Polymer Science, Series D最新文献

The article considers the main stages of production of organomineral cellulose composite materials (CCMs) for information purposes—office paper. It shows the possibility of transition to resource-saving adaptation technology by forming paper from a mixture of partially bleached cellulose, bleached chemothermomechanical pulp (BCTMP) and mineral filler—precipitated calcium carbonate (PCC)—with the creation of a new type of office paper, ECO paper. The change in the nature of interfibrillar and interfiber bonds during the transition from bleached cellulose to partially bleached is analyzed. The morphological features of these semifinished products, as well as the optical and physicomechanical properties of the obtained paper are studied. The problems of directed change of the ζ potential of paper pulp during change of the nature of paper-forming fibers are outlined. On an industrial paper-making machine (PMM) with a capacity of more than 1000 t/day, pilot production was carried out and the PMM was transferred to serial production of new types of paper with the corresponding addition of current standards.

This paper is devoted to the issues of developing the methods for analyzing the performance characteristics of abrasive cutoff wheels and the derivation of dimensionless coefficients estimating their potential efficiency. The basis of the study in this paper is full-scale experiment on the cutting of a material with an abrasive cutoff wheel and the method of its ultrajet diagnosis. In the first case, the cutting force component is calculated to reveal its dependence on the quantity of abrasive grains on the surface of a contact between a workpiece and a wheel. The effect of an individual abrasive grain on the cutting-process efficiency is analyzed. In the second case, the dependence of the material removal rate under operation with an abrasive cutoff wheel and the wear resistance of its material under a diagnostic ultrajet is analyzed. It has been concluded that the results of a full-scale experiment with their informative parameters have a high (more than 0.9) correlation with corresponding ultrajet diagnostics parameters. The direct and indirect methods proposed in this paper for estimating the cutting properties of abrasive cutoff wheels can be used when selecting a supplier or for selective quality evaluation of a received lot of tools.

Processes of obtaining oligomeric melamine formaldehyde and urea-melamine formaldehyde materials for use as superplasticizers are considered. It is shown that the reactions occur in alkaline and slightly acidic environments at pH 4–7. The mechanism of action of superplasticizing additives in the technology of manufacturing structural concrete is presented. Results of testing the properties of cement mortars depending on the concentration of synthesized superplasticizers are presented. It is determined that sulfonated melamine formaldehyde resin has the greatest efficiency as a superplasticizer.

Promising components of surgical adhesives and sealants have been synthesized by radical polymerization of oligo(ethylene glycol) methacrylates—amphiphilic polymethacrylic molecular brushes containing oligoethylene glycol, oligopropylene glycol, or higher n-alkyl blocks in the side chains. The effect of the composition of such polymers on their resistance to ultrasonic destruction in aqueous and toluene solutions has been determined.

The formation of hydrophobic coatings under conditions of modification of glass and glass fabric by the product of hydrolytic condensation of triethoxy(octyl)silane is investigated. The influence of alkaline activation of glass and glass fabric, as well as intermediate removal of covalently nonimmobilized organosilicon modifier on the hydrophobicity of the obtained materials is considered. The obtained results are discussed within the framework of the Owens, Wendt, Rabel, and Kaelble models, as well as the Van Ouss and Good models, taking into account the components of free surface energy.

Data available from the literature concerning the use of cereal (wheat and rice) straw as a sorption material for eliminating hydrocarbon spills from water surfaces are summarized. Brief information on the composition of straw and on the amounts of its formation is presented. It is shown that cereal straw is a common, multitonnage, rather efficient, and cheap sorption material for removing oil and the products of its processing from water surfaces. It is shown that the sorption characteristics of straw with respect to oil and the products of its processing can be improved through straw modification with the use of various chemical reagents and physicochemical methods.

Comparative analysis is performed for the strength characteristics of high-pressure hoses without damage and with a restored defect in the form of a through notch. To restore damage in high-pressure hoses, it is proposed to use bandages from polymer composite materials based on carbon fibers and an epoxy binder. It is shown that the use of high-pressure hoses restored with a polymer bandage in the hydraulic lines of road-building machines makes it possible to preserve the performance characteristics of this rubber element.

The results of studies concerning the climatic resistance of ultra-high-molecular-weight polyethylene (UHMWPE) and a composite based on this substance are presented. Based on the conducted physicomechanical and structural studies, it has been found that UHMWPE and its composite are subject to photoinduced aging when exposed to sunlight under the conditions of Grade cold climate. It has been found that photooxidative degradation processes occur on the surface and in the subsurface layers of the composite up to a depth of 380 μm and do not affect the bulk of the polymeric matrix.

The work provides a comparative assessment of the behavior of experimental samples of polydioxanone (PDO) suture materials from two manufacturers during exposure to a model environment (in vitro) and in an experiment on laboratory animals (in vivo). The methods of DSC calorimetry, IR spectroscopy, scanning electron microscopy, and histological and physicomechanical studies have shown that even a minor violation of temperature and humidity conditions during production can lead to a violation of the physicomechanical properties of the medical device, which is unacceptable. At the same time, the patterns of transformation of the polymer structure in vivo and in vitro of the two manufacturers coincide: recrystallization of the supramolecular structure at body temperature takes place, and destruction of macromolecules occurs due to the “splitting” of the carbonyl and ether groups of the ester group.

Results of studies of the strength and elasticity moduli of basalt plastics during their tests for tension, bending, compression, interlayer shear, and crack resistance depending on the technology of their manufacture are presented. Three molding technologies were used in the work: vacuum infusion, impregnation under pressure, and contact molding technology from prepreg. It was experimentally found that the highest values (of the studied mechanical characteristics) are achieved when manufacturing samples using RTM technology, and the lowest when using vacuum infusion.