Polymer Science, Series B最新文献

Surface modification of Kosa silk was conducted to enhance its dye ability along with introduction of antimicrobial activity. The modification was achieved through graft copolymerization of two quaternary ammonium salts namely [2-(Methacryloxy)ethyl] trimethylammonium chloride (MAETC) and vinyl benzyl trimethyl ammonium chloride (VBT) using ceric ammonium nitrate (CAN) nitric acid redox combination. Effect of various experimental variables such as dye concentration, pH, contact time duration, and temperature were investigated. The grafted Kosa silk fabric was then subjected to exhaust dyeing with Acid Blue 25. The color properties of the dyed fabric were analyzed in terms of CIE L*, a*, and b* values (where L represents the difference in lightness/darkness, a denotes the difference in redness/greenness, and b refers to the difference in yellowness/blueness) and K/S values. The antimicrobial activity of the modified silk was evaluated using the Agar-Well Diffusion method against gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacterial strains.

The structural diversity of organosilicon compounds used in decorative and care cosmetic products is studied. The unique physicochemical properties of silicones allowing their application as emollients, moisturizers, emulsifiers, film formers, viscosity regulators, and antistatic and binding agents are described. Mechanisms of action of various structure silicones, due to which organosilicon compounds are advantageously used to impart certain properties to cosmetic products, are demonstrated. A comparative analysis of the efficiency of silicones versus natural compounds serving similar functions in cosmetic products is performed. The issue of silicone safety for human health is considered.

The paper presents the results of mechanical and electrical tests of composite materials based on biodegradable polymers (polyvinyl alcohol, polyacrylamide, starch) and synthetic layered double hydroxides (Ni–Al, Zn–Al) obtained by two-stage (chemical) and one-stage (plasma chemical) methods. The one-stage method for producing composites involves the formation of filler structures during the burning of low-temperature plasma in the bulk of an aqueous polymer solution. Electrode materials were used as precursors. Regardless of the production method, 2D hexagonal structures are formed and embedded in the polymer matrix. This is evidenced by IR spectroscopy data showing shifts in the main characteristic bands and the appearance of new ones. It has been established that layered fillers can be both plasticizers and reinforcing agents. The influence of the viscosity of the polymer matrix on the mechanical characteristics of the composites has been revealed. The introduction of fillers changes the surface roughness, leading to an increase in hydrophobicity of the composites. It has been established that the current–voltage curves of the composites are nonlinear, so that such composites can be considered as flexible analogues of nonlinear electronic components.

Ethyl acrylate and butyl acrylate were used as monomers, vinyl monochloride acetate was used as the crosslinker in vulcanization reactions and sodium dodecyl sulfate was used as the emulsifier to prepare a general-purpose acrylic rubber. The synthetic products were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry, and other methods. Then, the raw rubber, carbon black, vulcanizing agent, and so forth were mixed and then vulcanized, and the performance of the product was tested. The results showed that the synthesized acrylic rubber contained low levels of ash and volatile matter. The structure of the acrylic rubber was consistent with its design, and the glass transition temperature was –28.1°C. A study showed that the product vulcanized quickly. When the dosage of butyl acrylate was increased, the tensile strength decreased, and the elongation at break increased. The working temperature was reduced by adding plasticizer. With increasing plasticizer (RS-735) content, the elongation at break increased, and the tensile strength decreased. When the RS-735 level reached 10 phr, the brittleness temperature of the product decreased to –28°C. This product is resistant to oil and high temperatures, and it can be used widely in environments from –28 to 180°C.

The effect of introduction of polyamide nonwoven materials on the thermal and mechanical properties of polymer composite materials based on phthalonitriles and a carbon fabric is studied. It is shown that the addition of 3 wt % of polyamide nonwoven material causes a 44% increase in the specific work of delamination. At room temperature elastic mechanical characteristics, such as compressive strength and compressive modulus, for the composite modified with the nonwoven material increase by 12 and 100%, respectively. According to dynamic mechanical analysis, upon reaching 169°C the melting of polyamide occurs; however, there remains the possibility to use the composites above this temperature, as confirmed by mechanical tests performed at 200°C.

Carbon nanotubes (CNTs)/polyamide-6 (PA6) nanocomposites with different CNTs loadings have been prepared by in situ polymerization approach. Then the blends were extruded into fibers using melt spinning technology to prepare as-spun and drawn fibers. Scanning electron microscopy observation on the fracture surfaces of the composite’s fiber shows not only a uniform dispersion of CNTs but also a strong interfacial adhesion with the matrix. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results show that CNTs act as strong heterogeneous nucleating agents for PA6 crystals. The breaking strength of drawn composite fibers, with incorporating less than 4 wt % CNTs, is slightly higher than that of pure PA fibers prepared at the same draw ratio. The PA6/CNTs composite fibers reveal a high increase in breaking strength as the draw ratio increased. Due to the electric conductivity of CNTs, electrical resistivity of the PA6/CNTs composite fibers is reduced.

Inspired by mussel heuristic chemistry, a novel method for improving surface wettability and adhesion of carbon fibers with epoxy resins was proposed by codepositing gallic acid and polyethylene imine on the carbon fiber surfaces in a convenient operation. The results of scanning electron microscopy, infrared, Raman and X-ray photoelectron spectra revealed that gallic acid and polyethylene imine could undergo Michael addition or Schiff base reaction and codeposit on the carbon fiber surfaces successfully. The gallic acid-polyethylene imine codeposited carbon fibers were used to fabricate epoxy matrix composites. The results of mechanical tests showed that interlaminar shear strength, flexural modulus and strength of the gallic acid-polyethylene imine codeposited carbon fiber composite were increased by 27, 38, and 27% respectively, compared with those of the untreated carbon fiber composite. The conclusion can be drawn that the gallic acid-polyethylene imine codeposition is an effective method for improving interfacial properties of carbon fiber reinforced epoxy resin matrix composites.

Composite fibers containing boron(III) have been obtained based on solid solutions of cellulose in N-methylmorpholine-N-oxide and orthoboric acid with their subsequent transformation into a viscous-flow state. The rheological behavior of cellulose solutions with different content of orthoboric acid and water studied under conditions of continuous and dynamic shear loading has confirmed the intermolecular interaction between the components. It has been shown that the mechanical characteristics of the composite fibers obtained from a 16% solution in N-methylmorpholine-N-oxide are comparable to these for hydrated cellulose fibers. The process of transformation of the composite fibers of various compositions into carbon fiber has been investigated by means of thermogravimetric analysis and differential scanning calorimetry. Chemical, structural and morphological properties of composite hydrated cellulose fibers and carbon fibers obtained from them have been studied using FTIR-spectroscopy, X-ray diffraction, and scanning electron microscopy. The influence of boron(III) compounds on the carbonization process and the formation of graphite-like structures in carbon fiber has been investigated by Raman-spectroscopy.

The possibility of using organomineral complexes of polyhexamethylene guanidine hydrochloride as a functional additive for a waterborne paint based on polyvinyl acetate has been investigated. Organomineral complexes containing 20 and 30 wt % guanidine polymer have been obtained, with intercalation of polyguanidine chains into the interlayer space of montmorillonite being observed. It has been revealed that the stability of the polymer film to water is retained when organomineral complexes are introduced into a polyvinyl acetate dispersion, whereas the water resistance of the film sharply decreases when free polyguanidine is added. There was no significant influence of organomineral complexes on the rheological characteristics of the dispersion and its sedimentation stability. Testing of waterborne paints with various additives has shown that introduction of organomineral complexes into the material prevents the coating from fouling by biofilms of gram-positive bacteria Staphylococcus aureus and Rhodococcus erythropolis, with the hardness, water resistance, and water-vapor transmission of the coatings being retained at a satisfactory level.

Articular cartilage (AC) defects may be caused by injury or osteochondral pathology, which is a major risk factor for catastrophic degenerative arthritis. Currently, AC defects are a serious concern for patients because clinical treatments are not satisfactory. Owing to the limited self-healing ability of AC, the proliferation and chondrogenesis of seed cells are necessary for cartilage tissue regeneration. To treat AC defects, growth factors are required to regulate the behavior of seed cells for optimal therapeutic effects. Considering these issues, injectable hydrogels are suitable for both the repair and regeneration of AC because of their unique structural and functional features. After literature search and analysis, we introduced several gelation methods for injectable hydrogels. We then highlighted the biomedical applications of injectable hydrogels in the field of AC tissue engineering, with an emphasis on composite hydrogels, cell therapy, and carrier delivery. Finally, the achievements and challenges of injectable hydrogels for AC repair and regeneration were discussed based on previous studies. The summarized developments help to understand injectable hydrogels in the field of cartilage tissue engineering.