composites / P. Car-doso [a. o.] // Polymer Testing. 2012. Vol. 31. No. 5. P. 697–704. 11. The role of disorder on the AC and DC electrical conductivity of vapour grown carbon nanofibre / epoxy composites / P. Cardoso [a. o.] // Compos. Sci. Technol. 2012. Vol. 72. 2. P. 243–247. 12. Nanni F., Travaglia P., Valentini M. Effect of carbon nanofibres dispersion on the microwave absorbing properties of CNF / epoxy composites // Compos. Sci. Technol. 2009. Vol. 69. No. 3–4.  P. 485–490. 13. Prasse T. W., Cavaille J-Y., Bauhofer W. Electric anisotropy of carbon nanofibre / epoxy resin composites due to electric field induced alignment // Compos. Sci. Technol. 2003. Vol. 63. No. 13. P. 1835–1841. 14. Реализация процесса получения грану-лированного каталитического волокнистого углерода в масштабе пилотного реактора /  С. Г. Заварухин [и др.] // Химическая промыш-ленность. 1998. №. 5. С. 48–52. Received: 20.02 2014  

Influence of fractional structure of the granulated nanofibrous carbon filler on electrophysical properties of epoxy composites

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Influence of fractional structure of the granulated nanofibrous carbon filler on electrophysical properties of epoxy composites

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