Polymer Bulletin最新文献

The study presents a predictive approach for the rheological properties of ionogels (IGs), i.e. storage modulus (G’) and loss modulus (G”), using molecular descriptors and Artificial Neural Network (ANN). A total of 5,670 molecular descriptors, generated via alvaDesc and weighted by mole fraction, serve as input parameters, while experimental G’ and G” values sourced from the literature used as outputs. The collected data are divided into training, validation, and testing sets for ANN model development. Hyperparameter optimization using a grid search with the Levenberg-Marquardt algorithm (LMA) achieved a coefficient of determination (R²) of 0.88 and mean squared error (MSE) of 6.9 × 10^− 9 for 50% reduced Normalised dataset (60/20/20 split, 5 hidden layers, 0.005 learning rate, 32 batch size, 100 epochs). Scaled Conjugate Gradient (SCG) algorithm is further used to improve emission prediction of ANN model to R² of 0.96 and MSE of 2.5 × 10^− 9 using a network architecture with 3 hidden layers containing 25 neurons each, trained over 200 epochs. In classification tasks, the Terpyridine-3-butylimidazolium salt (Tpy) gelator exhibited the best performance for G’ and G” (R² = 0.98 and 0.95). For hydrophobic ionic liquids (ILs), the perfluorobutanesulfonate (C₄F₉SO₃) group achieved R² of 0.98 for both moduli, while for hydrophilic ILs, (bis(trifluoromethylsulfonyl)amide (TFSA) systems showed R² of 0.96 (G’) and 0.98 (G”). These findings demonstrate the potential of descriptor-based ANN models for predicting IG rheological behaviour and supporting material design.

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Present research focused on the formation and effect of melamine–formaldehyde self-healing microcapsules on the mechanical performance of sisal, hemp and abaca reinforced epoxy composites. Self-healing microcapsules were formed by combining 3.12 g of melamine–formaldehyde and 0.75 g of copolymer in deionized water, followed by mixing the solution with bafflers inside a cylindrical vessel. In mechanical tests, Sisal/Epoxy/Self-healing Microcapsules (SESM) composite demonstrates the highest elongation at break of 9.21% while Abaca/Epoxy/Self-healing Microcapsules composite exhibits the highest young’s modulus of 916.4 MPa. Tensile strength of SESM composite leads with a maximum value of 79.56 MPa. The highest value of flexural strength, flexural modulus and hardness was observed in the Sisal/Epoxy/Healing Agent (SESM) composite at 75.37 MPa, 2.96 GPa and 97 Shore-D. Hemp/Epoxy/Self-healing Microcapsules (HESM) composite exhibits the highest impact strength at 22.3 kJ/m². The highest surface roughness of 0.58 µm was observed in the SESM composite. The Sisal/Self-healing Microcapsules composite exhibited the highest fatigue resistance, withstanding 3312 cycles, followed closely by HESM (3167 cycles) and SE (3017 cycles) while SESM composite displayed the lowest creep strain across all time points, beginning at 0.022 (2000s) and reaching only 0.309 (15,000 s). SESM composite exhibited the highest thermal conductivity at 27.65 W·m⁻¹·K⁻¹.

The mechanical and functional performances of epoxy-based composites reinforced with cluster bean stem microfibers and balloon vine stem-derived lignin were evaluated through tensile, flexural, impact, hardness, fatigue, creep, and water absorption tests, conducted in accordance with relevant ASTM standards. The primary objective of the study was to investigate the effect of silane surface treatment on the overall performance of the composites. Reinforcing materials were treated using 3-glycidyloxypropyl trimethoxysilane (3-GPTMS), and composites were fabricated via the conventional hand lay-up technique. The performance of both untreated and silane-treated composites was compared to a reference sample made with 100 vol% epoxy resin to assess the effectiveness of silane treatment. Among the tested samples, the silane-treated composite MF12 exhibited superior mechanical properties, with a tensile strength of 135 MPa, flexural strength of 160 MPa, and impact energy absorption of 4.65 J. In terms of fatigue performance, MF12 also showed the longest fatigue life, withstanding 25,090 cycles at 25% UTS, 27,058 cycles at 50% UTS, and 26,672 cycles at 75% UTS. The failure mechanisms under mechanical loading were examined using scanning electron microscopy (SEM), revealing improved fiber-matrix interaction in the treated composites. Additionally, the silane-treated composite MF23 demonstrated excellent creep resistance, with the lowest recorded creep strain values of 0.0035 at 5000 s, 0.0118 at 10,000 s, and 0.0126 at 15,000 s, along with a high surface hardness of 94 Shore D and lowest water absorption percentage of 2.8%.

Polymers play an important role in the development of organic light emitting diodes (OLEDs) because of their light weight, flexibility, solution processability, outstanding photophysical properties, stability and improved device efficiency. Perylene bisimide (PBI or PDI) derivatives have become attractive options for OLEDs due to their excellent electron transport properties, high thermal and photochemical stability, high fluorescence efficiency and tunable optical properties. But the synthesis of PBI polymers with solution processability is still existing as challenges which prevent their wider use. Most of the reported PBI polymers showed poor solubility due to strong π-π stacking, which prevent them to process using low-cost fabrication techniques like spin coating or inkjet printing. This study addresses this issue by the synthesis of an amino acid-based PBI copolymer using the condensation polymerization reaction between hydroxyl group functionalized PBI derivative and amino acid-based esters. The chemical structure of polymer is studied by using Infrared spectrometer and molecular weights were determined by using Gel Permeation Chromatography (GPC). This polymer is soluble in common organic solvents like chloroform, acetone, tetrahydrofuran etc. Thermogravimetric Analysis (TGA) studies showed that this polymer is stable up to 345 °C. The polymer demonstrated strong light absorption in the UV-visible region from 300 nm to 600 nm range and strong fluorescence emission from 500 nm to 700 nm range. This polymer showed strong fluorescence emission even in solid state, with quantum yield of 14.50%. It showed green emission in solution state and strong red emission in solid state. The solution processability, absorption and emission properties of this polymer offering a new material for OLED application.

Biocompatible nanocomposites represent a viable alternative to improve the properties of common dental materials. In this work, we report nanocomposites based on poly(methyl methacrylate) (PMMA) doped with molybdenum disulfide (MoS₂) nanostructures. The MoS₂ nanostructures were synthesized via hydrothermal synthesis and subsequently incorporated into the PMMA matrix through in situ suspension polymerization, yielding PMMA/MoS₂ nanocomposites with MoS₂ concentrations of 25, 50, and 100 µg/mL. XRD and FTIR analysis confirmed the successful polymerization and interaction between the MoS₂ nanostructures and the PMMA matrix. TGA analysis showed that the PMMA/MoS₂ composites exhibit thermal stability above 200 °C, UV–vis diffuse reflectance spectroscopy (DRS) of the PMMA/MoS₂ nanocomposites revealed a bathochromic shift, indicating a reduction in the optical band gap, in all nanocomposites, especially in the composites at 25 µg/mL and 50 µg/mL of MoS₂. This effect may be attributed to the effective dispersion of MoS₂ nanostructures within the PMMA matrix. These findings were supported by SEM analysis. Cytotoxicity tests conducted with human gingival fibroblasts (HGF) demonstrated that composites containing up to 100 µg/mL of MoS₂ may be biocompatible with HGF cells under acute exposure conditions, in both direct and indirect contact, making PMMA/MoS₂ composites promising candidates for potential dental applications.

In this study, poly(lactic acid) (PLA) composites reinforced with river tamarind bark microfibers and Parthenium hysterophorus-derived lactones were fabricated for food packaging applications. The reinforcing agents were isolated from biomass using chemical methods and incorporated into PLA, and test specimens were prepared following ASTM standards. Surface morphology was examined using scanning electron microscopy, while tensile, flexural, impact, and hardness tests were conducted to evaluate mechanical performance. Thermal conductivity, decomposition temperature, and antimicrobial properties were also assessed to determine thermal stability and biostatic activity. The composites were fabricated with PLA as the matrix, reinforced with 30 vol% river tamarind bark microfibers, and varying lactone contents of 0, 1, 3, 5, and 7 vol% corresponding to samples TR, TRL0, TRL1, TRL2, and TRL3, respectively, while neat PLA (T) was used as a control. Among the formulations, TRL2 exhibited the highest tensile strength (155 MPa), flexural strength (189 MPa), and impact energy (4.9 J). TRL3 showed the highest thermal conductivity (0.381 W/mK), while thermogravimetric analysis indicated optimal thermal stability at lower lactone loading (TRL0), with a decomposition temperature of 453 °C. TRL3 also demonstrated superior antimicrobial activity with the largest inhibition zone. The study highlights the novel dual reinforcement strategy using natural fibers and bioactive lactones to simultaneously improve mechanical strength, thermal performance, and antimicrobial properties of PLA, addressing the research gap of multifunctional, biodegradable polymer composites. The combination of high strength, biodegradability, and antimicrobial properties suggests these composites hold strong potential for applications in food packaging, pharmaceuticals, and biomedical fields.

This study investigates the enhancement of mechanical performance and energy absorption in ultra-high-molecular-weight polyethylene (UHMWPE) nanocomposites for high-performance prosthetic applications. Nano-zeolite (NZ) nanoparticles were incorporated into UHMWPE via a scalable melt-blending process. An automated image-processing framework based on scanning electron microscopy (SEM) was developed for nanoparticle detection and sizing, employing K-means clustering, size filtering, and random forest–based diameter prediction. Dispersion analysis using the normalized span index (NSI) identified 3 wt% NZ as the optimal loading (NSI = 4.13). Dynamic mechanical thermal analysis (DMTA) revealed significant enhancements in storage modulus (E′), loss modulus (E″), and damping factor (tan δ), with the highest overall viscoelastic performance observed for the 4.5 wt% NZ nanocomposite. At 25 °C, E′, E″, and tan δ increased by 41%, 89%, and 35%, respectively, compared to neat UHMWPE, primarily due to improved polymer–filler interfacial interactions and enhanced energy dissipation mechanisms. A Bayesian-optimized Least-Squares Boosting (LSBoost) model was developed to correlate microstructural and processing parameters with viscoelastic responses, achieving high accuracy (R² ≥ 0.95, low RMSE) and identifying temperature as the dominant influencing factor. The results demonstrate the applicability of UHMWPE/nano-zeolite nanocomposites in prosthetic limb components, such as shock-absorbing joints and dynamic footbeds, where enhanced stiffness, damping, and energy dissipation are required.

In this study, the end-of-life options of PHBH and PBAT blends fabricated using twin-screw extrusion and injection moulding techniques were investigated. PBAT with high ductility was added to the brittle PHBH at varying ratios to improve its ductility and toughness. It was discovered that the blend comprising PHBH and PBAT in an 80/20 ratio exhibits good tensile strength, tensile modulus, and elongation at break when compared to other blends. The blend exhibited lower thermal stability when compared to neat PHBH and PBAT. The blends were also exposed to QUV radiation for degradation. The thermal stability of the blend was slightly improved with the increased exposure time. Visual analysis revealed photo-oxidative yellowing in the blends, and tensile properties were decreased with increased exposure time. FTIR spectroscopy displayed a carbonyl group at 1720 cm^− 1, confirming the degradation of the material. The results obtained by monitoring the integrity of the materials reveal that the material started biodegrading after 12 weeks and reached 90% in 180 days. The results demonstrate that the processed blends are compostable according to ASTM D5338, making composting a viable end-of-life disposal method for the blends.

Water pollution has remained a pressing global concern, particularly as access to clean water becomes increasingly limited. Wastewater treatment plays a crucial role in ensuring sufficient water can be supplied for daily needs. Membrane technology has become a promising method in ensuring the efficiency of eliminating contaminants from the wastewater, whereby poly(vinylidene fluoride) (PVDF) is commonly used in membrane fabrication. However, PVDF often faces limitations related to fouling, hydrophobicity, and mechanical stability, which can affect its long-term performance. To overcome these limitations, this research aims to develop, characterize, and analyze the performance of PVDF/GO/NC membranes for dye removal. The membranes were developed using the NIPS method, and characterization to determine the physical and chemical properties of the developed membranes was conducted using Fourier transform infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), membrane porosity measurement, and Ultraviolet-visible (UV-vis) spectroscopy. The membrane performance was evaluated through water permeation flux and dye removal efficiency using methylene blue (MB) as a model dye. The incorporation of nanocellulose (NC) and graphene oxide (GO) is expected to enhance the hydrophilicity, antifouling properties, and overall filtration performance of PVDF membranes, offering a more sustainable and effective approach to wastewater treatment.

To achieve higher cyclization and polymerization degrees (DP), oleum is the most commonly used medium for synthesizing aromatic polyoxadiazole (POD) with excellent thermal stability, chemical resistance, and unique electrochemical properties. However, the stringent dissolution conditions and complex polymerization system limited the effective characterization of POD and hindered stable control of the polymerization process. Consequently, the current understanding of its polymerization mechanism and kinetics remains superficial, with even the basic structure of POD being debated. This study employs anhydrous dioxane as a precipitating agent to obtain POD with a defined structure of alternating benzene and oxadiazole rings terminated with carboxyl groups. Furthermore, elemental analysis is used to calculate the DP of isothermal reaction products under varying conditions, yielding an apparent rate constant, the apparent activation energy (95 kJ/mol), and reaction orders for various substrates (2nd order for hydrazine sulfate, 1st order for terephthalic acid, and 3.3rd order for SO₃). The relationship between system viscosity and polymerization degree (η ~ N) was established to address the impact of high conversion rates on mass transfer, and the intrinsic polymerization kinetics were explored through rheokinetics. This validated previous conclusions and yielded the chemical reaction activation energy (177 kJ/mol), an overall reaction order of 3, and optimal ranges for various conditions. Transition state theory analysis attributes the activation energy gap to diffusive entropy penalties. Finally, based on experimental findings, a plausible polymerization mechanism is proposed to account for the system’s complete cyclization, supported by mathematical validation. This study offers significant insights into the polymerization kinetics of POD, advancing the controllable synthesis of high-performance polymers and providing a foundational framework for future mechanistic and material optimization studies.