200 ISSN 1560-0904, Polymer Science, Series B, 2019, Vol. 61, No. 2, pp. 200–214. © Pleiades Publishing, Ltd., 2019. Russian Text © O.M. Palaznik, P.M. Nedorezova, S.V. Pol’shchikov, A.N. Klyamkina, V.G. Shevchenko, V.G. Krasheninnikov, T.V. Monakhova, A.A. Arbuzov, 2019, published in Vysokomolekulyarnye Soedineniya, Seriya B, 2019, Vol. 61, No. 2, pp. 144–160. Production by In Situ Polymerization and Properties of Composite Materials Based on Polypropylene and Hybrid Carbon Nanofillers O. M. Palaznik a , P. M. Nedorezova a, *, S. V. Pol’shchikov a , A. N. Klyamkina a , V. G. Shevchenko b , V. G. Krasheninnikov a , T. V. Monakhova c , and A. A. Arbuzov d a Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, 119991 Russia b Institute of Synthetic Polymeric Materials, Russian Academy of Sciences, Moscow, 117393 Russia c Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334 Russia d Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia *e-mail: polned@mail.ru Received April 26, 2018; revised September 10, 2018; accepted September 24, 2018 Abstract—Composites based on polypropylene and binary fillers (graphene particles together with carbon nanotubes) are synthesized by in situ polymerization with the use of a homogeneous isospecific metallocene catalyst rac-Me 2 Si(2-Me-4-PhInd) 2 ZrCl 2 activated by methylaluminoxane. The application of binary car- bon nanofillers allows one to enhance thermal stability and thermo-oxidative resistance of materials and to decrease the percolation threshold. It is shown that a close level of conductivity is achieved in the case of a binary filler at a significantly lower concentration. The resulting polymer composites can be applied as anti- static materials, shields and filters of electromagnetic radiation of the corresponding range, and semiconduct- ing layers in power cables. DOI: 10.1134/S1560090419020088 INTRODUCTION The addition of various fillers to the polymer matrix is one of the efficient methods to modify the properties of materials. A great amount of attention is given here to the development of nanocomposites with the use of functional nanofillers and polymer matrices of different type, including polyolefins [1–3]. The modification of polyolefins via the introduction of nanoscale fillers can improve the set of functional properties: increase the electrophysical characteris- tics, thermal conductivity, heat resistance, and barrier characteristics. Carbon nanoparticles, including graphene ones, are considered promising fillers of polymers. Intro- duction of a small amount of graphene particles into polymers significantly changes their properties and opens the ways to create multifunctional materials with considerably improved characteristics [3–8]. The combination of different carbon fillers is an effective approach to designing polymer composites. A noticeable increase in conductivity with the use of multiwall carbon nanotubes (0.5–1.0 wt %) and car- bon black or graphite instead of individual fillers was described in [9]. In accordance with the authors of [9], this observation implies that nanotubes are involved in the formation of conductive carbon black or graphite networks. The interest of researchers in hybrid materi- als obtained via the combination of graphene nano- plates and carbon nanotubes as polymer fillers is both due to the possibility to better distribute nanoplates and due to the synergetic effect of some composite properties [10–13]. It was shown that the combination of two-dimensional graphene and one-dimensional nanotubes into a three-dimensional hybrid material makes it possible to obtain polymer composites with renewed characteristics [14, 15]. The improvement of polymer composite properties using hybrid fillers based on graphene nanoplates and carbon nanotubes may be connected both with the possibility to further exfoliate the plates and with the appearance of interac- tion of hybrid carbon nanoparticles with each other and a polymer matrix to give rise to a three-dimen- sional network; this is explained by the formation of π–π interaction between carbon fillers and a polymer, for example, polystyrene containing phenyl rings [15, 16]. It is shown, that in the presence of such hybrid fillers owing to interfacial interaction between them and the polymer matrix, the degree of order of poly- mer segments (polydivinylsiloxane) grows [17]. The improvement of some properties of the composites COMPOSITES