Polymer Science, Series A最新文献

Water-soluble random copolymer of N-vinylformamide with sodium 4-styrenesulfonate is synthesized by free radical copolymerization. Copolymer fractions are studied by the methods of molecular hydrodynamics: viscometry, translational diffusion, and sedimentation velocity in dilute aqueous solutions. Molecular characteristics and scaling relations are obtained. Considerable differences in the conformational behavior of molecules of the copolymer and N-vinylformamide and sodium 4-styrenesulfonate homopolymers are discussed.

Viscoelastic properties of magnetoactive elastomers with spherical and plate-shaped filler have been studied. Four series of samples based on silicone elastomer and carbonyl iron microparticles have been prepared. A series of samples with a concentration of magnetic filler from 30 to 60 wt % which differed in the shape of filler particles (spherical and platelike) and in their distribution in the polymer matrix (isotropic and anisotropic). The magnetorheological properties of the obtained magnetoactive elastomers have been examined by dynamic mechanical analysis. Storage modulus values for samples of different compositions are in the range of 10–100 kPa. It has been shown that anisotropic materials are stiffer than the isotropic counterparts and demonstrate a higher magnetorheological effect: the increase in the elastic modulus of an anisotropic sample with the maximum filler content exceeds an order of magnitude in a magnetic field of 1 T. At the same filler concentrations, materials based on platelike iron are stiffer than those based on spherical iron. At low magnetic filler concentrations, the use of platelike iron makes it possible to achieve a higher magnetic response of the material; at high filler concentrations, the increase in the elastic modulus is greater for samples based on spherical particles. The anisotropic materials exhibit a more pronounced Payne effect.

New modifications of a polyampholyte sorbent based on carbamide (urea), formaldehyde, and aminoacetic acid, differing in the reagents ratio during the synthesis, have been prepared. It has been shown that the optimal synthesis temperature is 90°C. Thermal stability of the polyampholyte has been analyzed. Sorption properties of the polyampholyte towards d-element ions have been investigated. The effect of the synthesis temperature on specific volume and static exchange capacity of the polyampholyte has been considered. The influence of the medium pH on sorption of copper(II) ions with the polyampholyte has been evaluated. It has been found that the sorption degree by the considered sorbents is the highest at pH from 5.5 to 6.5. The polyampholyte prepared at the urea, formaldehyde, and aminoacetic acid ratio 2 : 5 : 0.7 has revealed the highest sorption capacity towards the d-element ions. The sorption rate has been maximum at the solution temperature of 20°C. The adsorption has been shown to follow the Freundlich equation.

The heat resistance of adhesive joints of SVM heterocyclic aramid fibers and cyanoacrylate glue has been studied based on the adhesion failure temperature in an adhesion cell formed by a loop tightened into a knot. For the first time, data on the heat resistance of adhesive joints of fibers with a polymer matrix under static load with constant shear stress have been obtained. Using the example of two types of glue, the influence of filler in the glue and fibers on the glass transition temperature of polycyanoacrylate and the heat resistance of the adhesive joint is shown. The activation energy of adhesion failure was calculated, and the dependence of the thermal stability of the adhesive joint on the shear stress was shown to be of the Arrhenius type.

The poly(glycidyl methacrylate) microsphere (PGMA microsphere) is one of the most useful colloidal particles due to its structural arrangement. It has an easy functionalization, dispersion, adsorption and swelling properties. The PGMA was effectively used as a precursor for the development of many novel and advanced materials with enhanced properties lead to diverse applications. For instance, the incorporation of nanoparticles in PGMA exhibited progressive properties. Nevertheless, homogeneous distribution of nanoparticles in polymers is not that much simple due to their tendency to get aggregate. Whereas, the homogeneous distribution of nanoparticles in the PGMA is quite easy due to its grafting ability. The design, development and characterization of PGMA based novel materials for improved properties and apply those materials for diverse problems has gained a great interest among the researchers from the past one decade. This review highlights the insights on different methods of preparation of PGMA based materials to attain the desired properties and provide useful information about the characteristic features of the PGMA microspheres. This review also useful to evaluate some of the key aspects for the development of PGMA based materials and endow with new possible ways and ideas to take up some innovative research.

Phase diagrams with UCST are constructed for systems poly(methyl methacrylate)–butanol, poly(vinyl acetate)–methanol, and poly(vinyl acetate)–2-propanol. The boundary curve of the PMMA–о-xylene system is unusual in shape, which is explained by the fact that polymer macromolecules form stereo complexes that appear during solution cooling. The thermodynamic interaction parameters χ of components and the values of χ_cr and critical concentration of the systems under study are calculated. With increasing temperature the value of χ decreases, which indicates that the interaction of components is improved under heating and agrees with the phase diagrams of the systems.

This work is aimed at the preparation of complexes of chitosan and hydrophobically modified (HM) chitosan with an anionic surfactant sodium dodecylbenzene sulfonate (SDBS), and at the study of the virucidal activity of the complexes and their components against SARS-CoV-2. It is shown that the introduction of a sufficient amount (4 mol%) of hydrophobic n-dodecyl side groups provides the activity of HM chitosan against SARS-CoV-2 at moderate concentrations, at which unmodified chitosan and chitosan containing a lower amount of hydrophobic groups do not show any activity. Complexes of HM chitosan with SDBS are prepared, which is proven by fluorescence spectroscopy and isothermal titration calorimetry. It is discovered that HM chitosan/SDBS complex is more active than the polymer without surfactant, and an increase of the amount of hydrophobic groups enhances the activity.

Using two samples of chitosan (D-glucan) with viscosity-average molecular mass 40 × 10³ and 200 × 10³ as the example, the influence of diastereomer form (L- and D-) of ascorbic acid on the energetics of formation, structure, and supramolecular ordering of hetero- (D‒L) and homochiral (D‒D) polymer–acid salt complexes has been studied. It has been found that heat effect during the interaction of chitosan with L-ascorbic acid in aqueous medium and degree of protonation of the (D‒L)-salts are lower in comparison with D-isomer of the acid. The homochiral (D‒D)-salts, in contrast to the heterochiral (D‒L)-salts, have exhibited lower amount of crystallization water, high degree of crystallinity, and denser supramolecular structure with high level of inter- and intramolecular contacts.

The purpose of this review is to acknowledge the alternative for petroleum or synthetic polymers with biobased polymers for 3D printing (3DP) and to summarize the research done to date with biocomposites using 3DP technique, to highlight successes and opportunities in this field. This review also provides the idea about different types of additive manufacturing (AM) techniques, advantages of AM over traditional manufacturing and natural and synthetic biopolymers used for 3DP. This review also gives a brief idea about difference between 3DP and 4D printing. Different publications about biobased 3D printed composites have been described. This study concludes that, biobased materials can be used as feedstock material for 3DP instead of petroleum based materials. This article is helpful to study about the different biobased materials, their composites, nanocomposites that have been utilized for 3DP and basically the mechanical properties of the biobased 3D printed composites were discussed.

The use of synthetic single used plastic packaging and mulching films has serious environmental effects due to their non-degradable waste causing pollution. To replace these synthetic materials, high-strength biodegradable polymer composites of Pectin, Luffa Fiber (agro-waste) and Glycerol are synthesized by the solvent casting technique using a universal solvent. The experimentation is carried out using a 3 × 3 factorial design and the tensile behavior (tensile strength and elongation) of composites is analyzed by response surface methodology (RSM). The tensile strength of pectin containing 10% glycerol is 11.48 MPa which is increased to 19.34 MPa by incorporation of 15% luffa fiber and this composition is optimized with desirability index method (simultaneously optimization) to achieve the best results for elongation at break (188.89%) as well. The interactions between constituents of composites are characterized by FTIR spectro-scopy and scanning electron microscopic study reveals a uniform distribution of fiber. The composites have sustained thermal stability as all composites are stable up to 260°C in an inert atmosphere under TGA study. The biodegradability of composite films was observed by soil burial method and found completely degradable in 75 days. The present composites of non-toxic components with high tensile properties, sustained thermal stability and complete biodegradability are suitable for green packaging applications.