Journal of Polymer Research最新文献

Deployable structures play a crucial role in space applications, where compact storage and reliable deployment are essential for efficient operation. Shape memory polymer composites (SMPC) present a promising alternative due to their lightweight nature, high strain recovery, and adaptive stiffness. This work presents a comprehensive study of the viscoelastic properties of carbon fibre reinforced shape memory epoxy composites (CFREP) using temperature-step/hold multi-frequency dynamic mechanical analysis (DMA). The experimental study was conducted by performing DMA testing on the composites using a 3-point bend loading and a temperature step-and-hold multi-frequency loading condition. At a given frequency of 1 Hz and a range of temperatures, the storage modulus (E′), loss modulus (E′′) and dissipation factor (tanδ) were studied as important viscoelastic properties. A study was conducted into the effects of temperature and multi- frequency loading (0.1 to 10 Hz) on the CFREP composite E′, E′′ and glass transition temperature (T_g). Further the variation of stiffness with temperature in CFREP composite was predicted using Mahieux Reifsnider stiffness-temperature model. Results show strong temperature- and frequency-dependent viscoelastic behavior, with 1.0 wt% CFREP exhibiting optimal stiffness and damping characteristics. Cole-Cole analysis confirms effective fibre-matrix interaction, while the Mahieux-Reifsnider model successfully predicts stiffness variation with temperature. An SMPC-based hinge integrated with a spring-loaded pin-locking mechanism is proposed for the controlled deployment of solar arrays in antenna systems. The integration of SMPC-hinges in space structures offers significant advantages, including reduced weight, mechanical simplicity, and enhanced reliability, making them highly suitable for next-generation satellite applications.

In this study, the effects of two different organic peroxides, dicumyl peroxide (DCP) and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DPBH), on the curing kinetics, crosslink density, mechanical properties, thermomechanical behavior, energy dissipation, and thermal stability of fluorosilicone rubber (FSR) elastomers were investigated. The compounds were prepared with identical peroxide ratios, and the vulcanization behaviors were analyzed through rheometry and kinetic modeling. The mechanical performance, thermo-mechanical relaxation (TSSR), energy dissipation, and thermal stability were systematically evaluated. The crosslink density was measured using both the Flory-Rehner swelling method and the Lee-Pawlowski-Coran (LPC) approach, highlighting the distinct effect of DCP in promoting a higher chemical crosslink density. The results showed that the DCP-cured elastomer (KAR2) had a faster cure, higher crosslink density, greater hardness, and better thermal resistance compared to the DPBH-cured elastomer (KAR1). These findings underscore the critical role of peroxide type in tailoring the structural and functional performance of FSR-based materials for high-demand applications.

In this study, carbon quantum dots (CQDs) based on weathered coal were synthesized by green oxidation method. Then, polylactic acid (PLA) nanocomposites foams were prepared with CQDs by a supercritical CO₂ autoclave foaming process. Moreover, the impact of CQDs on the mechanical strength, pore density, and foaming rate of PLA was investigated, respectively. Under the optimum circumstances of a melting temperature of 180 °C, a melting time of 3 h, a pressure of 11.7 MPa, a foaming temperature of 120 °C, and a foaming time of 1 h, the foam expansion rate reached roughly 64.92 times. Still, the foaming ratio of pure PLA was only 36.13 times. By adjusting various parameters, the crystallinity of the PLA/CQDs nanocomposites foam was enhanced from 21.38% (pure PLA foam) to 46.7%, and its compressive stress was increased from 78 to 224 kPa, resulting in high mechanical properties and the foaming performance of PLA/CQDs due to the high specific surface area of CQDs. Molecular dynamics simulations analysed the mean displacement of CO₂ molecules within pure PLA molecules and PLA/CQDs nanocomposite foamed materials, yielding diffusion coefficients D of 4.49 × 10⁻² Ų/Ps and 2.794 × 10⁻² Ų/Ps respectively. The incorporation of CQDs promotes strong interactions between CQDs and CO₂ molecules, enabling more controllable regulation of CO₂ molecular diffusion rates and enhancing CO₂ solubility within PLA/CQDs composite nano-foamed materials. This approach achieves high foaming ratios while improving the crystallinity and melt strength of PLA.

This study explores the mechanical performance and energy absorption characteristics of carbon fiber-reinforced nylon composites made with Fused Deposition Modeling (FDM) for high-velocity impact applications. The Response Surface Methodology (RSM) framework was used to optimize the effects of three important process parameters such as printing speed (40–90 mm/sec), bed temperature (80–100 °C), and infill density (20–80%) using a Box–Behnken Design (BBD). Mechanical tests, including tensile, flexural, and impact strength, along with energy absorption measurements, were conducted on printed parts with a gyroid infill pattern. Strong model validity was demonstrated by the statistical analysis, as all responses had R² values greater than 0.98. The findings showed that infill density had a major impact on mechanical and energy-absorbing characteristics. High infill and bed temperatures along with a moderate printing speed produced the best results. Performance metrics were correctly predicted by regression models, and the relationships between process, structure, and property were depicted by contour plots and perturbations. These results show how well-suited carbon nylon FDM components can be for structural uses where higher impact resistance is essential.

The growing demand for advanced medical catheters in minimally invasive surgery underscores the importance of optimizing catheter mechanical properties. Although existing studies have explored various multilayer catheters made from different materials and composite designs, research on poly ether ether ketone (PEEK)-based double-layer catheters remains limited. This work developed a PAKD/PEBA double-layer medical catheter utilizing a combination of plasma surface modification and multi-step grafting. The approach enhanced the interlayer peel strength from 0 N to 6.78 N, meeting the bonding requirements for medical catheters. Moreover, compared to a single-layer PEEK catheter with the same dimensions, the bending stiffness of the PAKD/PEBA double-layer catheter was reduced by 39.65% and the torsional stiffness by 34.14%, resulting in improved flexibility and torsional resistance.

Polypropylene (PP) is a commonly used polymer that offers an excellent balance of physical, chemical, and mechanical properties with outstanding cost savings. Ziegler-Natta (ZN) catalyst systems have been the central technology for increasing polypropylene performance, mainly through improved isotacticity, crystallinity, and processability. In this study, the effect of three external electron donors (EDs), including dicyclopentyl dimethoxy silane (Donor D), cyclohexyl dimethoxy methyl silane (Donor C), and tetraethyl orthosilicate (Donor T), on the structural and physicochemical properties of PP produced by ZN catalyst was systematically investigated. Donor D displayed much higher catalytic results among the tested donors, achieving a catalyst activity of 35.49 kg PP/g cat., and an isotactic index over 98%, clearly surpassing Donor C with its lower activity (down to 13.80 kg PP/g cat.) and worse tacticity (~ 92% for T-Donor). It was further verified by differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and rheological analyses that the addition of Donor D led to higher crystallinity, These results highlight the crucial function of EDs in shaping the microstructure and performance of PP, specifically Donor D could become a powerful candidate for providing high-performance iPP with excellent crystallinity and rheological behavior and good potential for industrial-scale processing.

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This study explores direct ink writing (DIW) based additive manufacturing of a commercially available styrene-ethylene-propylene-styrene (SEPS) block copolymer. To formulate suitable inks used as the feedstock materials for DIW, the interaction of ten distinct solvents with the constituent blocks of the SEPS block copolymer was studied theoretically using Hansen solubility parameter (HSP) analysis, which identified toluene as the most appropriate solvent. The printability of the developed ink was assessed through viscosity measurements, thixotropy analysis and evaluation of shape stability of the extrudate inks. These studies suggested that inks containing 35–40 wt% SEPS exhibited adequate printability and shape stability. The mechanical, physical, morphological properties and defects in the printed samples were also investigated. The printed samples experienced comparatively high shrinkage (~ 26–52%) in thickness direction owing to solvent evaporation. Field emission scanning electron microscopy (FESEM) images revealed good inter- and intra-layer coalescence behaviour. However, pore-like defects were observed in the printed samples and their size and number were found to be strongly dependent on the solvent content in the ink. Samples printed with 35–40 wt% inks demonstrated high elongation at break (~ 900–1000%), tensile strength of 6.1–7.2 MPa, and Shore A hardness values of ~ 62–63.

The selective separation of hexavalent chromium (Cr (VI)) from trivalent chromium (Cr (III)) has become a critical environmental priority due to the extreme toxicity, high mobility, and carcinogenic potential of Cr (VI), in stark contrast to the relatively low toxicity and biological significance of Cr (III). In this context, in this study, a novel polymer inclusion membrane (PIM) based on polysulfone (PSU) incorporating 10 wt% ethylenediaminetetraacetic acid (EDTA) as the extractant agent, was developed using the non-solvent induced phase separation (NIPS) technique to address this challenge. Comprehensive characterization by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), contact angle analysis, and thermogravimetric analysis (TGA) confirmed successful EDTA incorporation, resulting in enhanced hydrophilicity (contact angle reduced to 73°), high porosity (83.70%), and thermal stability up to 320 °C. Batch extraction experiments demonstrated a remarkable selectivity, achieving 50% removal of Cr (VI) within 24 h while maintaining Cr (III) extraction below 1.50%. Permeation experiments revealed higher diffusion coefficients for Cr (VI) (24.07 × 10⁻⁷ cm²·s^− 1) compared to Cr (III) (1.08 × 10⁻⁷ cm²·s^− 1) at 35 °C. In addition, the lower activation energy for Cr (VI) (19.07 kJ·mol^− 1) relative to Cr (III) (25.41 kJ·mol^− 1) further highlights the membrane’s preferential affinity for Cr (VI). These findings demonstrate the strong potential of PSU-based PIM with 10 wt% EDTA as an efficient, sustainable, and selective solution for chromium speciation control in industrial wastewater, contributing to improved environmental safety and regulatory compliance.

Conductive hydrogels represent a pivotal advancement for next-generation wearable electronics. However, simultaneously optimizing mechanical robustness, interfacial adhesion, and electromechanical sensitivity remains a significant challenge. In this study, a multifunctional poly(vinyl alcohol)/chitosan/multi-walled carbon nanotube (PCM) composite hydrogel was developed via a facile freeze-thaw strategy. The resulting PCM hydrogel exhibits reliable adhesive strength (12.1 kPa on porcine skin) with over 70% retention after 10 cyclic attachment-detachment tests. Notably, the hydrogel possesses a high electrical conductivity of 13.2 mS/cm, enabling superior sensing performance with a Gauge Factor (GF) of 5.72 under large strains and excellent durability over 500 cycles. Real-time monitoring of human joint motions (e.g., wrist, finger, and elbow) confirms its rapid response and high signal fidelity. These results underscore the potential of PCM hydrogels as a robust and high-performance interface for sophisticated human-machine interaction and sports health monitoring.

This study focuses on evaluating the abrasion resistance of binary rubber blends composed of natural rubber (NR), styrene–butadiene rubber (SBR), and butadiene rubber (BR), addressing the limited understanding of how different rubber types influence their mechanical performance. The novelty of this work lies in providing new insights into elastomer blend behavior by examining the interrelationship among tear strength, crosslink density, and wear resistance. In addition, the vulcanization behavior and crosslinking density were examined while maintaining a constant carbon black/nanosilica hybrid filler composition across all samples. Vulcanization results showed that NR-containing compounds exhibited the fastest cure time (T90), whereas SBR-containing compounds had one of the slowest. The mass loss of the compound containing 20 phr SBR and 80 phr NR decreased by 61% compared with the NR-only compound, due to the optimal crosslinking density contributed by the SBR component. Similar trends were observed in both SBR and BR-containing compounds, though the abrasion resistance of the BR-containing blends was slightly lower than that of the SBR-containing ones. These findings confirm the potential of SBR and BR for abrasion-resistance applications in rubber formulations. Furthermore, the tear and tensile strengths of the compounds correlated with both crosslinking density and bound rubber, underscoring the role of crosslinking level and crack growth in the abrasion mechanism. Overall, strategically blending elastomers—particularly with increased SBR and BR content—enhances the mechanical and abrasion properties of rubber composites, making them well-suited for applications requiring high durability and wear resistance.