Polymer Science, Series A最新文献

Nanocomposites of low-density polyethylene (LDPE) with a nanocarbon nanofiller, reduced graphene oxide (RGO) of different composition, have been obtained under conditions of high-temperature shear deformations in a rotary disperser. Structure and properties of the obtained nanocomposites have been studied using a wide range of physico-chemical methods of analysis, including laser diffraction, scanning electron microscopy, and measurement of mechanical and electrical parameters. The influence of the components ratio in the compositions on the characteristics of the resulting materials has been demonstrated.

The carbazole compound (C-C₈) containing aromatic ring with 8 carbon alkyl group (C₈) was synthesized. The thiophene-derived compound that was abbreviated as (T) was synthesized, and (CT-C₈) was obtained by adding of (T) to the starting compound (C-C₈). Additionally, the electrochemical polymers of CT-C₈ were synthesized and accumulated onto different surface types such as an indium tin oxide (ITO) coated glass, aluminum (Al) layer, copper (Cu) sheet and pen tip electrode (PTE). The electrochemical syntheses of the polymers were performed by using 0.05 M NaClO₄ as an electrolyte in acetonitrile (AN) solvent. The electrochemical behaviors of the polymers were also investigated by taking the cyclic voltammeric measurements with a triple electrode system, and the electrochemical behaviors of the coated polymers on different electrode surfaces were also researched in the presence of Fe³⁺ and Fe²⁺ metals. According to the obtained voltammogram results, it can be said that the electrochemically synthesized polymers on different electrode surfaces were sensitive to Fe³⁺ metal and they could be used as an electrochemical sensor for all electrode surfaces as mentioned above. For the performed electrochemical measurements, the oxidation and reduction peak values obtained for different electrode surfaces were different from each other. When it is desired to examine the electrochemical property of a material, there is a need to search for more useful and economical insoles, since the conductive surface like ITO is deformed after repeated applications and expensive. This study, which offers an alternative conductive base to replace ITO, is important in this regard.

Branched polysaccharides have been isolated from basidiomycete raw materials of locally growing and cultivated Ganoderma lucidum. It has been found that the isolated fractions contain branched polysaccharides in the form of complexes with melanin. After purification of polysaccharides by ion exchange chromatography from locally growing and cultivated basidial raw materials, two fractions have been obtained: neutral polysaccharides of locally growing Ganoderma lucidum (GW-1), cultivated Ganoderma lucidum (GWL-1) with a yield of 25.71 and 29.85%, respectively, and anionic polysaccharides of locally growing Ganoderma lucidum (GW-2), cultivated Ganoderma lucidum (GWL-2), with a yield of 5.26 and 4.19%. The physicochemical properties of the obtained samples have been studied by IR and UV spectroscopies. The purity degree of fractions of branched polysaccharides has been determined. Using gas chromatography, one-dimensional (¹³C NMR, ¹H NMR), and two-dimensional (COSY, TOCSY, HSQC, HMBC, NOESY) NMR spectroscopies, the compositions and molecular structures of the obtained polysaccharide samples have been determined. The results showed that the isolated and purified polysaccharides are β-glucan-type branched polysaccharides that have branch point (1,4,6)- and (1,3,6)-linked glucopyranose residues.

The structure and rheological properties of aqueous solutions of the anionic surfactant potassium oleate and the water-soluble monomer acrylamide before and after radical polymerization have been studied. In the absence of monomer and in the presence of a low-molecular-weight salt, potassium oleate forms a network of long entangled cylindrical (wormlike) micelles. The addition of the monomer does not lead to a change in their cylindrical shape and radius, but it promotes the transformation of branched micelles into linear ones. The structure of surfactant aggregates changes significantly after polymerization: according to neutron scattering data, it becomes bicontinuous and its local geometry becomes lamellar. The coexistence of such a structure with polyacrylamide macromolecules in a semidilute solution leads to a significant synergistic increase in viscosity and elastic modulus.

The idea of sustainable and circular utilization of difficult to decompose plastics is pursued to add value to other products. New epoxy mortars suitable for construction repair made from epoxy oligomer, amine and modified PET waste hardeners mixed with sand were prepared. Three types of carboxyl terminated PET (CTPET) were used as co-hardeners, along with an amine, to prepare new combination linkage epoxy mortars. Investigation of the viscoelastic properties revealed that the CTPETs influenced the storage modulus at glassy state and the rubbery plateau, indicative of interfacial adhesion between the epoxy matrix and sand aggregates. Additionally, the damping behavior and glassy temperature were increased with the addition of CTPET. Moreover, the combination linkage of ester groups from the CTPET likely contribute to the enhancement of compressive strength and flexural strength in the epoxy mortar. The results of absorption and flexural change after immersion in solution, as well as the interfacial flexural bonding strength with ordinary cement-based material were also investigated.

A series of water-soluble comb-like copolymers of N-methyl-N-vinylacetamide and N-methyl-N-vinylamine (MVAA‒со‒MVA) bearing hydrophobic dodecyl side groups С₁₂Н₂₅ has been investigated by means of molecular hydrodynamics (viscometry, translational diffusion, and analytical ultracentrifugation) in dilute solutions in 0.1 M NaCl, under conditions of suppression of the polyelectrolyte effects. The issues of homology of these amphiphilic copolymers have been considered. The viscometry data plotted as lnη_r as function of c[η] have allowed to distinguish between macromolecules of the copolymers according to their hydrophobicity. Positive values of the second derivative B₂ determined from the initial parts of these curves have served as a measure of hydrophobicity of the amphiphilic copolymers. The noticeable differences in the B₂ values for different copolymers have shown that they do not form true homologous series. For the quasi-homologous series of the MVAA–со–MVAC₁₂H₂₅·HI copolymers with close values of B₂, the Kuhn–Mark–Houwink–Sakurada relationships have been obtained and the equilibrium rigidity of the chains has been assessed using the modified Gray–Bloomfield–Hearst equation.

Different materials are being tested to get high energy and power density to develop highly efficient energy storage devices to bridge the gap between the battery and capacitor. In this regard, supercapacitors have become a potential solution due to their remarkable electrochemical capabilities, wide working-temperature range, cost-effectiveness, safety, and better cyclic stability. This review provides a concise overview of the structural characteristics, surface chemistry, synthesis methods, and potential applications in energy storage of conducting polymers (CPs) and transition metal dichalcogenides (TMDs) in the context of supercapacitors. Additionally, this paper provides a detailed discussion of various synthesis methodologies that are suitable for the design of composite-based energy storage devices using CPs/TMDs. Moreover, the primary focus of this review elucidated the utilization of CPs/TMDs composite as an electrode in devices, providing a comprehensive understanding of the charge storage mechanisms, stability, and compatibility with electrolyte solutions. In conclusion, it is of utmost significance to note that the future outlook presents a comprehensive perspective and novel pathway for future research endeavors aimed at utilizing this group of materials in the field of energy storage applications. The composite of conducting polymers (CPs) and transition metal dichalcogenides (TMDs) is highly advantageous for energy applications due to its exceptional characteristics, including fast charge and discharge rates, high power density, and extended lifespan.

This study analyzed and evaluated the mechanical properties of the Poly(butylene terephthalate) (PBT)/Polyamide 6 (PA6) mixture and the effect of glass fiber (GF) when mixed with PBT/PA6 mixture. Some potential applications are recycling PBT and PA6 into insulation or fire-retardant materials by mixing with an appropriate amount of fiberglass (GF). PBT/PA6/GF mixtures are prepared by injection molding method with 0, 3, and 6% GF in each PBT/PA6 mixture in 25/75, 50/50, and 75/25 respectively. After the injection molding, the samples are tested for tensile strength according to ASTM D638. The average tensile strength of PBT/PA6 at 25/75, 50/50, 75/25, and 100% PBT is 48.58, 42.52, 34.91, and 52.21 MPa. It shows that the tensile strength of the PBT/PA6 mixture decreases as the PBT content increases. The average elongation of the samples had a considerable deviation, with 25%PBT/75%PA6 reaching the maximum value of 37.92% and the 75%PBT/25%PA6 sample getting a nominal value of 0.94%. Besides, when mixing GF fiberglass into a PBT/PA6 blend with a 0 and 3% GF ratio, the tensile strength changes and decreases instability. But at 6% GF, there is a clear improvement as tensile strength gradually increases at all PBT/PA6 ratios. Therefore, to obtain an excellent tensile strength value, the GF content in the mixture should be more significant than 6% by weight of the blend. The elongation of PBT/PA6/GF samples is stable when the highest deviation is slight between the ratios. This research aims to serve as a reference for developing a method of mixing materials to produce the desired mechanical properties.

A laboratory procedure has been suggested for determining the concentration of carboxyl groups at the surface of polystyrene microspheres at the latex concentration of a few hundredths of weight percentage (the COOH groups concentration below 4 × 10⁻⁴ mol/L). The procedure is based on conductometric and potentiometric titration. The influence of polymer particles concentration in the system, ionic strength of the solution, titration duration, and the system inertness on the obtained values of the carboxyl groups concentration and the determination accuracy have been investigated.

The effect of vulcanization system on the properties of polymer-elastomer composite materials based on nitrile-butadiene rubber and ultrahigh molecular weight polyethylene is studied. An analysis of the rheometric and vulcanization characteristics of rubber compounds shows that, in the case of combined sulfur-peroxide vulcanization system, the crosslinking density of vulcanizates increases considerably. The study of the elastic and strength behavior and dynamic mechanical properties of the vulcanizates demonstrates that the sulfur-peroxide vulcanization system provides the best parameters, in particular at low temperatures. An examination of elastic and hysteresis properties of the samples before and after vulcanization, which are measured under dynamic loading in a wide frequency and strain range, allows one to describe the features of physicochemical interactions in polymer-elastomer materials depending on the used vulcanization system. The supramolecular structure of the vulcanizates is visualized by scanning electron microscopy, and chemical interaction between macromolecules of nitrile-butadiene rubber and ultrahigh molecular weight polyethylene occurring during peroxide vulcanization is proved by IR spectroscopy.