A. N. Klyamkina

• Semenov Institute of Chemical Physics

A simple method for the two-stage synthesis in one reactor on one catalyst of heterophase thermoplasticelastomers based on isotactic polypropylene (PP) and an ethylene-propylene copolymer or an ethylene-propylene-1,4-hexadiene terpolymer is developed. The obtained materials, depending on the composition,have good elastomeric properties or behave li...

Polymer composite films of polypropylene and graphene nanoplatelets were subjected to mechanical activation. Electrical current pulses are observed during this process. Fourier transforms of the signals are fitted to Havriliak-Negami model and the Kubo model for multilayer graphene. The calculated frequency dependences of conductivity are in good a...

A phenomenon of change in the frequency of a mechanically activated current was detected for the first time. This phenomenon consists in the fact that electric current pulses produced by a rheological explosion differ in frequency characteristics between a polypropylene-graphene nanoplates composite and the matrix polymer (polypropylene). It was sh...

The polymerization of propylene with small amounts of 1-hexene in the presence of supported titanium–magnesium catalyst containing two internal non-phthalate donors was accomplished. Polypropylene modification with small amounts of 1-hexene affects the thermophysical properties and molecular weight characteristics of the polymers. The activation me...

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-Me2Si(2-Me-4-PhInd)2ZrCl2 activated by methylaluminoxane. The application of binary carbon nanofillers allows one to enhance thermal sta...

This work assessed biodegradation, by Aspergillus, Fusarium, Penicillium and Parengyodontium fungi, of four samples of poly-ε-caprolactone (PCL), three samples of poly-l-lactide (PLA) and one sample of poly-d,l-lactide (DL-PLA) produced by ring-opening polymerization initiated by aluminium complexes of corresponding lactones. Mesophilic fungal stra...

Nanocomposites containing graphene nanoplateletes (GNP) and isotactic polypropylene (PP) were obtained by in situ polymerization. The kinetics of peroxyl radical termination in the obtained nanocomposites was measured by decay of photoinduced chemiluminescence of PP. The concentration of peroxyl radicals was found to decrease significantly, and the...

Two catalytic systems, metallocene-based and Ti-based were used to synthesize by in situ polymerization the composites of polypropylene and few-layer graphene nanoparticles, prepared by chemical or thermal reduction of graphite oxide. The effect of metallocene and titanium catalytic systems on the properties of nanocomposites and distribution of na...

We present a low-frequency (or low-wavenumber) Raman spectroscopy study of isotactic polypropylene, namely the different modifications - α, γ, and smectic, with a degree of crystallinity ranging from 0 to 70 %, as well as of random propylene/1-butene and propylene/1-octene copolymers with the incorporated monomer contents of 5.3 and 19.5 mol % for...

We present Raman structural study of two grades of random propylene/1-octene copolymers with low and high molecular weights and the 1-octene content up to 4.5 mole %. The copolymer spectra are compared with the spectra of the α, γ, and smectic modifications of isotactic polypropylene. Raman investigation has showed that the degree of crystallinity...

The copolymers of propylene and methyl vinyl ketone are synthesized at 60°С by copolymerization in the propylene bulk in the presence of the polymethylaluminoxane-activated metallocene catalysts, namely, the isospecific С2-symmetric metallocene catalyst rac-Me2Si(2-Me-4-PhInd)2ZrCl2 and the syndiospecific Сs-symmetric metallocene catalyst Ph2ССpFlu...

Behavior of the regularity modes of isotactic polypropylene is analyzed in Raman spectra of a number of random propylene/olefin copolymers. The regularity modes at 809, 841, 973, 998, and 1220 cm−1 decrease in intensity with growth of the content of the incorporated monomer. For the lines at 809, 973, and 1220 cm−1 the rate of intensity damping var...

Composite materials of polypropylene, graphene nanoplatelets (GNP) or fullerene C60 were synthesized by in situ polymerization. GNP particles consist of 3–5 graphene layers and have aspect ratio 40. In composites with pristine GNP particles their aspect ratio is 110, whereas ultrasonic processing reduces it to 40–50. This change of aspect ratio of...

Composite materials of polypropylene, graphene nanoplatelets (GNP) or fullerene C 60 were synthesized by in situ polymerization. GNP particles consist of 3 - 5 graphene layers and have aspect ratio 40. In composites with pristine GNP particles their aspect ratio is 110, whereas ultrasonic processing reduces it to 40 - 50. This change of aspect...

New composite materials based on a syndiotactic polypropylene (SPP) and nanosized carbon fill� ers of various types (graphene nanoplates (GNP) and fullerene) are obtained by polymerization in situ. It is shown that the introduction of nanocarbon particles did not lead to a significant decrease in the activity and stereo�specificity of a syndio�spec...

New composite materials based on isotactic PP and fullerene were prepared via in situ polymerization with the use of an isospecific metallocene catalytic system. The stress-strain properties, thermophysical characteristics, and reactivities of composites in reactions of high-temperature decomposition, oxidation, and chemiluminescence were studied....

The principles of the creation of new blend polyolefin elastomers with a controlled complex of properties based on a stereoblock elastomeric PP synthesized in the presence of asymmetric ansa-metallocenes are proposed. Original blend polymer materials with reduced hardness that are based on elastomeric PPs with different characteristics and a 50–70...

In recent years researchers have paid considerable attention to the creation of multifunctional polymer composite materials bearing nanoscale fillers. The introduction of nanoparticles into polymer matrices in relatively small concentrations (reaching 2.5 vol %) makes it possible to produce materials possessing better properties than the initial ma...

In recent years researchers have paid considerable attention to the creation of multifunctional polymer composite materials bearing nanoscale fillers. The introduction of nanoparticles into polymer matrices in relatively small concentrations (reaching 2.5 vol %) makes it possible to produce materials possessing better properties than the initial ma...

This work is devoted to a study of the properties of copolymers of polypropylene with a content of octene units of 1.5-8.4 mol%. A study was made of the kinetics of oxidation of nascent specimens of polypropylene and its copolymers with octene at temperatures of 90-130°C. At all temperatures, both the oxidation rates and the induction periods of ox...

We present Raman study of random copolymers of ethylene and propylene with a number of α-olefins, and investigation of the relationships between the spectral characteristics of the Raman lines and the copolymer structural properties. For both the copolymers we observed rapid decrease in the crystallinity and conformational order as the content of t...

Nascent form of random propylene/1-pentene copolymers was studied for the first time by Raman spectroscopy. For the purpose of detailed interpretation of the copolymer spectra, we investigated Raman spectra of neat PP with low and high crystallinity. It was found that the copolymer Raman spectra depend on the 1-pentene content. We registered the mo...

Nanocomposites of polypropylene and graphene nanoplatelets were synthesized by in situ polymerization in liquid monomer in the presence of highly effective isospecific homogeneous metallocene catalyst. Microstructure, mechanical, dielectric, and thermal properties of composites are presented. X-ray phase analysis data indicate that graphene nanopla...

The copolymerization of propylene with 1-butene and 1-pentene at 60°C in the propylene bulk in the presence of the homogeneous isospecific metallocene catalyst of the C2 symmetry rac-Me2Si(4-Ph-2-MeInd)2ZrCl2 activated by polymethylaluminoxane is studied. Copolymers containing up to 30 mol % 1-butene and up to 10 mol % 1-pentene are synthesized. Fo...

Propylene-vinylcyclohexane copolymers containing 0.02–0.37 mol % vinylcyclohexane are synthesized and characterized; the copolymers are prepared via bulk copolymerization at 60°C in the presence of a metallocene catalyst with the C2 symmetry rac-dimethylsilylidene-bis(2-methyl-4-phenylindenyl)zirconium dichloride activated by polymethylaluminoxane....

Nascent form of random copolymers of propylene with ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene was studied by Raman spectroscopy. The most significant spectral alterations with a change in propylene content were observed in two lines at 809 and 841 cm−1. The first line corresponds to vibrations of polypropylene helical chains in...

The effect of internal and external electron donors on the polymerization of propylene in a liquid monomer or a hydrocarbon diluent (hexane) in the presence of a titanium-magnesium nanocatalyst activated with an organoaluminum compound (triethylaluminum, triisobutylaluminum) and the properties of the resulting PP are studied. The polymerization of...

The polarized Raman spectroscopy is employed in the study of structural modifications in the films of isotactic polypropylene (PP) whose chain contains ethylene, 1-butene, 1-hexene, 1-octene, and 4-metyl-pentene-1, which represents an isomer of 1-hexene. It is demonstrated that the phase and conformational compositions of copolymer molecules depen...

The copolymerization of propylene with 1-octene in liquid propylene is carried out in the presence of a highly active homogeneous ansa-m etallocene catalyst with the C 2-symmetry rac-Me2Si(4-Ph-2- MeInd)2ZrCl2 activated by methyl aluminoxane and in the presence of ansa- metallocene C4H6Si(2-Et4- PhInd)2ZrCl2 (rac: meso = 2:1) supported on silica ge...

Isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP) nanocomposites containing 0.1–3.5wt.% multi-wall carbon nanotubes (MWCNTs) have been synthesized via in situ polymerization method with the use of C2- and Cs- symmetry zirconocenes activated by methylaluminoxane (MAO) in liquid propylene medium. Fracture morphology studies by SEM re...

Studies devoted to the homo-and copolymerization of propylene with ethylene and higher olefins (1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene) in liquid propylene under the action of homogeneous metallocene catalysts of various types are surveyed in brief. The main kinetic features of the processes and the properties of the polymers are discusse...

Multiwall carbon nanotubes (MWCNTs) have been functionalized via addition of undecyl (C11-) radicals generated by thermal decomposition of lauroyl peroxide. The functionalized MWCNTs (C11-MWCNTs) were characterized by Raman, IR spectroscopy, and thermogravimetric analysis (TGA). Isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP) nan...

The Raman spectra of the ethylene-propylene copolymers (EPC) synthesized using new metallocene catalytic systems and the polypropylene/polyethylene/diblockcopolymer of propylene and ethylene (PP/PE/DBC) blends obtained using the sequential polymerization are studied. The copolymer and reactor blend spectra are analyzed using the Raman spectra of a...

Isotactic polypropylene and elastomeric stereoblock polypropylene nanocomposites containing 0.1-3.5 wt % multiwall carbon nanotubes (MWCNTs) have been synthesized via the in situ polymerization approach using MAO-activated C2- and C1-symmetry ansa-zirconocenes, a technique that has not been previously reported in literature. Fracture morphology exa...

Propylene copolymerization with 1-hexene and 4-methyl-1-pentene in liquid propylene medium in presence of MAO-activated C2-symmetry ansa-zirconocene rac-Me2Si(4-Ph-2-MeInd)2ZrCl2 was studied. Random copolymers of propylene with 1-hexene and 4-methyl-1-pentene content up to 7mol % were obtained at 60°C. General kinetic characteristics of propylene/h...

The polymerization and copolymerization of vinylcyclohexane with α-olefins in the presence of several heterogeneous and homogeneous catalytic systems were studied. It was shown that, with respect to activity in the polymerization of vinylcyclohexane, the tested catalysts can be arranged in the following order: α-TiCl3 < titanium-magnesium catalyst...

The copolymerization of propylene and 1-hexene initiated by isospecific catalytic systems containing ansa-metallocene complexes with a C2 symmetry, rac-Me2Si(Ind)2ZrCl2 and rac-Me 2Si(4-Ph-2-Me-Ind)2ZrCl2, and a syndiospecific catalytic system based on a Cs symmetric complex Ph 2C(Cp)(Flu)ZrCl2 was studied. Polymethylaluminoxane or a mixture of pol...

The polymerization of 3-methyl-1-butene with heterogeneous titanium-magnesium and homogeneous metallocene catalysts differing in the type of symmetry, such as Me2C(3-Me-Cp)(Flu)ZrCl2 (C1 symmetry) and Ph2C(Cp)(Flu)ZrCl2 (Cs symmetry), was studied. The activity of metallocene catalysts is much higher than that of titanium-magnesium systems under com...

Propylene/ethylene copolymers were prepared over two complex catalyst systems: (i) an AlEt3-activated MgCl2-supported titanium catalyst TiCl4/MgCl2 with dibutyl phthalate and propyltrimethoxysilane used as respectively internal and external donors and (ii) two methylaluminoxane (MAO)-activated, unsupported zirconocene catalyst systems differing in...

The kinetic parameters of the synthesis of iso-, syndio-, hemiisotactic, and stereoblock PP in a liquid propylene using a series of ansa-metallocenes with C1, C2, and C5 symmetries activated by methylalumin-oxane were studied. For several metallocenes, the effect of hydrogen on the activity and molecular mass characteristics of PP was assessed. The...

The activity and stereospecificity of the catalytic system TiCl4-Et2AlCl of propylene polymerization was studied in relation to the nature of carbon-containing supports like graphite, fullerene C60, anthracene, polyacetylene, and fullerene soot. Graphite and fullerene soot were most effective supports. Isotactic polypropylene was formed at a high r...

Electrophysical and physicomechanical properties of polymerizationally filled composites containing natural or synthetic graphite were compared with those of composites prepared by blending. A more uniform distribution of graphite particles in polymerizationally filled composites resulted in a linear dependence of resistance on sample length; this...