Polymer Science, Series B最新文献

This study focused on thermosetting high-ortho phenolic epoxy fibers prepared by blending thermosetting high-ortho phenolic resins (HOT-PRs) with F-704 epoxy resins and using dry spinning, thermal curing, and microwave curing methods. The structure was characterized by infrared spectroscopy, microinfrared spectroscopy, nuclear magnetic resonance spectroscopy, and scanning electron microscopy. The heat resistance of different fibers was studied by thermogravimetric analysis, and the mechanical properties of the fibers were determined using a fiber tensile strength tester. Results showed that the HOT-PRs successfully used the phenolic hydroxyl groups and the hydroxyl groups in the methylol groups to promote the ring-opening reaction of the epoxy groups to form ether bonds. The breaking strength of the thermally cured fibers was 206 MPa, and the elongation at break was 14.5%. The microwave-cured fibers had good heat resistance with an initial weight loss temperature of 315°C and a char yield of 59.7% at 800°C.

Glycidyl azide polymer (GAP) with tetra hydroxyl functional groups often known as tetra functional GAP or t-GAP is a potential energetic polymeric binder for high-energy composite solid rocket propellant and plastic bonded high explosive formulations. t-GAP is synthesized via azidation of the tetrafunctional precursor of poly-epichlorohydrine (t-PECH) by sodium azide in DMSO. In this article, synthesis of t-GAP is studied using IR-spectroscopy, and an attempt is made to monitor the reaction progress through characteristic IR absorption bands corresponding to C–N₃ in t-GAP and C–Cl in t-PECH vibrations aiming to optimize reaction parameters.

In order to evaluate the bio-degradation performance of different kinds of poly(lactic acid) (PLA) rapidly, a new method, called hydro-thermal degradation was developed. Four kinds of commercial grade PLA were analyzed by both bio-degradation and hydro-thermal degradation with their degradation performance investigated via weight loss (%), infrared spectra (IR), size-exclusion chromatography (SEC), and X‑ray diffraction measurements (XRD). The experimental results showed that the bio-degradation performance, which would take several years to degrade totally, could degrade in a short time (2 h) at 170°C by the hydro-thermal degradation. The order of the degradation rate is Revode101 > Revode210 > Revode190 > Revode290, corresponding with the structure characteristics of them. Thus, this new method provides a simple and effective way to degrade the PLA rapidly and to evaluate its bio-degradation performance.

The features of radical polymerization of methyl methacrylate involving phenazine as photocatalyst, under UV irradiation, have been investigated. It has been found that the phenazine-based compositions allow initiation of the methyl methacrylate polymerization and, in certain cases, performing it in a controlled regime. It has been shown that it is possible to prepare poly(methyl methacrylate) over sufficiently wide range of molecular mass by adjusting the composition of the phenazine + organobromine compound + tertiary amine catalytic system, the obtained polymer being prone to further modification via block copolymerization. A specific feature of the suggested catalytic compositions is the possibility of the polymer synthesis to high conversion using a low concentration of the catalyst and without prior degassing of the reaction mixture.

A cooligomer has been synthesized with a yield of 93% by triple condensation of 2-allylphenol, formaldehyde, and ethylenediamine (0.5 : 4.0 : 1.0). The molecular weight and molecular weight distribution of the product were determined (M_w = 860 and M_n = 470), and it was revealed that cooligomer has sufficiently high thermal stability (a significant loss of cooligomer mass was observed at ~400°C). Thermal self-crosslinking (up to 280°C) of the cooligomer and its crosslinking with acrylonitrile in the presence of the initiator benzoyl peroxide (1%) followed by hydrolysis of the resulting polymer in the presence of KOH were carried out. Their structure was studied by IR spectroscopy. The sorption properties of the crosslinked hydrolyzed polymer were examined for the extraction of uranyl ions from model aqueous systems under batch conditions at various pH values, concentrations, and sorption times. It has been found that the maximum recovery of uranyl ions by the hydrolysis product of the crosslinked polymer at pH 7 is 90.8% and the sorption capacity is 203.5 mg/g. The dependence of the batch (“static”) sorption capacity of the crosslinked polymer on the equilibrium and initial concentration of uranyl ions was considered. It has been shown that the sorption capacity stabilizes at ~300 mg/g. The sorption properties of the crosslinked polymer were confirmed by both IR spectroscopy data and by the results of energy dispersive X-ray spectroscopy and scanning electron microscopy.

In this study, VO_x was prepared by oxalic acid and vanadium pentoxide under nitrogen atmosphere and SiO₂ was grown on the surface of VO_x. Block copolymer (PCL-b-PDMS-b-PCL) was synthesized by hydroxy terminated poly(dimethylsiloxane) and caprolactone, and the composite material containing inorganic particles was obtained by blending VO_x/SiO₂ with PCL-b-PDMS-b-PCL. The porous film was constructed by breathing pattern method, and the supersmooth surface was obtained by injecting lubricating oil into the porous film. The composite was tested by Fourier transform infrared spectroscopy, hydrogen NMR spectroscopy, scanning electron microscopy, contact angle and anti-bacterial adhesion. The results showed that PCL-b-PDMS-b-PCL was successfully synthesized, and the prepared composite material containing inorganic particles had excellent superslippery properties after oil injection, and the sliding angle was 2°.

This study details the synthesis of organic/inorganic hybrid materials by combining the conductive polymer poly(m-aminophenol) (PMAP) with SnO₂ metal oxide. The objective is to broaden the polymer’s environmental applicability and evaluate its adsorption capabilities, focusing on dyes such as Methylene Blue (MB) and Congo Red (CR). The nanocomposite is meticulously formed through in situ polymerization of m-aminophenol in the presence of SnO₂, with varying loading ratios (1, 3, 10%). Extensive characterization, including analytical techniques (IR and XRD), confirms the structural integrity of the synthesized materials. X-ray diffraction (XRD) analyses distinctly show the successful combination of SnO₂ with the polymer matrix. Adsorption kinetics and isotherm were implemented to understand the adsorption mechanism for both dyes. It was found that PMAP/x%SnO₂ nanocomposite materials (with x = 1, 3 and 10) have high adsorption affinity toward MB and low adsorption affinity toward CR. Significantly, the MB removal percentage follows an ascending trend, starting at 85% for pure PMAP and increasing to 89% for PMAP/1%SnO₂, to 92% for PMAP/3%SnO₂, and peaking at 95% for PMAP/10%SnO₂ within 30 minutes. In contrast, CR removal exhibits a lower percentage, with only 54% removal for pure PMAP and a modest increase to 59% for the PMAP/10%SnO₂ nanocomposite, representing a 5% improvement. These outcomes lead to the conclusion that PMAP/x%SnO₂ nanocomposite materials (with x = 1, 3, and 10) exhibit high adsorption affinity for MB and comparatively lower adsorption affinity for CR. The adsorption of MB and CR on the PMAP and on the PMAP/10%SnO₂ nanpcomposite successfully followed the Langmuir adsorption kinetics model, which showed a better fit for the adsorption of MB and CR. The maximum adsorption capacity ({{Q}_{m}}) of MPAP/10%SnO₂ for MB was 76.99 mg/g, while for CR it was 39.56 mg/g.

A series of novel post-metallocene titanium complexes bearing polyfluorinated phenoxy-imines with para-substituents of varying electron-withdrawing (–NO₂, –F) or electron-donating (–OMe, –OEt, ‒OⁱPr, –OPh) properties in N-phenyl fragments were synthesized and used as ethylene polymerization catalysts. Upon activation with modified methylaluminoxane these complexes produce highly crystalline ultra-high molecular weight polyethylene. The resulting catalysts were investigated in terms of the impact of the mesomeric effect of the introduced substituent and the electron unsaturation of the N-aryl fragment on the catalytic activity and molecular weight of the polyethylene produced. A nonmonotonic character of the dependences of the activity of the catalyst and the molecular weight of the synthesized polymers on the electrophilicity of the titanium atom was found. An unexpected increase in polymerization activity was also found in the OAlk series upon the transition from OMe to larger groups. To explain these effects, possible reasons were considered clarifying the details of the studied process. The obtained results demonstrate that fine tuning of electronic features of the phenoxy-imine ligand by altering the para-substituents of N-aryl fragments is a powerful tool for control the activity of titanium catalysts as well as properties of the resulting polymers.

Novel phosphorus–boron–nitrogen-containing products have been developed that promote intumescing and charring of polymer compositions exposed to flame and enhance their fire and heat protective and adhesive characteristics. The structure of these products has been studied, and their fabrication conditions and basic properties have been determined. The results of research and development of a number of fire-and-heat retardant materials, in particular, rubber protection coatings based on polychloroprene and chlorosulfonated polyethylene and perchlorovinyl resin-based protective coatings for fiberglass and elastomeric materials, are summarized. The possibility of using phosphorus–boron–nitrogen-containing products as sizing agents for fillers, such as microfibers and microspheres, is described.

The use of reactive copolymers of glycidyl methacrylate and alkyl methacrylates differing in the length of the alkyl substituent (С6–С18) has been suggested as alternative to fluorinated modifiers to efficiently reduce the surface free energy. The influence of the structure and composition of the copolymers on the surface free energy and the work of adhesion to polar and dispersive test liquids has been demonstrated. At a smooth surface, the polymer coatings based on the functional copolymers have exhibited low surface free energy (down to 19 mN/m) and to ensure the high-hydrophobic wetting state with contact angles up to 105°. The stability of the superhydrophobic state of the polymer coatings at the textured aluminum surface (the AMG2M grade) with initial wetting angles up to 168° has been investigated.