In order to improve the adhesive and physical-mechanical properties of epoxy-thiocol compositions cured without heat treatment, we propose to carry out the reaction of interaction between thiokol mercaptan groups and oxirane cycles of epoxy resin at an elevated temperature before introducing a curing agent, and then use the product of this thioetherification reaction for curing at room temperature. The temperature range of the thioetherification reaction (90–1800С) was determined by the method of differential scanning calorimetry. The optimal temperature (1600С) and duration of the preliminary thioetherification reaction (2 hours) were determined, which ensure the maximum level of adhesive strength and physical-mechanical properties. It was shown that composite materials based on the products of the thioetherification reaction significantly outperform analogs based on mechanical mixtures of epoxy resin and thiokol in terms of cohesive and adhesive strength, deformation capacity, fracture work and specific impact strength. The impact resistance and shear strength of adhesive joints are especially significantly increased during the curing of the compositions without external heat supply.

Harbin Institute of Technology, 92 Xidazhi street, Nangang District, Harbin, Heilongjiang Province, People's Republic of China

A tin-bromine-containing resin was prepared by the interaction of industrial ED-16 epoxy resin with dibutyltin dibromide. A comparative study of the physical, mechanical and relaxation properties of composites based on the original and modified resins cured at different temperatures has been carried out. It has been shown that the composite materials based on a modified resin are characterized by lower values of tensile strength, elastic modulus, fracture work and glass transition temperature as compared with the samples based on the original epoxy resin. The effect of water on the deformation and strength properties of composites was studied. A complex mechanism of the influence of moisture sorbed by the polymer on the complex of properties has been established, which may result from the imposition of the effects of plasticization and additional curing of the epoxy matrix. At short exposure times, the effect of the sorbed liquid is mainly aimed at weakening the intermolecular interaction in the sample, as a result of which its tensile strength decreases and its deformation capacity increases. At long exposure times, post-curing processes prevail, leading to an increase in the crosslinking density and, as a consequence, to a decrease in deformation capacity and an increase in the strength index. It has been shown that epoxy composites containing resin modified with dibutyltin dibromide are characterized by increased fungitoxicity and fire resistance. The studied polymers can be considered as promising for the production of antifouling coatings for hydraulic equipment on their basis.

Визначено можливості регулювання деформаційно-міцнісних, адгезійних та динамічних механічних властивостей епоксидно-полісульфідних композитів на основі продуктів попередньої реакції тіоетерифікації (ПРТЕ) за допомогою малих добавок поліоксипропілентріаміну та зміною вмісту оксиранових циклів в епоксидній смолі. Встановлено, що введення поліоксипропілентріаміну в композиції на основі продуктів попередньої реакції тіоетерифікації епоксидної смоли з рідким полісульфідним каучуком (тіоколом) приводить до збільшення адгезійної і когезійної міцності, деформації при розриві і роботи руйнування матеріалу. Ефект досягається як додаванням поліоксипропілентріаміну в суміш епоксидної смоли з рідким тіоколом в процесі проведення ПРТЕ, так і за його використання в якості співотверджувача. Показано, що присутність поліоксипропілентріаміну в продукті ПРТЕ значно впливає на динамічні механічні характеристики отвердженої композиції. Введення поліоксипропілентриаміну сприяє помітному збільшенню динамічного модуля пружності в області склоподібного стану композиту і молекулярної маси ділянки ланцюга між вузлами хімічної сітки, а також максимального значення тангенса кута механічних втрат і модуля втрат. Виявлено екстремальну залежність адгезійної міцності при зсуві клейових з'єднань, виконаних з використанням продуктів ПРТЕ, від вмісту епоксидних груп в смолі. Ефект зміцнення клейових з'єднань за рахунок модифікації полісульфідним каучуком найбільшою мірою проявляється для епоксидних смол, у яких вміст оксиранових циклів становить від 8 до 15 %.

A method for the synthesis of a complex based on an organic tin halide – dibutylol dibromide – and a aminophenol hardener of the UP-583 brand has been developed. It is found that samples cured with a complex hardener at room temperature are characterized by lower values of tensile strength, elastic modulus and glass transition temperature compared to samples cured with the original hardener UP-583. The values of strain at break are approximately the same for both hardeners. After heat treatment, the strength and modulus values for samples containing the complex sharply increase, as a result of which they are superior to samples based on UP-583. The deformation capacity does not change much, the glass transition temperature increases after heating, but remains significantly lower than for samples cured with the original UP-583. The observed change in the deformation and strength properties of samples during their exposure in a liquid medium is explained by the superposition of the effects of plasticization and re-hardening of epoxy polymers. At low exposure times, the action of the sorbed moisture is mainly aimed at weakening the intermolecular interaction in the sample. In result, its strength decreases and deformability increases. At large values of exposure times, when the amount of sorbed water becomes sufficiently large and a fairly intense molecular mobility develops, pre-hardening processes prevail, leading to an increase in the cross-linking density and, to a decrease in the deformation ability and an increase in the strength index. It is shown that epoxy composites containing a complex hardener are characterized by good performance in the water environment, increased resistance to the development of fungi and mold, as well as better fire resistance. The studied polymers are promising for obtaining antifouling coatings based on them for hydraulic equipment, sea and river vessels.