The purpose of this study was to obtain information on the influence of the size factor on the climatic aging of circular fiber plastics produced by pultrusion. The kinetics of moisture transfer was obtained in humidification and drying modes at 60 °C in samples of epoxy basalt fiber reinforcement bars: after 28 months of exposure in the extremely cold climate of Yakutsk and 30 months of exposure in the moderately warm climate of Gelendzhik. It was shown that the 2D Langmuir model adequately describes the kinetics. The diffusion coefficients in the reinforcement direction for bars with diameters of 6, 8, 10, 16 and 20 mm turned out to be significantly higher than in the radial direction. To clarify the aging mechanism of the bars and the tensile, compressive and bending strength, the coefficient of linear thermal expansion and the glass transition temperature of the epoxy matrix of the bars with a diameter of 6, 8 and 10 mm after 51 months of exposure in Yakutsk and 54 months of exposure in Gelendzhik were measured. It was shown that after climatic exposure, the deformability of the bars decreased with increasing diameter of the bar; the glass transition temperature increased more significantly in the bar with a smaller diameter. In 6 mm diameter bars, the compressive and bending strength limits decreased by 10–25 % due to the plasticizing effect of moisture. With the same depth of moisture penetration into the volume of the samples, its effect on the strength of thin bars was significant, and for thick bars, it was insignificant. An increase in the glass transition temperature by 6 °C, associated with the additional curing of the polymer matrix, occurred in the surface layer of the epoxy basalt fiber reinforcement bars and was revealed in bars with a smaller diameter.

Detailed analyses of the reasons for changes in the mechanical parameters of fiberglass exposed to different climatic zones have been made available in the literature; however, such detailed studies of basalt plastic do not yet exist. It is possible to make reasonable conclusions on the climatic resistance of reinforced plastics by monitoring the deformation–strength characteristics in combination with fractographic and DMA analyses of the solar- and shadow-exposed parts of the plastics; additionally, one can conduct analyses of the IR spectrum and the moisture sorbtion kinetics. As a starting point for the climatic aging of polymer composite materials, it is necessary to accept the time of exposure in which the maximum values of the elastic strength properties of polymeric materials are achieved. Based on the results of the DMA analysis, it was found that, unlike basalt-reinforced plastics (where the material is post-cured exclusively at the initial stage of the exposure), in glass-reinforced plastic, a process of destruction occurs. The formation of internal stresses in the material and their growth were determined through observing the duration of climatic exposure. The formation of closed porosity, depending on the duration of exposure, can be assessed using the values of the increase in the average moisture content. A set of experimental studies has established that glass-reinforced plastics are subject to greater destruction under the influence of a very cold climate than the basalt-reinforced plastic.

The article is a review that addresses the problem of insufficient scientific basis for predicting the durability of polymer composite materials (PCM) during long-term use. Special attention is given to the influence of ultraviolet (UV) radiation and mechanical loads on PCM degradation. The text presents research findings related to polymer degradation under UV radiation, the impact of UV exposure on the mechanical properties of carbon-fiber-reinforced polymer composites, and the mechanisms of yellowing in thin films of epoxy and vinyl ester resins.

Due to the increasing number of catastrophic floods around the world, creation of an effective system to protect against natural disasters became particularly relevant. The paper investigates introduction of the basalt fiber to reinforce the composite sheet piles. Influence of the reinforcing fiber interlacing type on the nature of plastics destruction was established. Results of the work prove that basalt plastic (BP) exhibits higher climatic resistance than the fiberglass plastic (FGP). After post-curing, strength characteristics relative to the second year were decreasing by 15% with BP and by 22% with FGP in extension, and the strength limit in bending was decreasing by 12% with BP and by 47% with FGP. It was experimentally shown that under a long-term stationary thermal and humidity effect of 23°C/68RH, diffusion was observed on the basalt and fiberglass plastics consisting of two stages. The first stage had a satisfactory statistical error and was adequately approximated by the Fick’s diffusion model and the relaxation model. The second stage had an unsatisfactory statistical error for approximation and was of the spasmodic nature, while the jump in FGP was the largest indicating that the FGP was more susceptible to destruction exposed to the influence of long-term temperature and humidity regime of 23○С/68 RH, than the BP.

This study involved the exposure of epoxy-coated basalt-plastic rebars, with diameters of 6 and 8 mm, to the open climate conditions of Yakutsk and Tiksi, located in the Arctic region of Russia. The exposure duration was 54 months. Basalt-plastic rebars were tested both untreated and after contamination with a set of neutral microorganisms resilient to cold climates, including spore-forming bacteria from the genus Bacillus, and mold fungi from the genera Aspergillus. Results showed that after 12, 24, and 54 months of exposure, the tensile strength and modulus of elasticity of untreated rebars increased by 5–14% due to the post-curing of the epoxy matrix. However, in biologically contaminated rebars, these indicators decreased on average by 11%. Bacterial cells and fungal mycelium, which penetrated surface irregularities of the rebars under open climate conditions, contributed to microcrack development, reducing the mechanical properties of the basalt-plastic rebars and causing additional moisture diffusion in the radial direction of the bars.

Influence of a very cold climate on properties of basalt and glass textolites made by an infusion method by successively laying a reinforcing material on a mold and impregnating with a three-component epoxy binder is studied. Full-scale climatic tests at an open proving ground during 2 years led to a decrease of ultimate tensile strength by 14% and an increase of ultimate bending strength by 18% for the basalt textolite, the increase of the ultimate tensile strength by 9% and the ultimate bending strength by 22% for the glass textolite. Conducted studies of changes of surface relief showed insignificant variations of average amplitude of inhomogeneities up to 0.4 μm for the basalt textolite and up to 4 μm for the glass textolite. The conducted studies of these materials demonstrated their resistance to the climatic influences in a region of the very cold climates, which is confirmed by a high level of preservation of their strength parameters.