Boris Bulgakov

Copolymerization of 5-(trimethylsilyl)norbornene and 5-ethylidene-2-norbornene

Addition and metathesis copolymerization of 5-(trimethylsilyl)norbornene (TMSNB) and 5-ethylidene-2-norbornene (ENB) has been studied. High-molecular-weight metathesis copolymers have been obtained on the first-generation Grubbs catalyst based on the Ru carbene complex Cl2Ru(=CHPh)(PCy3)2 with nearly quantitative yields. Addition copolymerization has been carried out on the Ni(II) naphthenatemethylaluminoxane (MAO) catalytic system. In both cases copolymerization proceeded without participation of ethylidene double bond. Copolymers of this type are promising ones for manufacturing stable highly permeable polymeric membranes, since they are capable for crosslinking.

Phthalonitrile-carbon fiber composites produced by vacuum infusion process

High-temperature carbon fiber-reinforced plastics based on phthalonitrile resins are obtained for the first time by vacuum infusion process. For this purpose, formulations based on low-melting bis(3-(3,4-dicyanophenoxy)phenyl) phenyl phosphate monomer in combination with 1,3-bis(3,4-dicyanophenoxy)benzene and 4-[3-(prop-2-yn-1-yloxy)phenoxy]benzene-1,2-dicarbonitrile were developed. Resin viscosities η ≤ 600 mPa·s were suitable for VIP and at the same time the thermal and mechanical properties of the cured matrices were in high level featured to phthalonitriles (HDT ≥ 420℃, E ≥ 5.1 GPa). CFRP samples were manufactured by vacuum infusion process with carbon fabric and demonstrated thermal stability over 400℃ and a change of mechanical properties by less than 10% at 300℃. Present results sufficiently extend the application field of phthalonitriles as matrices for complex-shape high temperature composite parts in aerospace or high-temperature composite tooling for PEEK-like thermoplastics processing.

Mechanical and physicochemical properties of matrices for fiber reinforced plastics based on low-melting phthalonitrile monomers

The mechanical properties of cured phthalonitrile matrices for fiber reinforced plastics (FRP) based on low-melting phenylmethylsilanediyl-bis[oxymethylene(1,4-phenylene-4’-oxyphthalodinitrile)] (1) or its mixture with 1,3-phenylene-bis(oxy-4-phthalodinitrile) (2, comonomer) were studied. The flexural strength, Young’s modulus, fracture toughness, and some other characteristics of the cured resins based on monomer 1 (PN-1) and the mixture of monomers 1 and 2 (PN-1m) were determined. It is noted that the PN-1 resin can be processed by vacuum infusion and the PN-1m resin can be processed by compression injection molding. The developed resins are promising as materials for high-tech aerospace applications.

Thermally stable phthalonitrile matrixes containing siloxane fragments

New low-melting phthalonitrile monomers suitable for the production of high-temperature matrixes for polymer composite materials are synthesized. After the introduction of siloxane bridges into a monomer, the glass-transition temperature decreases to–1–27°С, depending on the type of substituent at the silicon atom. These compounds are found to be sufficiently hydrolytically stable, despite the presence of sensitive siloxane bonds. The cured resin retain properties featured to the class of phthalonitriles, such as a high onset tеmperature of degradation (>530°С in argon), a high heat deflection temperature (>420°С), and char yield. The considered compounds make it possible to widen the temperature window for processing of phthalonitrile resins without any change in the properties of the final material.

Dynamic and Static Mechanical Properties of Crosslinked Polymer Matrices: Multiscale Simulations and Experiments

We studied the static and dynamic mechanical properties of crosslinked polymer matrices using multiscale simulations and experiments. We continued to develop the multiscale methodology for generating atomistic polymer networks, and applied it to the case of phthalonitrile resin. The mechanical properties of the resulting networks were analyzed using atomistic molecular dynamics (MD) and dissipative particle dynamics (DPD). The Young’s and storage moduli increased with conversion, due both to the appearance of a network of covalent bonds, and to freezing of degrees of freedom and lowering of the glass transition temperature during crosslinking. The simulations’ data showed good quantitative agreement with experimental dynamic mechanical analysis measurements at temperatures below the glass transition. The data obtained in MD and DPD simulations at elevated temperatures were conformable. This makes it possible to use the suggested approach for the prediction of mechanical properties of a broad range of polymer matrices, including ones with high structural heterogeneity.

Synthesis and metathesis polymerization of fluorine-containing tricyclononenes

Herein the synthesis of a new series of fluorine containing tricyclononenes using [2σ+2σ+2π]-cycloaddition of quadricyclane with fluorine containing alkenes is described. According to the experiment the reactivity of fluorine containing alkenes in [2σ+2σ+2π]-cycloaddition reaction was established. The obtained cycloadducts were successfully involved in ring-opening metathesis polymerization on Ru-based catalytic systems. The obtained polymers were glassy and amorphous. The investigation of gas-transport properties of the new materials with improved selectivity towards different pairs of gases was executed.Herein the synthesis of a new series of fluorine containing tricyclononenes using [2σ+2σ+2π]-cycloaddition of quadricyclane with fluorine containing alkenes is described. According to the experiment the reactivity of fluorine containing alkenes in [2σ+2σ+2π]-cycloaddition reaction was established. The obtained cycloadducts were successfully involved in ring-opening metathesis polymerization on Ru-based catalytic systems. The obtained polymers were glassy and amorphous. The investigation of gas-transport properties of the new materials with improved selectivity towards different pairs of gases was executed.

Assessment of water pipes durability under pressure surge

Surge phenomenon occurs on the pipeline by the closing valve or pump suddenly lost power. Due to the complexity of the water hammer simulation, previous researches have only considered water hammer on the single pipe or calculation of some positions on water pipe network, it have not been analysis for all of pipe on the water distribution systems. Simulation of water hammer due to closing valve on water distribution system and the influence level of pressure surge is evaluated at the defects on pipe. Water hammer on water supply pipe network are simulated by Water HAMMER software academic version and the capacity of defects are calculated by SINTAP. SINTAP developed from Brite-Euram projects in Brussels-Belgium with the aim to develop a process for assessing the integrity of the structure for the European industry. Based on the principle of mechanical fault, indicating the size of defects in materials affect the load capacity of the product in the course of work, the process has proposed setting up the diagram to fatigue assessment defect (FAD). The methods are applied for water pipe networks of Lien Chieu district, Da Nang city, Viet Nam, the results show the affected area of wave pressure by closing the valve and thereby assess the greatest pressure surge effect to corroded pipe. The SINTAP standard and finite element mesh analysis at the defect during the occurrence of pressure surge which will accurately assess the bearing capacity of the old pipes. This is one of the bases to predict the leakage locations on the water distribution systems. Amount of water hammer when identified on the water supply networks are decreasing due to local losses at the nodes as well as the friction with pipe wall, so this paper adequately simulate water hammer phenomena applying for actual water distribution systems. The research verified that pipe wall with defect is damaged under the pressure surge value.

Hydrolysis rate constants and activation parameters for phosphate- and phosphonate-bridged phthalonitrile monomers under acid, neutral and alkali conditions

Hydrolysis data for Bis(3-(3,4-dicyanophenoxy)phenyl) phenyl phosphate and Bis(3-(3,4-dicyanophenoxy)phenyl) phenylphosphonate under pH 4, 7 and 10 are presented. Conversion/time plots collected by HPLC analysis, typical chromatograms and NMR spectra of the reactions products are given. Pseudo-first order rate constants are determined for both substrates at 25, 50 and 80 °C. Activation parameters were calculated from Arrhenius equation.