Journal of Polymer Research最新文献

A novel naphthoxazine monomer and its corresponding polybenzoxazine thermoset were synthesized from 2-naphthol and 2-aminoterphthalic acid. The chemical structures were confirmed using FTIR and NMR spectroscopy. Differential scanning calorimetry (DSC) revealed that thermal ring-opening polymerization occurred at approximately 180 °C without the use of an external catalyst, facilitated by the presence of carboxylic acid groups. The polymerization kinetics were examined using time-resolved ¹H-NMR spectroscopy, and the curing behavior was further analyzed using FTIR and DSC measurements. Thermogravimetric analysis (TGA) demonstrated the excellent thermal stability of the cured thermoset, showing 5% and 10% weight losses at 360 °C and 414 °C, respectively, with a char yield of 9% at 700 °C. Comparative analysis with unsubstituted naphthoxazine analogs revealed a marked enhancement in thermal stability, attributed to the synergistic effect of the rigid naphthalene backbone and the dicarboxylic acid functionalities. This combination makes the resin a better option for high-performance thermosets by producing noticeably higher decomposition temperatures and enhanced thermal resistance. 

This study investigates the synthesis and characterization of novel hydrogels based on hydrolyzed polyacrylonitrile (HPAN) and epichlorohydrin (ECH), aimed at enhancing water retention in soil and supporting controlled sorption of aqueous contaminants. The hydrogels were prepared via a batch reaction in an aqueous medium at 70 °C, employing three different amine crosslinkers (monoethanolamine, diethanolamine, and triethylenepentamine) to explore the effects of branching and network structure on material properties. Characterization by Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of covalent bonds between ECH and amine groups, while scanning electron microscopy (SEM) revealed porous morphologies whose size and distribution depended on the type of amine. Equilibrium swelling capacities ranged from 370 ± 10% for HPAN-MEA to 4.85 ± 0.12 g/g for HPAN-TEPA, with kinetic measurements showing that 90% of maximum swelling was reached within 20–30 min, indicating rapid water uptake relevant for irrigation applications. Mechanical testing indicated that all hydrogels maintained elasticity under up to 80% compression, with modulus values increasing with crosslinker branching. Preliminary biocompatibility assessment via seed germination tests showed no significant toxicity, and residual ECH content was below 0.01%, suggesting environmental safety. Comparative analysis with other crosslinkers demonstrated superior swelling, porosity (78 ± 5%), and low density (0.86 ± 0.03 g/cm³) for ECH-based hydrogels. Furthermore, HPAN-TEPA hydrogels exhibited sorption capacities toward Cu²⁺ ions up to 128 ± 6 mg/g and maintained over 92% functionality after five swelling–drying cycles, indicating good stability and recyclability. Cost and performance benchmarking suggest that these hydrogels are competitive with commercial polyacrylate-based superabsorbents while offering tunable properties through selection of amine crosslinkers. These results provide a foundation for the design of HPAN–ECH hydrogels with tailored sorption and swelling behavior, highlighting their potential for agricultural water management and environmental remediation, while acknowledging the need for further studies on large-scale application, long-term durability, and comprehensive biodegradability.

Bifunctional reactive cyclic carbonate compounds were synthesized and introduced into the epoxy system acting as diluting plasticizer and toughening agent to improve their plasticity and flexibility. Effects of content and structure of cyclic carbonates on the processibility, mechanical performances and thermal properties of the materials were investigated. An impressive improvement in viscosity reduction and mechanical performances is observed by loading of cyclic carbonate. The modified epoxy resin composites exhibit a significant enhancement in mechanical properties at a 30 wt% loading of cyclic carbonate with the tensile strength 170.6% higher than the original resin and 23.9% improvement in the flexural strength. The enhancement in material performance can be attributed to a combination of factors: the presence of soft segments, hydrogen bonding interactions, decrease in crosslinking density, and the plasticizing effect of unreacted components. Moreover, the thermal properties like degradation temperature, T_g temperature and thermo-mechanical properties of epoxy resin composites were also affected by the introduction of cyclic carbonate.

Phase change materials (PCMs) hold tremendous potential in sustainable energy utilization, with green preparation and efficient application emerging as key research hotspots in this field. However, PCMs face two persistent challenges in practical use: liquid leakage when temperatures exceed the melting point, and the inherently low thermal conductivity of PCMs. Therefore, we prepared a shape-stable SA/PEG/PDA@CNTs (SPC) composite phase change material using bio-based sodium alginate (SA) as the carrier material, polyethylene glycol (PEG) as the phase change component, and polydopamine (PDA)-modified carbon nanotubes (CNTs) as the functional filler. The results indicate that SPC2 possesses a high phase-change energy storage density, with a melting enthalpy of 137.8 J/g. The introduction of PDA-modified CNTs (PDA@CNTs) significantly improved the thermal conductivity of SPC2, increasing its thermal conductivity by 108%. Meanwhile, PDA@CNTs endow SPC2 with photothermal conversion capability, achieving a photothermal conversion efficiency of 88.4%. Therefore, composite phase change materials designed using this method have advantages such as environmental friendliness, low cost, and excellent thermal performance. Furthermore, this material has promising application prospects in fields such as solar energy utilization, industrial waste heat recovery, and thermal management of electronic devices.

This study explores a surface functionalization approach using stearic acid to enhance the performance of polypropylene (PP)-based nanocomposites reinforced with titanium dioxide (TiO₂) nanostructures. Both untreated and stearic acid-treated TiO₂ were incorporated into the PP matrix to systematically investigate their influence on the multifunctional properties of the composites. Comprehensive characterization was carried out to assess the effects of surface treatment on structural, morphological, electrical, and mechanical behaviors. Fourier Transform Infrared (FTIR), and X-ray Diffraction (XRD) analyses confirmed the successful surface modification of TiO₂ and its influence on the crystalline structure of the polymer matrix. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) observations revealed improved nanoparticle dispersion, reduced agglomeration, and enhanced interfacial compatibility in composites containing treated TiO₂. Electrical conductivity measurements showed significant enhancement with increasing TiO₂ content, particularly in treated systems, due to better nanoparticle distribution. Rheological and impact resistance analyses indicated that surface-modified TiO₂ preserved flow properties at low filler content and improved toughness at higher loadings. These results demonstrate that stearic acid-modified TiO₂ can serve as an effective strategy for improving the multifunctionality of PP-based nanocomposites.

Addressing the technological challenges in the automotive industry concerning energy consumption, environmental protection, aging susceptibility, and safety, this study focuses on the lightweighting and UV-resistant modification of polypropylene (PP)-the most widely used and highest-volume polymeric material in automotive plastics. Such design holds critical significance for the green transformation of the automotive industry. The research employs hollow glass beads (HGB) and titanium dioxide (TiO₂) as functional fillers, and successfully develops a novel PP-based composite material through surface grafting modification of HGB using tetrabutyl titanate (TBT). The results indicate that the coupling agent TBT uniformly coated the surface of HGB via chemical bonding, significantly enhancing the interfacial interaction between the filler and the PP matrix, thereby laying the foundation for improved mechanical properties of the material. The self-lubricating effect of TiO₂ effectively reduces intermolecular friction within the system, elevating the MFR of the composite material to 15.43 g/10min, thus significantly improving its processability. After undergoing 100 h of artificial accelerated hygrothermal aging tests, pure PP specimens exhibit obvious cracking and performance degradation, whereas the PP/TBT-HGB/TiO₂ (0.50 wt%) composite material shows no visible surface cracks and maintains excellent mechanical property retention, with a flexural strength of 59.54 MPa, flexural modulus of 1842 MPa, tensile strength of 35.24 MPa, impact strength of 23.58 kJ/m², and a reduced density of 0.886 g/cm³. Compared to traditional PP materials, this composite material not only meets the lightweighting demands of the automotive industry but also enhances weather resistance through the synergistic UV-resistant effect of TiO₂. Its balance of low density and excellent mechanical properties demonstrates significant engineering application advantages in terms of achieving carbon neutrality goals and optimizing overall performance.

Furfural residue (FR), a major lignocellulosic byproduct of industrial furfural production, poses significant environmental challenges due to its disposal via landfilling or incineration. To valorize this underutilized resource, this study presented a sequential acid-periodate approach for extracting dialdehyde-functionalized cellulose nanocrystals (FR-DCNC) from FR. The process initiates with efficient delignification using formic acid/hydrogen peroxide (FA/H₂O₂) pretreatment, yielding purified cellulose (FR-C) with minimal lignin content. Subsequent sulfuric acid hydrolysis liberated cellulose nanocrystals, which were selectively oxidized by sodium periodate to introduce aldehyde functionalities via C2-C3 bond cleavage. Comprehensive characterization revealed that FR-DCNC exhibited high crystallinity (78.6%), a rod-like morphology (diameter = 12.6 nm), and an exceptionally high specific surface area (289 m²/g). FTIR confirmed successful dialdehyde formation while thermogravimetric analysis demonstrated enhanced thermal stability (T_max=221 °C) compared to raw FR. The introduced aldehyde groups (2.6 mmol/g) endow FR-DCNC with high surface reactivity for advanced applications in polymer composites, adsorption, and functional materials. This work establishes a sustainable pathway to transform industrial biowaste into high-value functional nanomaterials, aligning with circular economy principles.

The growing demand for sustainable materials with competitive performance drives research into natural fiber-reinforced composites, a promising alternative to synthetics. Optimizing their properties and expanding applications depend on various factors, such as reinforcement configurations and architectures. Thus, investigating hybrid composites combining jute and flax is strategic for advancing composite materials knowledge and offering solutions to engineering challenges. This study examines the effects of unidirectional (UD) and twill flax reinforcements on the mechanical properties of interlaminated jute/flax hybrids produced by compression molding. Composites were developed with a fixed core of five layers of bidirectional jute fabric, symmetrically covered by one to three external UD or twill flax layers. The influence of flax fabric architecture and number of external layers was assessed by tensile, flexural, and impact tests using a neat jute composite as reference. Results showed that both fabric architecture and number of layers significantly affected mechanical properties. Tensile strength and stiffness increased nearly monotonically with more flax layers. Flexural tests revealed substantial improvements, with a plateau between two and three layers. Under impact, all hybrids outperformed neat jute, with three-layer samples achieving the best results. Overall, hybrids reinforced with UD flax exhibited superior performance across all properties. These findings highlight flax reinforcement’s potential to enhance natural fiber composites for diverse applications.

Polyester, the most widely used synthetic fibre, has been challenging to dye sustainably with its hydrophobic surface and low reactivity, necessitating energy- and resource-intensive high-temperature high-pressure (HTHP) dyeing processes. Enzymatic surface modification with esterase was investigated as a green method to enhance the dyeability of polyester with reactive dyes. Development of -OH and -COOH groups was successfully confirmed by FTIR. A machine learning model, Extreme Gradient Boosting (XGBoost), was trained to predict the concentrations of -OH and -COOH groups (in mmol/g) and the color strength (K/S value) for modified polyester. A data set consists of 351 experimental data points, each experiment repeated 3 times, comprising process parameters (esterase (%), time, temperature, and pH), was used to train and evaluate the model. Strong predictive capability was demonstrated by the model, with R² values exceeding 0.9 for -OH, -COOH, and K/S. Interpretability by SHAP analysis identified enzyme concentration as the most influential factor, followed by pH, time, and temperature. Residual analysis confirmed normally distributed errors and small deviations of approximately 2 mmol/g for more than 90% predictions, affirming the robustness of the model. Improvement in wicking height, absorbency, and reduced contact angle demonstrated enhancement in hydrophilicity, without affecting the tensile strength. Thermal analysis using DSC revealed melting as well as crystallisation behaviour modifications, complementing modifications at the surface level. Overall, this integrated (enzymatic processing and machine learning) approach for a cleaner production strategy reduces energy usage, minimizes environmental discharge, and presents a viable path toward more sustainable, eco-efficient textile dyeing.

Global water scarcity and soil desertification underscore the critical need for efficient, cost-effective water-retentive materials in sustainable agriculture. To address this, graphene oxide (GO), carbon nanotubes (CNT), and rice husk biochar (RBC) were incorporated into an acrylic acid/2-acrylamido-2-methylpropanesulfonic acid/sodium alginate copolymer network, fabricating three carbon-composite superabsorbent polymers (GO-SAP, CNT-SAP, RBC-SAP). Systematic evaluation revealed that carbon materials dispersed uniformly within the polymer matrix via hydrogen bonding and van der Waals forces, with surface oxygen-containing groups significantly enhancing hydrophilicity. XRD and SEM analyses confirmed amorphous porous structures, with GO-SAP and RBC-SAP exhibiting superior pore distribution. Maximum swelling ratios occurred at loadings of 0.08 g (GO), 0.12 g (CNT), and 0.12 g (RBC). At equivalent loadings, GO-SAP demonstrated the highest absorption capacity, attributable to GO’s strong hydrophilicity, 2D lamellar structure, and exceptional dispersibility. All composites maintained high swelling ratios between pH 5–10 and 20–50 °C but showed sensitivity to multivalent ions. Swelling kinetics followed a pseudo-second-order model (R² > 0.99), indicating chemically controlled absorption governed by hydrophilic groups. Remarkably, the composites retained water for > 4.5 h at 50 °C and preserved > 97% water retention after centrifugation (12,000 rpm). Cyclic stability exceeded 80% of initial swelling capacity after 6 absorption-desorption cycles. This work provides a robust foundation for developing high-performance, sustainable superabsorbents.