Journal of Applied Polymer Science最新文献

Efficient hemostasis remains a major challenge in treating noncompressible bleeding wounds, thereby necessitating the development of haemostatic materials with both excellent clotting performance and antimicrobial activity. To address this need, we fabricated chitosan/poly(vinyl alcohol) (CS/PVA) hybrid aerogels with anisotropic structures via sol–gel and freeze-drying methods. The aerogel was further crosslinked through interactions between Fe³⁺, protocatechualdehyde (PA), and chitosan (CS), which imparted antimicrobial functionality. By modulating the PVA content, the aerogels exhibited a fishbone-like axial structure and a uniform radial honeycomb structure (77.8 μm pore size), with an axial elastic modulus that was nearly an order of magnitude greater than the radial elastic modulus. At 66% solid content and 80% compressive strain, the aerogel achieved a compressive stress > 2.2 MPa and toughness of 450 kJ/m³, thereby significantly surpassing those of conventional aerogels. In rat liver hemorrhage models, the CS/PVA aerogel reduced the bleeding volume by approximately 73% and the hemostasis time by approximately 50% compared with those of the blank controls and gelatine sponges. Additionally, it demonstrated strong antibacterial activity against Staphylococcus aureus and Escherichia coli, along with excellent biocompatibility (no cytotoxicity or haemolysis being observed). This multifunctional aerogel demonstrates promising potential for managing noncompressible wound hemorrhage.

The development of large-tow carbon fibers, valued for their low cost and processability, remains a global research priority. This study systematically investigates the applicability of process conditions optimized for 25 K PAN-based carbon fibers to the production of 50 K large-tow fibers, focusing on their structural evolution and correlated performance. Thermal analysis revealed similar thermal behavior for both fiber types, evidenced by comparable initial stabilization temperatures, which is attributed to their identical precursor composition. However, density testing and morphological analysis (SEM/OM) reveal that 50 K fibers exhibit greater stabilization sensitivity and more pronounced core-shell structural differences during stabilization—their core indentation depth increases by 16% compared to 25 K fibers (128 vs. 110 nm). This structural non-uniformity is directly correlated with uneven heat distribution during the exothermic stabilization process. Despite these structural differences, both fibers demonstrated excellent performance stability. Composite material testing results indicate that performance fluctuations for both types can be controlled within 4%. In summary, this study confirms that existing 25 K process conditions can be effectively extended to 50 K large-tow carbon fibers production. It provides critical theoretical and technical support for scaling up efficient manufacturing while maintaining performance standards.

In this study, we provided a post-fabrication modification process to resemble the organic and mineral phases of natural bone by employing gallic acid-grafted chitosan (GA-g-CS) and baghdadite (BAG), respectively. We hypothesized that the simultaneous employment of GA-g-CS and BAG could improve the osteogenic differentiation potency of human adipose mesenchymal stem cells (hASCs), cultured on 3D-printed scaffolds. For this purpose, GA-g-CS was prepared by a free radical reaction. The ¹HNMR, FTIR, and Folin–Ciocalteu analyses confirmed the successful and effective grafting of gallic acid on the chitosan structure. Furthermore, the successful formation of BAG, synthesized by a sol–gel method, was confirmed by XRD, EDX, and FTIR analyses. Four 3D-printed samples, fabricated in this study, were pure PCL and PCL-coated samples, named GA-g-CS, BAG, and GA-g-CS/BAG. The morphology and elemental analysis of fabricated scaffolds were evaluated by SEM and EDX-MAP. Although % porosity was not changed by adding GA-g-CS or BAG, the %water absorption and hydrolytic degradation were enhanced in the presence of GA-g-CS or BAG. Despite the PCL and BAG groups, there was an acceptable % DPPH inhibition in samples containing GA-g-CS. The results of the biological assessments revealed that GA-g-CS/BAG can be a promising candidate for bone tissue engineering applications.

Nanocomposite materials that combine metal oxides with conducting polymers are increasingly explored for multifunctional biomedical applications. Cerium oxide (CeO) nanoparticles exhibit strong redox activity and reactive oxygen species (ROS) modulation, while polyaniline (PANI) offers high electrical conductivity and biocompatibility. Integrating these two materials can potentially yield composites with improved antibacterial and anticancer performance through enhanced charge transfer and ROS generation. In this study, PANI/CeO nanocomposites were synthesized by chemical polymerization and investigated for their structural, optical and biological characteristics. The composites were prepared with different weight percentages of CeO, such as 20%, 40%, 60%, and 80%. FTIR analysis confirmed the presence of Ce–O vibrations in the composite matrix. UV–visible absorption spectra showed a shift toward lower wavelengths. The calculated band gap values were 3.2, 3.1, 3.0, and 2.9 eV, based on CeO content. XRD analysis showed a preferred growth along the (111) plane, which indicated the cubic fluorite structure of CeO. The EDAX results confirmed the presence of cerium, oxygen, and carbon in the prepared samples. FE-SEM images showed spherical morphology with CeO well dispersed in the PANI matrix. The I–V measurements revealed non-linear characteristics with an increase in CeO concentration. The antibacterial activity increased against both Staphylococcus aureus and Pseudomonas aeruginosa with higher CeO content. The 80 wt% CeO composites showed the highest inhibition zone of 22 mm. This same composite showed a strong cytotoxic effect on HCT-116 colon cancer cells with an IC₅₀ value of 15.54 μg/mL. PL spectra revealed a broad emission band due to surface defects and a blue peak at 452 nm. The SAED pattern confirmed the crystalline nature of CeO with cubic symmetry.

Designing char-forming agents as multifunctional components provides a practical direction for developing intumescent flame-retardant materials with excellent fire safety. In this work, a novel bio-based macromolecular charring agent (NL-OH) was synthesized by chemically modifying lignin with pentaerythritol (PER) and melamine (MEL) and compounded with ammonium phosphate (APP) at an optimal ratio of 5:4 to construct an intumescent flame-retardant system (IFRR) for polypropylene (PP). The flame retardancy and mechanism of the fabricated composites were evaluated using LOI, UL-94, TGA, CCT, TG-FTIR, and other techniques. With the synergy between NL-OH and APP, PP composites exhibited outstanding LOI values of 32.9%, significant char-forming ability of 10.71% of char residues, and notable reductions in the peak heat release rate (PHRR) and peak smoke production rate (PSPR) by 46.9% and 80.9%, respectively. NL-OH functioned as both a charring and blowing agent, promoting the formation of an expanded and continuous char layer that effectively insulates heat and suppresses flammable gas release, contributing to the overall fire safety of the material. This study aligns with international efforts toward sustainable and eco-friendly flame-retardant technologies, which provide a theoretical basis for the construction of a dual-source charring agent.

This study pioneers the development of Eudragit/poly(ε-caprolactone) (EU/PCL) nanofibers as a novel carrier for the bioactive flavonoid, 2,3-diphenyl-3-hydroxyflavone derivative. The compound, encapsulated at two concentrations, was evaluated in parallel with diclofenac diethylamine (DEA), a well-known nonsteroidal anti-inflammatory drug (NSAID). Physicochemical analyses confirmed the formation of uniform, bead-free nanofibers with a hydrophobic surface morphology. Drug release investigations highlighted a sustained release profile, with 44.94% of the encapsulated drug released within 40 h in vitro. The release kinetics exhibited an excellent correlation with the Korsmeyer–Peppas model (R ² = 0.9315), suggesting a diffusion-driven mechanism coupled with polymer erosion. Remarkably, the fabricated nanofibers demonstrated anti-inflammatory efficacy comparable to diclofenac sodium, validated through inhibition of bovine and egg albumin denaturation assays. Biocompatibility was further established using HEK-293 cell culture studies, which revealed a high cell viability of 89.99% ± 0.60% across tested concentrations. In addition, the system achieved 68.11% ± 0.23% inhibition of albumin denaturation with an IC₅₀ value of 32.5 ± 0.23 μg/mL, underscoring its potent anti-inflammatory activity. Collectively, these findings establish EU/PCL nanofibers as a promising platform for the sustained delivery of 2,3-diphenyl-3-hydroxyflavone derivative, offering significant potential as a biocompatible and effective therapeutic alternative under in vitro conditions.

Reinforced and toughened polyethylene fishing fibers have garnered increasing attention to meet the operational demands of modern fisheries. In this study, modified ultrahigh molecular weight polyethylene (UHMWPE) granules, incorporating high-density polyethylene (HDPE) particles and 15 wt% granule powder, were prepared to fabricate reinforced polyethylene fibers. Building on this, the effect of thermoplastic elastomer (TPE) toughening modification on the structure and properties of UHMWPE fibers was investigated. Transmission electron microscopy (TEM) revealed that the TPE phases were uniformly dispersed within the continuous UHMWPE matrix, forming a distinct morphology. The degree of orientation (f ₁₁₀) generally increased with rising TPE content, indicating that TPE promotes orientation. The interaction between TPE content and drawing ratio (DR) enhanced the knot strength of the blended fibers and reduced the strength loss ratio. This study discusses the effects of TPE content on the morphology, crystalline structure, thermal properties, and mechanical performance of the doped fibers. Based on these findings, a mechanism by which TPE modifies UHMWPE fibers is proposed. The main effects of TPE content and DR, as well as their interaction on tensile properties, have been analyzed using analysis of variance (ANOVA).

When used outdoors, polyethylene (PE) film is exposed to ultraviolet radiation with a wavelength of 300 nm, causing molecular chain breakage and leading to deterioration of the film's mechanical properties. To enhance the film's weather resistance, this study modified nano-ZnO (zinc oxide) using different coupling agents. The ultraviolet transmittance and mechanical properties of PE films modified with nano-ZnO incorporating various coupling agents were investigated. The γ-aminopropyltriethoxysilane coupling agent (KH550) was selected. The KH550-ZnO/PE film achieved a tensile strength of 34.2 MPa while providing effective UV shielding with minimal visible light blocking. The aging behavior of KH550-modified nano-ZnO-filled PE films under indoor accelerated aging conditions was investigated. By comparing the mechanical properties and UV shielding performance of PE films with varying nano-ZnO concentrations, the optimal loading was determined to be 4 wt%. PE films containing 4 wt% nano-ZnO demonstrated superior weather resistance in pure UV aging tests, maintaining 88.22% tensile strength retention after 40 days of pure UV exposure. In thermo-oxidative aging tests without UV influence, the 4 wt% maintained a tensile strength retention rate of 69.23%. However, in the thermo-oxidative photoaging test, the presence of moisture led to increased hydroxyl radical generation under the photocatalytic effect of nano-ZnO. This resulted in degradation of the modified PE film segments by hydroxyl radicals, manifesting as reduced tensile strength. Furthermore, three-dimensional polymer aging visualization revealed that changes in carbonyl and carboxyl groups within the film also followed the aforementioned aging patterns. This work aims to extend the service life of agricultural films used in high-temperature, dry environments by incorporating modified nano-ZnO.

In injection molding processes of semi-crystalline polymers, different cooling rates occur at the mold walls and in the part center leading to an inhomogeneous melt solidification and the formation of locally different spherulitic microstructures. To determine their effect on the local thermo-elastic properties and their impact on the part warpage, a multi-scale simulation scheme is used here to investigate the injection molding of an α-iPP stepped plate. After modeling the melt flow during the injection phase, the residual packing pressure is determined in the cooling phases. Then, the formation of the spherulite microstructure is calculated over a plate section with an athermal nucleation model. Based on the predicted effective lamella properties, the radial spherulite model is extended here. It permits deriving more accurate and less anisotropic effective thermo-elastic properties. The local mechanical properties vary strongly in accordance with the local crystallization degree. A generalized plane strain model is used to predict the warpage and shrinkage of the plate section during the in-mold cooling phase and after ejection. Simulations with either constant, mean properties or local ones show clearly that crystallization-dependent properties predict more accurately the warpage and shrinkage behavior compared to constant properties over the plate section.