The restoration of the load-bearing capacity of RC beams through crack injection is one of the most efficient and practical methods for executing repairs in the field of civil engineering. In the article, following an analysis of crack injection methods in RC structures, an economically viable method for injecting RC beams is proposed. The core approach of the proposed crack injection method involves the process of introducing epoxy resin into the crack, which occurs by gravity flow (without specialized equipment and pressure).
Study of the dependence of the dynamic mechanical properties of polymers based on mixtures of epoxy resin with polysulphide rubber, depending on the conditions for combining the components (carrying out a preliminary thioetherification reaction or mechanical mixing), the rubber content and the curing modes has been carried out.
A monocarboxylic derivative of Epidian-6 with free epoxy and carboxylic end groups (MCDER) has been synthesized using Epidian-6 epoxy resin and sebacic acid. The structure of MCDER was confirmed by a spectral analysis. The thermal stability of MCDER has been established and the formation of cross-linked films based on epoxy-oligomeric mixtures consisting of Epidian-5, TGM-3 oligoesteracrylate, and polyethylene polyamine has been studied in its presence. By means of IR spectroscopy, the chemistry of the mixtures formation has been established.
On the basis of Epidian-6 epoxy resin and methacrylic acid a monomethacrylic derivative of Epidian-6 with free epoxy and methacrylic groups (MMADER) has been synthesized. The structure of MMADER was confirmed by IR spectroscopy. The thermal stability of MMADER has been established. The cross-linking of unfilled epoxy-oligomeric mixtures and mixtures filled with CaCO3 has been studied in the presence of MMADER.
The main physical-mechanical and thermophysical characteristics of composite materials based on epoxy resin ED-20 and peroxide resin ED-20P (modified with tert-butyl hydroperoxide ED-20 of a molecular weight 480) in the ratio of 30 mass parts of ED-20P to 70 mass parts of ED-20 and unsaturated oligoester TGM-3 were researched. Butyl methacrylate was used as the active diluent of epoxy-oligoester mixtures. The polyethylene polyamine was used as hardener in a steochemical ratio. For the comparison we studied compositions which did not contain ED-20P resin.
In the food industry and public catering establishments of Ukraine, a sufficiently large amount of oil is left, which was first used during the roasting and cooking of various food, such as vegetables and fish during canning, french fries, pancakes, pies and the like. At high temperatures during contact with the food and moisture contained in it, the processes of thermal decomposition, oxidation, polymerization and so on, the oil accumulates harmful to man substances such as aldehydes, acids, ketenes, polycyclic compounds, etc. In this case, the oil becomes unsuitable for further food use.
Physico-mechanical properties of the products based on filled epoxy-oligomeric mixtures composed of Epidian-5 epoxy resin, oligoesteracrylate TGM-3 and monoperoxide derivative of Epidian-6 epoxy resin (PO) have been investigated. CaCO3 was used as a filler and polyethylene polyamine was a curing agent. The effect of PO and CaCO3 on the gel-fraction content and physico-mechanical properties was examined. Using a scanning electron microscopy (SEM) the morphology of the samples has been studied.
The mechanism of diepoxide and adipic acid (AA) reaction in the presence of benzyltriethylammonium chloride and 1,4-diazobicyclo[2,2,2] octane has been proposed. The thermal stability of the oligoester obtained via chemical modification of the dioxydiphenylpropane diglycidyl ether with AA and epoxy-oligoesteric mixtures with its participation has been studied. The viscoelastic properties of films based on epoxy-oligoesteric mixtures containing Epidian-5 epoxy resin, TGM-3 oligoesteracrylate, AA modified Epidian-5 and polyethylpolyamine have been determined.
Viscoelastic properties of amine-cured epoxytitania composites were investigated. The composites were synthesized by the sol-gel method and analysis of their physico-mechanical properties indicated that higher TiO2 content causes the decrease in glass transition temperature of the composites. Non-linear change of crosslink density with a filler content was observed.
In order to improve the properties of epoxy resins they are modified by the various compounds, in particular oligoesters. Compositions based on ED-20 epoxy resin and unsaturated oligoesters are structured in the presence of polyethylene polyamine (PEPA). The oligoester acts as a plasticizer that is not chemically bounded to the molecules of spatially crosslinked structure. It leads to the deterioration of their physical, mechanical and chemical properties during the working process of film based on epoxy-oligoester compositions.