Polymer Science, Series D最新文献

The surface modification of fillers (metal hydroxides) with phosphorus–nitrogen-containing compounds is considered. The influence of modified aluminum and magnesium hydroxides on fire-protective and physicomechanical properties of plastisol (fire-protective efficiency, adhesive strength to fiberglass, and resistance to thermal-oxidative degradation) is assessed. The possibility of using modified aluminum and magnesium hydroxide as a fire-retardant additive is described.

The ecological situation and rational consumption of natural resources require a responsible approach to the use of polymers and secondary polymer raw materials. In this work, polyethylene–polylactide blends with the addition of thermally aged polyethylene, the analog of secondary polyethylene, in the amount of 10, 20, and 30 wt % and 5 wt % wood flour were prepared. Using the method of differential scanning calorimetry, it was shown that with an increase in the secondary polyolefin content the melting temperature of polyethylene in the blends decreased by 2–4°C in comparison with the initial value and the degree of crystallinity decreased by 4–7%. The thermophysical characteristics of polylactide changed insignificantly. After incubation in soil for 120 days, the morphology and structure of the blends were studied by optical microscopy, differential scanning calorimetry, and IR spectroscopy. The morphology of the samples changed, and microcracks, dark spots, and erosions were formed on the surface. The weight loss during the experiment was higher for the sample containing 30 wt % of aged polyethylene.

Pine needles are mainly used to obtain extractive substances. In this case, after extraction, a postextraction residue is formed, which has a narrow range of application and, accordingly, disposal problems. The aim of the work is the extraction of pine needles with various solvents, fast pyrolysis of the postextraction residue of wood greenery with determination of the material balance and process parameters of the pyrolysis and study of the composition of the obtained pyrolysis liquid.

Research works on the development of urethane-forming compositions and carbon- and glass-fiber-reinforced plastics based on them obtained by vacuum infusion are continued. A laboratory thermovacuum infusion unit is created. Prototype samples of such composites are obtained and tested. Correlations between the qualitative indicators (viscosity, hydroxyl number (HN)) of component A in polyurethane (PU) binders and between the HN and physical and mechanical indicators of cured binders are found. It is shown that the dependences of the strength and Young modulus of PU films increase with increasing values of the HN and have an exponential and polynomial character of the dependence. An attempt is made to find explanations for the observed phenomena. It is found that the same regularities are observed on the composites as on PU films: the physical and mechanical indicators of carbon- and glass-fiber-reinforced plastics increase with an increase in the values of the HN.

Currently, the modernization of woodworking industries to glue wood veneer of various species is taking place in parallel with the development and implementation of low-toxicity adhesive materials and the improvement of technological process to provide the shortest duration of thermal gluing. The development of low-toxicity adhesive materials is to modify and to fill synthetic resins. Adhesive compositions with various active fillers are assessed. Positive results were obtained from tests on strength and toxicity of coniferous and deciduous plywood glued with adhesive compositions that have high physical and mechanical properties and low formaldehyde emission.

Literature data regarding the use of fruit shells of barley, buckwheat, and oat grains as sorption materials for liquidation of hydrocarbon spills from the water surface are summarized. Brief information is provided on the composition of fruit shells and volumes of their formation. It has been shown that the fruit shells of cereal crops are common, multitonnage, effective, and cheap sorption materials for the removal of oil and petroleum products from the water surface. It has been revealed that the sorption characteristics of these materials for oil and petroleum products can be increased by modification with various chemical reagents and physicochemical methods.

Compositions of aqueous functionalized hydroxyl-containing styrene–acrylic copolymers are developed. Selection of hardeners and conditions for the formation of hybrid polyurethane–acrylic thermosetting coatings with the optimum operational properties is executed. Great attention is paid to the selection of the functionality of the hydroxyl-containing copolymer, as well as ratio of the functional groups of the film-forming agent and hardener during the formation of the coatings. The degree of cure of coatings made of aqueous polymer dispersions is assessed by the concentration of a gel fraction in the samples after extraction, as well as indirectly by the hardness and water absorption of the coatings. It is found that the degree of cross linking of the copolymer expectedly increases from 53 to 88% with the increase in the concentration of OH groups in the copolymer from 1 to 10 mol % and at an equimolar ratio of the functional groups of the hardener and film-forming agent. The highest values of hardness of the coatings and minimum water absorption are observed at a concentration of the functional monomer in the composition of the copolymer in the amount of 3 mol %. Here, the molar ratio of the film-forming agent and hardener by the functional groups should be in a range of 1 : 1.00 to 1 : 1.15. At higher concentrations of the functional monomer in the composition of the copolymer, the lifetime of two-component compositions drastically decreases, and defective less uniform coatings are obtained.

The paper presents the kinetic data on the curing of an epoxy oligomer with an amine curing agent in terms of dielectric constant in comparison with shrinkage processes and residual stresses build-up. It was shown that the kinetic data on the curing of the ED-20 + TETA system obtained by different methods (dielectric constant, shrinkage, and residual stresses) allow one to evaluate the course of chemical reaction only in the kinetic region and practically do not cover the diffusion region. It was found that the kinetic data obtained for the curing of the ED-20 + TETA system in terms of dielectric constant and volume shrinkage correlate well with each other. The time lag of residual stresses build-up compared to dielectric constant and volume shrinkage indicates the coupling of these processes and their relaxation nature. To reduce the level of residual stresses in the diffusion region (from 11 to 22 h) in the technological curing process of the ED-20 + TETA system it is necessary to use heat treatment with temperature rise up to 80–100°C, increasing the rate of relaxation processes with almost constant volume shrinkage.

The influence of methods for postprocessing of products manufactured by FDM 3D printing from ABS and PETg+GF12 (GFmax) plastic on resistance to aggressive environments was studied. Recommendations for choosing postprocessing methods depending on the operating conditions of the products are given. Defects that arise during postprocessing are considered.

It is possible to significantly increase the strength and fire-resistant properties of wood via its impregnation with fire retardants. The impregnation of wood with fire retardants is used widely, but there are only a few industrial technologies applied mainly to produce machine-building parts, masts, sleepers, etc. Fire-retarded wood to obtain joinery and construction products and glued structures is of greatest interest, because the demand for fire-protective materials and products is constantly increasing. An FA-3 fire retardant based on oxyethylidenediphosphonic acid and monoethanolamine is proposed to produce fire-resistant wood materials (glued). When monoethanolamine interacts with oxyethylidenediphosphonic acid, a reaction product is a water-soluble crystalline triple amine salt. The advantage of the proposed fire retardant is that it is a member of the class of foam-forming fire-retardant compositions. Low-molecular gaseous substances are formed under high-temperature conditions, and this process leads to intensive foaming and the formation of a fire-protective layer that prevents the effects of open fire and thermal radiation on the upper layers of wood. The developed fire-protective composition provides to use industrially available components, which opens up wide opportunities for its implementation.