Polymer International最新文献

In view of the huge potential in various applications, biopolymer-based polyurethane foams (PUF) are attracting researchers. In the present study, we report the modification of guar gum (GG) via polyaddition reaction with toluene diisocyanate (TDI) using dibutyltin dilaurate as catalyst, silicone oil as surfactant and calcium carbonate as filler to form GG-PUF. The as-synthesized GG-PUF was characterized by Fourier transform infrared (FTIR), XRD, field emission SEM, energy-dispersive X-ray spectroscopy, and surface charge analysis. In the FTIR spectrum of GG-PUF, peaks at 3290, 1705, 1595, and 1510 cm⁻¹ are attributed to stretching vibrations of –NH, –C=O, –C=C– of the benzene ring of TDI, and the –NH bending vibration of the urethane group, respectively. The XRD patterns of GG and GG-PUF indicate their semicrystalline and amorphous nature, respectively. The field emission SEM of GG-PUF exhibits high porosity compared to the smooth surface of GG due to the evolution of CO₂ gas during the foaming reaction. The GG-PUF was evaluated as an adsorbent for cationic dyes from wastewater. The preliminary adsorption studies showed maximum adsorption for malachite green with 93.54% removal at 40 °C and pH 6.0 in 60 min. The adsorption mechanism was studied by various nonlinear kinetic models, namely the pseudo-first order, pseudo-second order and Elovich, and nonlinear isotherm models, such as Langmuir, Freundlich and Temkin. The adsorption followed pseudo-secondorder kinetics and a Langmuir isotherm with a maximum adsorption capacity of 156.44 mg g⁻¹. The small value of the error function (χ²) and normalized standard deviation (Δq%) from nonlinear models indicated the better fitting of the data into nonlinear kinetics and isotherm models. Furthermore, GG-PUF showed substantial degradability under simulated wastewater conditions at acidic and alkaline pH and reusability up to 10 adsorption–desorption cycles. Hence, GG-PUF has tremendous potential as a sustainable, economical and environmentally friendly adsorbent for eliminating cationic dyes from wastewater. © 2024 Society of Chemical Industry.

The seawater desalination industry does not need exotic two-dimensional materials. However, it faces challenges in terms of membrane resilience to stressors such as temperature and oxidation and especially in the area of (bio)fouling. Membrane replacement is a large part of the operating expenditure of modern desalination plants and anything that increases the effective lifespan of a membrane will have economic impact. There are also emerging requirements for membrane selectivity, especially in desalination-adjacent brine-valorisation activities. These challenges provide abundant scope for the exercise of creativity by polymer scientists. © 2024 Society of Chemical Industry.

The precipitation technique was used to prepare calcium hydroxyapatite pectin (CaHAp-Pec) and calcium hydroxyapatite xanthan (CaHAp-Xan) hybrid materials. Chemical analysis, XRD, Fourier transform infrared spectroscopy, specific surface area, TGA and SEM were used to analyze the materials and the organic–inorganic interfaces. XRD and SEM investigations demonstrated that the presence of the biopolymer had an impact on both the structural and morphological properties as well as the crystallinity. The PO₄³⁻ vibration modes are visible in the IR spectra, and new vibration modes mostly associated with Xan and Pec are observed at 1594, 2878 and 3246 cm⁻¹. The specific surface area values were reduced after the chemical functionalization of CaHAp with pectin and xanthan gum. The ability of the three materials CaHAp, CaHAp-Pec and CaHAp-Xan to sorb methylene blue from aqueous solutions was assessed. The adsorption kinetics results best fitted the pseudo-second-order model. The isotherm data agreed well with the Freundlich model. The adsorption capacity values of porous composites CaHAp-Xan 5%, CaHAp-Pec 10% and CaHAp reached 277, 243 and 144 mg g⁻¹, respectively. The non-spontaneous and exothermic nature of the adsorption was demonstrated by the thermodynamic parameters (ΔG⁰, ΔH⁰ and ΔS⁰). Adsorption results confirmed that CaHAp-Xan could be used as an effective adsorbent of cationic dyes from water. © 2024 Society of Chemical Industry.

The use of hybrid fillers provides a new route for improving the friction and wear properties of polymer composites due to their synergistic effect. In the present study, a two-dimensional derivative of MAX phases (MXene) was loaded onto the surface of carbon fiber (CF) and used as reinforcement to modify the tribological properties of epoxy resin (EP) composites. The latter were tested on a plate-on-ring contact configuration as a function of load and sliding speed with reference to composites filled with single carboxyl-terminated butadiene acrylonitrile (CTBN), MXene and CF. It was revealed that, when MXene and CF were incorporated simultaneously into EP/CTBN, the composite's friction coefficient and wear rate were reduced by 55.8% and 96.6% compared to those of EP/CTBN matrix. The mechanisms underlying this improvement are discussed based on a thorough analysis of the morphology of the worn surface and the chemical composition of transfer films. As a result, synergistic interaction between MX@CF and the rubber phase was revealed. © 2024 Society of Chemical Industry.

Plant oil-based acrylic monomers from hydrogenated sunflower (HFM), palm (PMM) and castor (CSM) oils were polymerized to investigate the effect of chemical composition on polymer phase transitions at temperatures relevant to physiological range. While HFM and PMM possess a highly differing content of saturated palmitic and stearic acids combined with unsaturated fatty acids, CSM contains primarily fragments based on monounsaturated ricinoleic hydroxy acid (up to 90%). Differential scanning calorimetry (DSC) measurements indicate that polymers from PMM and HFM are both semicrystalline (with T_m = −6 and −13 °C, respectively), while poly(CSM) appears to be amorphous (T_g = −49 °C). Considering the similarity in polymers' molar mass (M_n = 16 000–20 000 g mol⁻¹), the observed thermal transitions can be explained by the formation of ordered morphological domains due to the presence of saturated palmitic and stearic acid fractions in poly(PMM) and poly(HFM). For copolymers of CSM, PMM and HFM (80 wt% of monomer feed) with styrene, DSC data show two transitions corresponding to the mobility of long alkyl fatty acid side fragments and the macromolecular backbone. For copolymers of PMM and HFM, comparable values (−52.8 and −55.5 °C, respectively) were obtained, while the second transition for poly(CSM-co-styrene) appears at 35 °C. We attribute this higher value to the presence of hydroxyl groups in ricinoleic acid fragments of CSM serving as additional chain transfer sites and the formation of macromolecular fractions enriched with polystyrene fragments. We expect that the temperature transitions obtained can be relevant to the future use of these polymers for biomedical applications, including the synthesis of polymer brushes. © 2024 Society of Chemical Industry.

Thermoplastics based on polyolefins, including polypropylene, high-density polyethylene and low-density polyethylene, are extensively utilized across various packaging sectors. The selection of these materials for specific applications is influenced by multiple factors, such as the polymer's absorption characteristics and the impact on its mechanical properties when in contact with the packaged product. This study presents an experimental methodology designed to simulate the effects of absorption on the macroscopic and microscopic properties of high-density polyethylene bottles in contact with amyl acetate. Macroscopic degradation was evaluated by modeling mechanical damage using unified theory and the energy method. Analytical techniques such as gravimetric analysis, scanning electron microscopy and Fourier transform infrared spectrometry were employed. The findings of this research provide valuable insights for suppliers and industries to experimentally determine the usability and safety intervals of plastic packaging through comprehensive macroscopic and microscopic analyses within relatively short timescales. © 2024 Society of Chemical Industry.

Maleimides are remarkably versatile functional groups, capable of participating in homo- and copolymerizations, Diels–Alder and (photo)cycloadditions, Michael additions, and other reactions. Their reactivity has afforded materials ranging from polyimides with high upper service temperatures to hydrogels for regenerative medicine applications. Moreover, maleimides have proven to be an enabling chemistry for pharmaceutical development and bioconjugation via straightforward modification of cysteine residues. To exert spatiotemporal control over reactions with maleimides, multiple approaches have been developed to photocage nucleophiles, dienes, and dipoles. Additionally, further substitution of the maleimide alkene (e.g. monohalo-, dihalo-, thio-, amino- and methyl-maleimides, among other substituents) confers tunable reactivity and dynamicity, as well as responsive mechanical and optical properties. In this mini-review, we highlight the diverse functionality of maleimides, underscoring their notable impact in polymer science. This moiety and related heterocycles will play an important role in future innovations in chemistry, biomedical, and materials research. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

In this study, a viable route to the development of a high-performance polyoxymethylene (POM)-based nanocomposite is proposed to overcome tribomechanical-related issues in high-precision sliding parts. Prior to melt-blending, graphene nanoplatelet (GNP) filler was processed via a series of liquid-phase exfoliation and surface modification with 3-aminopropyltriethoxysilane. Results indicate that GNP is successfully exfoliated with minimum defect ratio and improves interfacial bonding within the matrix. Uniform dispersion and stable load-transfer capability of POM/GNP with 0.5 wt% loading significantly enhanced flexural, tensile and impact strength by overall 26.4%, in contrast to unfilled POM. Dry friction tests against a steel ball also showed the lowest reduction in friction coefficient and wear rate by 22% and 40.6%, respectively, at the same amount of GNP loading due to the large specific surface coverage and lubricious transfer film chelation onto the steel counterface. Furthermore, dissipated energy accumulation by friction work was calculated in the sliding interfaces based on friction force–displacement hysteresis loop where the POM/GNP 0.5 wt% wear surface consumed ca 21.7% less energy in a dry frictional shearing process compared to neat POM. However, lack or excess loading of processed GNP exhibited insufficient or poor matrix–filler adhesion and led to deterioration of the composite properties due to particle agglomeration which can cause stress concentration and serve as a failure site. The adoption of the proposed methodology would demonstrate excellent material characteristics in thin-walled precision parts where both mechanical and tribological performances are the primary concern. © 2024 Society of Chemical Industry.

Additive manufacturing is a technology that promises to disrupt the conventional manufacturing industry due to its ability to create complex structures with improved macroscopic control not available with existing techniques like molding or milling. In addition to superior macroscopic structural control, photoprinting methods such as digital light projection can enable molecular-scale control over the fabrication process by taking advantage of the self-sorting or assembly properties of the monomers themselves. Polymerization-induced phase separation (PIPS) allows for the remarkable introduction of microscopic control into additive manufacturing, using polymer-rich and polymer-poor regions that rely on incompatibilities to phase separate during polymerization creating new complex materials not achieved by traditional methods. With the incorporation of porogens or filler materials, microporosity and/or surface functionalization can be introduced in a facile one-step printing process. This expands the potential applications of 3D printed materials, to include micro- and macroscale structural control. Using PIPS as a design strategy, polymeric materials with previously unprecedented capabilities can be produced with ease enabling 3D printing to grow into its full potential as a manufacturing tool. © 2024 Society of Chemical Industry.

The utilization of natural polymers in producing electrospun nanofibers has received significant attention due to their biocompatibility, sustainability and diverse range of applications. This research focuses on synthesizing electrospun nanofibers derived from taro starch isolated from tubers. The investigation utilized SEM to examine the structure and size of the electrospun nanofibers. Formic acid and dimethyl sulfoxide solvents were tested to determine the most efficient solvent system for synthesizing taro starch nanofibers. The results demonstrated that the taro starch nanofibers can be effectively synthesized when using formic acid as the primary solvent. The study also investigated the impact of altering the volumetric ratio of formic acid to water on nanofiber morphology and size, finding that a lower formic acid fraction produced smooth fibers while a higher fraction resulted in fused fibers. The electrospinnability was further evaluated by comparing the effects of different isolation agents—distilled water and sodium metabisulfite—during the isolation process. The isolation agent significantly affected the fiber diameter, with notable differences observed in the smoothness of taro starch nanofibers at starch solution concentrations of 13, 15 and 17 wt%. Overall, the results of the study showed that the formation of taro starch fibers was influenced by the type of solvent, the volume fraction of the solvent to water, and the starch isolation agent. Successful fabrication of nanofibers from taro starch and its optimization parameters can contribute to the development of environmentally friendly nanofiber materials and offer a variety of applications in biomedicine, food and environmental engineering, such as tissue engineering, wound dressing, drug delivery, functional food delivery and food packaging. © 2024 Society of Chemical Industry.