Polymer Science, Series D最新文献

Metal oxide catalysts most often show low yields of the target product. This is due to a number of reasons, such as large sizes of particles and nonuniform coating of a carrier. This study addresses the possibility of obtaining a catalyst for quinoline synthesis reactions. The basis of the catalyst is a mineral carrier with Cu/CuO or Ni/NiO nanoparticles embedded into its pores.

The paper considers the development of production of paper–polymer materials as environmentally friendly substitutes for synthetic polymers. The prospects of using paper–polymer composites based on available natural cellulose-containing materials with many technical advantages, in particular, the presence of a natural paper base, have been discussed. The prospects of carrying out work on modifying the properties of paper and other cellulose derivatives in order to obtain specialized materials and products on their basis have been shown.

The paper considers aging of the VKU-39 aircraft-grade carbon plastic in the moderately warm climate of Gelendzhik and the humid tropics of Wanning (China). The second part of the article presents the investigation results on the physical properties of the carbon plastic in the initial state and after 1 and 3 years of climatic ageing. Analysis of changes in the surface relief, moisture content, moisture diffusion coefficient, glass transition temperature, and coefficient of linear thermal expansion establishes that in the tropical climate, the epoxy matrix of carbon plastic is destroyed, while a moderately warm climate promotes its additional curing. The moisture plasticizing effect is shown to be a cause for the decrease of the strength indicators at the temperature of 120°C.

The linear amplitude sweep method was used to study the influence of temperature, short-term and long-term thermo-oxidative aging, and modification on the resistance of PG58-28 bitumen to cyclic deformations in the range from +19 to –5°C. Active powder of discretely devulcanized rubber obtained by high-temperature shear-induced grinding of rubber from recycled tires was used as a modifier. The temperature ranges of fatigue failure of samples were determined, and it was shown that a decrease in the test temperature and aging lead to an increase in shear stress peak value τ_max and a decrease in the deformation’s corresponding value γ, while modification leads to a decrease in τ_max, an increase in γ, and an increase in the postpeak section length on the τ(γ) curve. The features of formation of a three-dimensional network in the modified binder were analyzed.

The effect of finely dispersed powders of natural zeolites and limestones on the formation of the pore structure of concretes based on a sulfur binder and limestone fragmenting screenings is found. The hydrophysical properties of the developed composites are studied, and the advantage of the use of fillers made of zeolites and limestones for obtaining stable sulfur binders and concretes based on them with a high set of technical properties is shown.

The paper presents the results of works on a study of surface hardening of flat samples made of an aluminum alloy and corrosion-resistant steel in a cyclic compression mode without accumulation of unilateral plastic deformation. Processes of fabrication of the samples, mechanical properties of the initial semifabricated products, and procedures for their hardening are described, and the results of fatigue tests are shown. Conditions of plastic introduction of punches are considered, and it is experimentally shown that hardening is carried out in a region of macroscopic elastic deformations. Possible mechanisms of hardening are analyzed, and it is shown that the main acting factor of the hardening process is fatigue hardening.

The influence of various resins on the adhesive strength of hot-curing adhesive chloroprene rubber compositions is studied. It was found that the highest adhesive properties characterize a sample in which pentaerythritol rosin ester was used as a tackiness modifier. The bond strength in this sample is 6.64 kN m^–1, which is 30% higher than for that in which pine rosin was used as a tackiness modifier. It is shown that there is an increase in bond strength from 3 to 60% in all samples after aging in air. It was found that the highest increase in bond strength is in the samples with dispraktol KS-BP and pentaerythritol ester of rosin and is 60 and 30%, respectively. It can be concluded that hot-curing adhesive chloroprene rubber composition in which pentaerythritol rosin ester is used as a tackiness modifier possesses the optimal set of operational characteristics.

Effect of a novel natural complex filler on the thermal aging of high-pressure polyethylene (HPPE) is studied. This filler is a byproduct of the oil shale industry. The stabilizing effect of the carbon-mineral filler (CMF) on the thermal oxidation of HPPE is revealed. Introduction of CMF into polyethylene inhibits worsening of the deformation–strength characteristics of the polymer. A synergistic effect is observed when the CMF and antioxidant Irganox 1010 are used together.

The article summarizes data from literary sources on the use of wheat and rice grain hulls as sorption materials for eliminating hydrocarbon spills from water surfaces. Brief information on the composition of the hulls and their formation volumes is provided. It is shown that grain crop hulls are a common, high-tonnage, effective, and cheap sorption material for removing oil and its by-products from water surfaces. It is shown that the sorption characteristics of these materials for oil and its by-products can be increased by modifying them with various chemical reagents and using physicochemical methods.

New amphiphilic betulin- and oligo(ethylene glycol)-containing polymethacrylate molecular brushes are synthesized by the radical homopolymerization of the first synthesized macromonomers, oligo(ethylene glycol)betulin methacrylates, as well as by the copolymerization of betulin methacrylate with oligo(ethylene glycol) methacrylates (in the second case, the reactivity ratios of the comonomers are determined). It is shown that differences in the architecture of homopolymer and copolymer molecular brushes (different arrangement of oligo(ethylene glycol) fragments in side chains) affect the behavior of the polymers in aqueous solutions.