Sotsenko V. Development of the epoxy anti-fouling coatings for protecting transport vehicles

Fouling of metal structures and surfaces of transport equipment causes significant damage during the operation of vehicles. Therefore, one of the most widespread methods of protecting metal structures from fouling is the application of organic polymer coatings. The most common means for increasing resistance to fouling are paints based on epoxy binders. To prevent physical and chemical processes of fouling of transport surfaces, polymer binders are filled with a certain amount of organic and inorganic fillers, modifiers, and passivating compounds. At the same time, it is relevant and of considerable scientific interest to develop materials with high resistance to fouling that are environmentally friendly, in particular for the marine environment. The purpose of the dissertation is to establish the basic regularities of the influence of the content of the modifier and dispersed additives in the epoxy polymer on the activation of structure formation processes during the creation of epoxy composite protective coatings intended for inhibiting the process of biofouling of water transport parts. Scientific novelty of the work. 1. The theoretical principles of the formation of reactive plastic matrices were developed, which take into account the relationship between the critical content of the polyethylene polyamine hardener in the DER-331 epoxy oligomer, the polymerization temperature (T = 413±2 K) and the structure and properties of the polymer. This made it possible to increase the adhesion strength of functional coatings in 2.2 times. 2. It was found for the first time that the introduction of the phthalic anhydride modifier into the DER-331 epoxy binder at the content of q = 0.1...0.5 wt.% at a polymerization temperature of T = 393±2 K provides an increase in the physical and mechanical properties of the matrix by 1.1...1.3 times and it is substantiated that this is due to an increase in the density of the polymer structure due to an additional restriction of the mobility of its structural elements when crosslinking the material in the presence of C-O, C=O modifier bonds. 3. The course of physical and chemical processes of thermal destruction of modified composites was established by the method of thermogravimetric and differential thermal analysis, and an increase in the activation energy of thermal destruction by 1.4 times (compare to the polymer matrix), the initial temperature of mass loss increases, which indicates that chemical bonds are resistant to temperature. 4. For the first time, an optimal ratio of dispersed biocide additives (oxytetracycline – q = 1.5 wt% + nano Ag – q = 0.075 wt%) in the DER-331 epoxy binder (q = 100 wt%) was determined. This provides the formation of nanoheterogeneous structure of coatings and leads to a change in the cell membrane of biobacteria with its subsequent destruction due to the rate of release of silver ions from the polymer surface. It has been proven that the developed coating has an inhibitory effect on probiotic strains of Lactobacillus acidophilus, Bifidobacterium bifidum, Escherichia coli, due to decrease of CFU/ml of test strains in aggressive environments by 1.3-2.5 times. In the introduction, the problem of many branches of industry is presented - this is biological fouling of metal structures and surfaces of equipment of transport vehicles, which negatively affects the service life and increases the economic costs associated with their maintenance and repair. The first section presents a brief description of polymer materials, in particular: their structure, properties, advantages and disadvantages, fields of application. The peculiarities of the use of polymer composite materials in the operation of sea and river transport are considered. The issue of corrosion and fouling of mechanisms and parts of transport vehicles was considered. The results of the study of the effect of inhibitors and inhibitory pigments (phosphates, metal oxides, biocides) on environmental toxicity and prevention of biofouling, which directly affects the operational qualities of means of transport, are presented. The second section substantiates the choice of components for the formation of protective coatings designed to inhibit the process of biofouling of vehicle parts. The methods by which experimental studies were carried out are described, in particular: modern methods of studying the structure of composite materials (optical and electron microscopy, differential thermal and thermogravimetric analysis, gas chromatography). In addition, the conditions and features of the study are given: adhesive strength (ASTM D897-08), fracture stresses during the flexion (ASTM D 790-03), modulus of elasticity (ASTM D 790-03), impact strength (ASTM D 6110-18 ), heat resistance according to Martens (ISO 75-2), thermal coefficient of linear expansion (ISO 11359-2).