Shock fracture mechanisms of different scales were investigated on epoxy composite materials reinforced with silicon carbide microparticles of different concentrations. It is shown that the high...

Coatings based on epoxy diane oligomer ED-20 are being developed as environmentally benign, foulingresistant marine coatings. Silver oxide and carbonate (mixture) was used as filler, the dispersion of which is 0.5 µm. It is proved that for the formation of composites with the improved physical and mechanical properties it is necessary to add Mechanical Mixture of Silver Carbonate and Oxide (MMSCO) in the amount of q = 0.050…0.250 pts. wt. into the epoxy diane oligomer ED-20 (100 pts. wt.). The obtained values of impact toughness of composites during the introduction of MMSCO into the binder increased by 2.5 times compared to the epoxy matrix. Moreover, the maximum capacity to resist impact loads, including fracture toughness, was demonstrated by the Composite Material (CM) with the filler content q = 0.050 pts. wt. Impact toughness of this CM is а = 18.53 kJ/m2. The developed materials and protective coatings based on them were used on the dry cargo ship Oles Honchar.

The effect of nano-fillers (carbon carbon nanotubes) on thermophysical properties of epoxy composites is investigated. The curve showing the dependence between the heat resistance of epoxy composite and the content of nanoparticles demonstrates the optimal content of carbon carbon nanotubes, indicating the improved performance characteristics of the material with the above content of carbon carbon nanotubes. To analyze the processes of structure formation and the behavior of composites under the influence of a thermal field, the thermal coefficient of linear expansion of materials is investigated. It is established that the thermal linear expansion coefficient of materials increases with an increase in temperature within different temperature areas under study. Additionally, the thermogravimetric (TGA) and differential thermal (DTA) analysis of the materials were conducted for the investigation of nanocomposites under elevated temperatures. The maximum values of endothermic and exothermic effects in composites depending on their filling are found.

The corrosion resistance and hydroabrasive resistance of the developed epoxy composite coatings are investigated in this paper. The analysis of the penetration index change after τ = 50–150 days of immersion in a water medium and 10% sulfuric acid solution is carried out. The optimal ratio of the modifier and nanodispersed (Si₃N₄, Al₂O₃, AlN, and TiN) and fibrous (viscose, polyamide, matka silk, rong, and cashmere) fillers in the epoxy binder is determined. It was allowed to slow down the process of electrochemical reaction on the metal surface. The penetration of aggressive media in such a coating during the time t = 150 days is 0.8–2.8%. It is 1.5–2 times lower than the similar indexes of the initial epoxy matrix. The rational combination of the fibrous filler (wool, acrylic PAN, and cashmere), modifier, and nanodispersed (Si₃N₄, AlF₃, IH, and ZrH) filler in the epoxy binder is found, which allows to provide optimum indexes of wear rate. The wear rate under the action of a hydroabrasive of such a coating is I = 0.20%, which is 4 times lower than the similar indexes of the initial epoxy matrix. The wear mechanism of such coatings is caused by the physical and mechanical processes of microcutting and plastic deformation of the surface layer of the material.

The effect of carbon black (CB) nanopowder on the electrical properties of polymer composite systems based on the epoxy resin is investigated using the method of impedance spectroscopy. It is established that the electrical and dielectric properties of the studied systems significantly depend on the nanofiller content. It is found that electrical conductivity and dielectric constant exhibit percolation behavior when the filler’s content increases. In this case, the electrical conductivity increases exponentially, indicating the formation of filler electrically conductive mesh inside the polymer matrix. A small jump in electrical conductivity when reaching the percolation threshold indicates the formation of indirect contacts between the particles. The value of the percolation threshold of conductivity is 8%. It is shown that the dielectric constant of epoxy nanosystems is almost unchanged in the frequency range of 10²–10⁵ Hz. It is related to the structural features of the filler particles, which ensure the existence of a minimal dielectric gradient between the matrix and the filler. It is found that the dielectric constant of the studied systems also shows percolation behavior. The obtained material based on the epoxy matrix is characterized by a high value of dielectric constant, which at a carbon black nanopowder content of 29% is 4680. This material is characterized by relative frequency invariance and a high value of dielectric constant, so it has great potential for practical application.

The physical and mechanical properties of matrix based on epoxy resin ED-20 were investigated by adding unsaturated polyester resin ENYDYNE H 68372 TAE at different concentrations. The contents of polyester resin in the epoxy one by changing its concentration in the range of q = 10–120 mas.fr. were analysed. It was experimentally determined that matrix is characterised with its maximal rates of physical and mechanical properties with q = 10 mas.fr. of polyester resin ENYDYNE H 68372 TAE per 100 mas.fr. of ED-20. The received material is marked by the following indexes of physical and mechanical properties: fracture stresses during the flexion – σ_fl = 56.2 MPa, the modulus of elasticity during the flexion –E = 4.2 GPa, impact toughness –W = 12.8 kJ/m². It was proved that indexes of modulus of elasticity and impact toughness during the flexion of developed composite are higher in 1.5–2 times, in comparison with the indexes of matrix which is based on the epoxy resin ED-20. The images of fracture of the composite materials were analysed through optical microscopy. It was determined that the results of investigation correlate with the obtained indexes of physical and mechanical properties, confirming their authenticity. The clearly defined heterogeneity of given polymers was not observed on the photos of fracture, which indirectly points on the compatibility of the ingredients of the binder, chosen for the study.