Polymer Science, Series A最新文献

The study exlores the possibility of using organomineral complexes, obtained as a result of adsorption of the macromolecular biocides (polyguanidines) on the montmorillonite surface, to protect composites based on plasticized polyvinyl chloride from photooxidative degradation and biofouling. According to UV spectro-scopy data and the results of measurements of the intrinsic viscosity of polymer solutions, it has been found that the introduction of organomineral complexes into the material helps to reduce the extent of photooxidative degradation of the material under conditions of hard UV irradiation. The organomineral complexes used effectively suppress the fouling of the composites by biofilms of the micromycete Yarrowia lipolytica 367-3. The mechanical characteristics of composites containing organomineral additives are maintained at a high level after thermal aging (in accordance with the technical documentation for the material). The composites also meet the technical documentation requirements for weight loss on heating, density, and volume resistivity, but increasing the concentration of the organomineral additive in the composite above 2 wt % leads to an increase in water absorption of the material above required values.

The current work presents the fabrication of polyaniline (PAni)/polyvinyl alcohol (PVA) nanofiber composites through electrospinning. The morphological properties of the sample evaluated by employing the field emission scanning electron microscope (FESEM) and the diameters of the samples are between 141 to 234 nm. The presence of both PVA and PAni in the nanofiber structure was evaluated with the aid of Fourier-Transformation Infrared Spectroscopy (FTIR). When a rifampicin-doped PVA film and a rifampicin-doped nanofiber PAni/PVA film were irradiated with a continuous wave laser beam at a wavelength of 532 nm, diffraction ring patterns (DFRPs) were seen. The nonlinear refractive index (NLDX) ({{n}_{2}}), was determined from the number of observed rings. Large value obtained of the order of 212.48 × l0^–8 cm²/W for PAni/PVA nanofiber composites. The change in the nonlinear refractive index (Delta n), depends primarily on both the natural refractive index of the material and the NLDX, in which diffraction patterns play a major role in this change. In addition to that, the optical limiting) ({text{OPT}}) (qualities were investigated. Within a solid PAni/PVA host, the dye shows of some impressive optical limiting features. It has been discovered that the mechanism responsible for the limitation of optical sensitivity is mostly of a thermal nature.

The separation of peptides with sequences inverted from N-terminus to C-terminus has been experimentally and theoretically investigated. Although these sequences are composed of the same amino acid residues, their adsorption properties are different. Theoretical calculations in terms of the BioLCCC peptide separation model showed that a difference in the adsorption properties of these sequences is due to a difference in the spatial correlation of chain connectivity of amino acid residues and terminal groups during their interaction with the surface.

In order to clarify the influence of processing parameters on the structure and properties of biaxially oriented polyethylene terephthalate (BOPET) films, by preparing BOPET film using a biaxial stretching film production line, the structures were characterized by means of DSC, WAXD, SAXS and the mechanical, optical, and thermal shrinkage properties were analyzed to investigate the effects of heat-setting temperature on the structure and properties of BOPET films. The results showed that with the increase of heat-setting temperature, the tensile strength in the machine direction (MD) of BOPET film decreased, while the fracture elongation and elastic modulus in the transverse direction (TD) increased. In addition, the crystallinity and long period of BOPET films increased, haze increased, and the transmittance and glossiness showed little change. However, the thermal shrinkage rates in both MD and TD decreased.

The composite hydrogel sodium graft poly(acrylic acid-co-N-isopropylacrylamide)/bentonite (SA-g-P(AA-co-NIPAM/BENT) emerges as an effective adsorbent to remove methylene blue (MB) and methyl violet (MV) from aqueous solutions through adsorption. Compared with the sodium graft poly(acrylic acid-co-N-isopropylacrylamide) graft copolymer SA-g-P(AA-co-NIPAM), the growth rate in terms of adsorption capacities of MV and MB is 35.5% (from 310 to 420 mg/g) and 10.2% (from 293 to 323 mg/g), respectively, with an incorporation of 0.6 g of BENT. The adsorption of MB on SA-g-P(AA-co-NIPAM/BENT) is spontaneous while MV is nonspontaneous. In addition, adsorption of both dyes satisfies the Freundlich equation and the Pseudo second-order kinetic model.

Herein, the SiO₂ nanoparticles were applied to decrease the thermal conductivity of cellulose acetate (CA) nanofibers via electrospinning and the oxygen-enriched method. Hence, solutions of CA and CA/SiO₂ were made by acetone/dimethylacetamide (2 : 1) with oxygen enriching and Helium gas. The nanofiber’s morphology and chemical structures were studied by SEM and FTIR, respectively. Finally, the media’s thermal conductivities were calculated using the two-plate Togmeter device test method based on BS 4745:2005, and the media’s tensile strength features were evaluated under the ASTM D638-10 standard. According to SEM images, SiO₂ nanoparticles incredibly covered the whole surfaces of CA nanofibers in the CA/SiO₂ medium in a cloud shape. FTIR vibration spectrums confirmed the siloxane bands vibrated at 475/75 cm^–1 in the CA/SiO₂ mat. Moreover, the thermal conductivity of the CA and CA/SiO₂ sheets were 0.1 W/(m K) with 0.225 ± 0.005 mm thickness and 0.044 W/(m K) with 0.461 ± 2.88 mm thickness, respectively. Additionally, the CA medium had 0.5 ± 0.28 MPa tensile stress at 2.57 ± 1.25% tensile strain and the CA/SiO₂ membrane had 0.561 ± 0.057 MPa at 1.81 ± 0.939%. Hence, the CA/SiO₂ nanocomposite medium has a super low thermal conductivity with good mechanical properties. Therefore, the characterization of the thermal conductivity of cellulose Acetate/nano-SiO₂ electrospun nanofiber composites for energy-saving, using an Oxygen-enriched method was completely successful.

For the first time using the density functional method in the 6-311++G(2df, 2p) basis set in the M06-2X hybrid functional approximation the nonplanar (dimensional) structure of sulfonyl chloride groups in chlorosulfonated polyethylene has been revealed. It has been shown that their structural features have a direct influence on the concerted mechanism of thermal degradation accompanied by the formation of a carbon-centered macroradical ({text{R}}_{n}^{ bullet }) and a chlorine atom Cl^•. The participation of these radicals in the processes of crosslinking macromolecules in the single-step production of thermoplastic vulcanizates has been experimentally verified.

RAFT polymerization was applied for the synthesis of hydrophilic poly(N,N-dimethylaminoethyl methacrylate) and random copolymers of N,N-dimethylaminoethyl methacrylate, containing 5 or 10 mol % of hydrophobic monomers methyl acrylate, methyl methacrylate, or butyl acrylate. The influence of chemical nature of hydrophobic comonomer and the copolymer composition on physico-chemical properties of polymers and their ability to strengthen friable (bulk) materials like quartz sand, clay, or limestone was systematically studied. It is shown that synthesized copolymers have relatively low glass transition temperatures, form aggregatively stable molecular solutions in water in a wide range of pH values, and have a pronounced surface activity, while their dried films demonstrate water-repellent properties. It is found that amphiphilic copolymers with a small content of hydrophobic comonomer units are much more effective as stabilizers of soils (bulk materials) in terms of mechanical strength and durability than the original hydrophilic homopolymer.

Using polarization and scanning electron microscopy and water vapor sorption the structure and properties of film composite nanomaterials based on hydroxyethyl cellulose and carbon nanotubes obtained in the magnetic field and outside the field have been studied. The films are anisotropic, which is associated with the formation of a liquid-crystalline phase during solvent evaporation from solution. Application of the magnetic field leads to the orientation of macromolecules and carbon nanotubess in the films, facilitating compaction of the structure of films and reduction in their ability to sorb water vapor. The Gibbs energies of the interaction of hydroxyethyl cellulose/carbon nanotube films obtained in the magnetic field and outside the field with water are calculated. For the films obtained in the magnetic field the negative values of the Gibbs energies decrease, indicating worsening of their interaction with water. With the introduction of carbon nanotubes into hydroxyethyl cellulose this effect becomes more pronounced.