The calculation scheme is proposed for analyzing the effect of pressure on the permeability of various gases through polymeric membranes. The calculation scheme is based on the proposed equation, in which the activation energy of the permeability process decreases under the action of pressure according to a power law. The adequacy of the calculation scheme was verified on the example of CO2 permeability through polyimide-based membranes. A good agreement was found between the calculated and experimental data on the increase in permeability with increasing pressure. The performance of the scheme was also tested using the example of three polyimides for two cases-growth and non-monotonic change in permeability. The decrease in permeability and the absence of dependence on pressure are analyzed.

-The approach to the prediction of permeability of polymer membranes based on polyimides and polyamidoimides towards helium is described. According to the approach, the activation energy of helium penetration is expressed by a relationship involving the van der Waals volume of the repeat unit and a set of atomic parameters characterizing the contribution of each of the atoms and intermolecular interaction types into the value of activation energy. The contributions of the imide cycles, type of the connection (meta-, para-, or ortho-), and of the CF3, CH3, CO, Cl, F, and SO2 polar groups have been accounted for. Repeated solution of the redundant set of equations obtained on the basis of the proposed relationship has afforded the parameters giving the correspondence of the calculated values and the experimental data on the membranes permeability with correlation coefficient 0.965. Hence, the possibility to search for the structures of polyimides and polyamidoimides with the target permeability without laborious and expensive experiments has been demonstrated.

The stress-optical coefficient C σ of copolymers based on cured epoxy resins has been calculated. Calculations were made for epoxy resins based on bisphenol A and aliphatic and aromatic diamines. The C σ values are in the range of 91.6÷103 weight percent. All calculations were carried out using the Cascade computer program (developed by INEOS RAS). The investigated structures of cured epoxy resins are obtained from industrial components. High C σ values make it possible to confidently use the mentioned network polymers in the photoelasticity method, from which models of full-scale building structures can be made.

Изложен подход к прогнозированию проницаемости для гелия полимерных мембран на основе полиимидов и полиамидоимидов различного строения. Согласно этому подходу, энергия активации процесса проникновения гелия описывается соотношением, в которое входят ван-дер-ваальсов объем повторяющегося звена полимера и набор атомных констант, характеризующих вклад каждого атома и типа межмолекулярного взаимодействия в величину энергии активации. Учитывается вклад имидных циклов, количество ароматических ядер и тип присоединения ( мета -, пара -, орто -), вклад полярных групп CF 3 , CH 3 , CO, Cl, F, SO 2 . Неоднократное решение избыточной системы уравнений, построенной на основе предложенного соотношения, позволило определить константы, приводящие к согласию расчетных и экспериментальных данных по проницаемости мембран с коэффициентом корреляции 0.965. Таким образом, показана возможность поиска структур полиимидов и полиамидоимидов с заданной проницаемостью для гелия без длительных и дорогостоящих экспериментов.

Diagrams of compatibility of water permeability with glass transition temperature, density, and cohesion energy are constructed. The computer program “Cascade”, INEOS RAS was used. Polyolefins, vinyl polymers, and polycarbonates were analyzed. Compatibility diagrams are constructed for the areas of lowest and highest water permeability for different classes of polymers. For polyolefins and vinyl polymers, the lowest water permeability is selected in the range from 0 to 100 barrer, and the highest water permeability is from 1000 to 2000 barrer. For polycarbonates, the intervals from 0 to 70 barrer and from 3000 to 7000 barrer are selected. These diagrams allow you to select polymers that meet the specified values of density, cohesion energy, glass transition temperature, and the onset of temperature of intense thermal degradation.

One of the possible approaches to the analysis of a physical mechanism of time dependence for the resistance coefficients of materials is suggested. The material durability at the constant stress is described using the Zhurkov and Gul' equations and the durability at the alternating stress—using the Bailey criterion. The low strains lead to structuring of a material that is reflected in a reduction of the structure-sensitive coefficient in these equations. This affords 20% increase in the durability. The dependence of the resistance coefficient assumes an extremal character; the maximum is observed at the time to rupture lg tr ≈ 2 (s).

The materials based on wood-polymer composites (WPC) in the form of decking boards are produced, in which wood filler is partially replaced by mineral one. WPC materials manufactured by Savewood using a matrix polymer of polyvinyl chloride (PVC) have good mechanical properties, low abrasion and satisfactory resistance to climatic influences. However, they have relatively high water absorption, the task of reducing which is relevant not only in Russia, but also in other countries where there are constructions of facilities operating in outdoor environmental conditions. The modification of such materials in this work was carried out by replacing part of the wood filler with the mineral filler, which is CaCO3 (chalk). Partial replacement of wood flour with mineral filler resulted in a marked reduction in swelling from 1.25 to 0.01%. In this case, the modulus of elasticity is increased from 2260 to 2880 MPa, tensile strength from 30.5 to values of 16.7 ÷ 32 MPa. The specific impact strength varies from 8.90 to 7.74 kJ/m2. The optimal ratio of wood and mineral fillers is 60/40%.

The essence of the work lies in the theoretical analysis of the influence of size distribution of nanoparticles in polymer nanocomposites on the glass transition temperature Tg and coefficient of thermal expansion CTE. Both of these characteristics are important for building materials containing polymers. If the values of these characteristics exceed the allowable value, the material will soften and you should not alter its size. Methods: used the Poisson distribution applied to the radius of the nanoparticles. The analysis is performed at the expected mean values of 5 and 10 nm. As object of research used in the cured epoxy resin filled with nanoparticles of SiO2. The surface modified nanoparticles grafted polar groups possessing a dipole-dipole interaction and hydrogen bonds. The analysis is based on previously obtained relationships connecting the Tg and CTE with a set of atomic physical constants. This set depends on the chemical structure of the repeating unit of the polymer or molecular fragment of a polymer network. Among these constants, Van-der-Waals volume and the energy of the dispersion interaction of each atom, as well as energy dipole-dipole interaction or hydrogen bonds to polar groups. The results of the study: they consist in the fact that the dependencies of Tg and CTE on the expected mean radius of nanoparticles are obtained. Considered part of the epoxy resin will be cured with usual methylhydrophthalic anhydride and another part of the epoxy resin will be cured with anhydride-modifier. The formulas for quantitative assessment of the values of Tg and CTE for such copolymer structures are obtained. The greatest increase in Tg of 430 to 465 K was observed when reducing the radius of the nanoparticles from 8 to 3 nm at the mean expected value of 5 nm. This is true when chemical interaction between the epoxy resin and anhydride-modifier takes place. The magnitude of the CTE increases from 1.95×10-4 up to 2.05×10-4 by increasing mean radius of nanoparticles from 3 to 7 nm. Conclusions: The expression for the theoretical estimation of Tg value of nanocomposites was modified in order to account for the polydispersity of nanoparticles. The theoretical estimation shows that the influence of the size distribution of the silica nanoparticles on the both of Tg and CTE values of the epoxy/silica nanocomposite can be quite considerable. The most significant effect will be achieved at the conditions, when nanoparticles play the role of multifunctional curing agent.

The effect of nanotubes and nanofibres on the stress relaxation of nanocomposites based on high-density polyethylene (HDPE) was studied. It was found that a very low concentration of multiwall nanotubes (0.1 wt%) leads to a significant increase in the relaxing stresses over the entire period of relaxation. Generalised curves of the relaxation process were plotted, and it was found that the greatest reinforcing effect is rendered by the multiwall nanotubes with the greatest specific surface.

The abrasion of materials based on blends of ABS plastic with polyvinyl chloride (PVC) as well as terraced boards based on wood-polymer composites (DPC) has been studied. The measurements were carried out on a drum-type machine, and on a Taber's abrasimeter. For blends of ABS plastic with PVC at abrasion path length 600 m wear is 0.85%. For terracotta boards based on WPC, the wear during the test (loss of mass) was 0.0042 g. The abrasion of the sample was 9.29x10(-5) g/cm(2). Thus, the obtained blends should be recommended for application for floor coverings, since they possess negligible abrasion.

A calculation scheme has been developed for estimating the forced elasticity limit and viscosity of a system containing a polymer and a solvent (plasticiser). Allowance is made for the chemical structure of the polymer and solvent, the intermolecular interaction between the polymer and solvent, the van der Waals volume and the molecular weight of the repeating unit of the polymer and the solvent molecule, and the solvent concentration. The temperature dependences of viscosity are obtained. The calculation scheme has been computerised and forms a separate option in the ‘Kaskad’ computer program (INEOS).

Изучено влияние нанотрубок и нановолокон на релаксацию напряжения нанокомпозитов на основе полиэтилена низкого давления (ПЭНД). Найдено, что очень малая концентрация многостенных нанотрубок (0.1 мас. %) приводит к значительному повышению релаксирующих напряжений на всем протяжении процесса релаксации. Построены обобщенные кривые процесса релаксации и найдено, что наибольшим усиливающим эффектом обладают многостенные нанотрубки УНТ 1 , характеризующиеся наибольшей удельной поверхностью.

Calculation scheme is suggested for estimating the yield strength and viscosity of the system containing the polymer and solvent (plasticizer). The chemical structure both of the polymer and solvent, the intermolecular interaction between the polymer and solvent, the van der Waals volume and molecular weight of the repeating unit of the polymer and solvent molecules, the concentration of the solvent has been taken account. The temperature dependence of the viscosity is plotted. The design scheme is computerized and included as a separate option into computer programs Cascade (INEOS RAS).