Study of the microstructure of low-molecular rubbers

The oligomer microstructure, reflecting the configuration of the elementary units (cis-1,4-, trans-1,4-, and 1,2-) and their distribution order in the polymer chain, decisively affects the physicochemical and rheological properties of the oligomer. Parameters of microstructure-dependent transitions (glass transition) characterize the oligomer behavior under abnormal low-temperature conditions. We present the results of studying the microstructure of low-molecular rubbers. We determined the content of cis-1,4- and trans-1,4-structural links of poly-divinyl-isoprene-urethane-epoxy oligomer. The structure of polybutadiene HTPB-IV with terminal hydroxyl groups was analyzed using NMR and IR spectroscopy. A comparative analysis of the microstructure of the poly-divinyl-isoprene-urethane-epoxy oligomer and low molecular rubbers with a known content of structural units has been carried out. The obtained results can be used to obtain oligomers with the desired physicochemical and mechanical properties.

ANALYSIS OF THE INFLUENCE OF THE NATURE OF THE FILLER SURFACE ON THE PROPERTIES OF HYBRID ORGANIC-INORGANIC NANOCOMPOSITES BASED ON EPOXY OLIGOMER

The aim of this work was to investigate the influence of the chemical nature of the filler surface on the properties of hybrid organo-inorganic nanocomposites based on epoxy oligomer ED-20 in the presence of nanoscale functional filler of inorganic origin - aerosil, with different surface nature. The influence of the chemical nature of the surface of highly dispersed aerosil on the thermal properties of nanocomposites based on epoxy oligomer ED-20 has been studied. The peculiarities of the process of thermooxidative destruction have been studied. It is shown that the introduction of highly dispersed aerosil in the amount of 0.5% in the epoxy matrix does not lead to changes in the thermal properties of composites, and the nanofiller in the amount of 5% improves thermal stability of composites. The kinetics of the curing process of epoxy nanocomposites was studied by IR-spectroscopy. The influence of the presence of functional groups on the nanofiller surface on rate and the degree of conversion of epoxy groups was determined. The presence of hydroxyl groups on the surface of A-300 contributes to the rate of conversion of epoxy groups to a greater extent, compared with aerosil with a modified surface, which contains on the surface methyl groups capable of blocking reactive groups. It is established that the rate of conversion of epoxy groups in the presence of aerosil decreases in the range of ED-20 > ED-20 + A-300 > ED-20 + AM-300. The sorption properties of epoxy nanocomposites have been studied. It is established that the sorption process proceeds at a higher rate when the matrix is filled with unmodified aerosil. The mechanism of influence of the chemical nature of the filler surface and content on formation and properties of epoxy nanocomposites is discussed.

Modified Epoxy Resins for Perpreg Technology

A curing system has been developed for obtaining high-strength compositions matrix, which is used in the production of composites based on reinforced carbon fiber using prepreg technology with a curing temperature of . A technology has been developed for combining an epoxy oligomer with a curing agent and modifier. The pot life of the prepared prepregs is at least 15 days.

Evaluation of the Effect of Sizing Compositions on the Properties of Hydrated Cellulose Technical Yarn

The influence of sizing compositions on the reinforcing properties of hydrated cellulose technical yarns has been investigated. The optimal mode of modification of hydrated cellulose yarns has been determined. The evaluation of the structural properties of the modified yarns has been carried out. The kinetic features of the modified yarns wetting by an epoxy oligomer have been studied.

Development and optimization of fire-protective coating composition based on epoxypolymers

The object of research is intumescent fire retardant coatings based on epoxy resins. The research is aimed at the development of mathematical models of the dependence of the swelling rate of intumescent fire retardant coatings on their composition. Considering the complexity of the processes during the formation of a protective carbon layer, it is advisable to select the optimal ratio of the components of an intumescent fire retardant coating experimentally, followed by the construction of mathematical dependences of the swelling ratio on the coating composition. Therefore, experimental studies aimed at developing and optimizing the composition of an intumescent fire retardant coating based on epoxy polymers are an important task. The studies were carried out in accordance with the theory of planning experiments with the construction of an orthogonal compositional plan of the second order. A linear swelling factor was chosen as the response function. Compositions based on the ED-20 epoxy oligomer, cured with polyethylene polyamine and filled with ammonium polyphosphate, aluminum hydroxide, and graphite additive were used for the study. Based on the results of processing the experimental results, a regression equation was obtained and response surfaces were constructed that describe the dependence of the linear swelling coefficient Cs of an intumescent composition based on an epoxy oligomer on the content of ammonium polyphosphate, aluminum hydroxide and graphite additive. A complex relationship is shown between the content of components and the linear swelling coefficient Cs with different ratios of the components. The optimum by the linear swelling coefficient (Cs=68.1) content of the components in the epoxy polymer was determined, amounting to 20 wt. including for ammonium polyphosphate, 15 mass parts including for aluminum hydroxide and 3 mass parts for the graphite additive. However, with such a ratio, the «self-extinguishing» condition is not met (Cs=27 %). Filling the composition with ammonium polyphosphate in an amount of 26.3 mass parts including, aluminum hydroxide 25 mass parts and 3.5 mass parts including graphite additives allows to get an intumescent fire retardant coating with a swelling ratio Cs over 63 and a reduced level of flammability (Ci=31 %)

Optimization of Ingredients upon Development of the Protective Polymeric Composite Coatings for the River and Sea Transport

It is proved that in order to increase the operational characteristics of parts of the river and sea transport, including their physical and mechanical properties, it is advisable to use the protective polymeric composite coatings. The effect of fillers on the flexural stresses of the developed epoxy composite was analyzed. The critical content of components was determined by the method of mathematical planning of the experiment: the synthesized powder mixture - 0.05 pts.wt., discrete fibers - 0.10 to 0.15 pts.wt. per 100 pts.wt. of epoxy oligomer ED-20. Introduction of such ingredients into the epoxy binder allows to increase the flexural stresses to σ f=77.4…78.6 MPa. The obtained results allow to create materials with improved values of physical and mechanical properties.

The Study of the Influence of Chemical Nature of Functional Groups in Oligomeric and Low--Molecular Modifiers on the Rheological Properties of the Epoxy Oligomer

The influence of chemical nature of modifier functional groups on the level of intermolecular interactions in the system "epoxy oligomer ‒ modifier", as well as the structure formation and dynamic viscosity of epoxy oligomer has been studied in detail. Modifying additives in low concentrations contribute to an increase in the degree of structure formation of the epoxy system by increasing the intermolecular interaction between the associates of the epoxydiane oligomer. It was established that the strength of the formed coagulation structures depends both on the compatibility parameter of the modifiers and ED-20, and on their intermolecular interaction energy.