Polymers最新文献

This study evaluates 10 bar water aging effects on reciprocating tribology of FDM-printed PLA and PLA with 10 and 15 wt.% glass fiber (GF). Water uptake was Fickian, and saturation mass rose from 0.0845 g (PLA) to 0.1625 g and 0.295 g (10 and 15 wt.% GF). Reciprocating tests at 40 N over 100 m at 0.5 and 1 Hz showed immersion time drives coefficient of friction (COF) and wear. At 0.5 Hz, neat PLA stabilized at COF 0.65 to 0.70 but increased to about 0.75 to 0.80 after 7-day; PLA + 10 wt.% GF reached about 0.80 to 0.82 after 14-day to 28-day. GF reduced unaged wear depth from about 125 µm to about 85 to 96 µm, yet 28-day aging increased depths to about 129 to 132 µm for both GF levels at 0.5 Hz. At 1 Hz, neat PLA peaked at about 235 to 240 µm depth after 7-day, whereas 15 wt.% GF reached about 160 µm after 28-day. Factorial analysis showed that wear scar width was primarily influenced by immersion time, accounting for 76.02% of the variation in the data, clearly evidencing strong dependence on the environment. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), glass transition temperature (Tg), and the melting temperature (Tm) support the occurrence of a transition from volume to interface-dominated damage with aging, while Tg and Tm remain unaffected.

Natural fabrics such as cotton and silk have been widely used due to their excellent properties, but their tendency to wrinkle limits their value. Traditional anti-wrinkle finishing agents suffer from issues like formaldehyde release and performance imbalance. This paper reviews the advances in anti-wrinkle finishing of cotton and silk fabrics, analyzing from the perspectives of environmentally friendly finishing agents, physical properties balancing, sustainable anti-wrinkle finishing, and synchronized multi-functionality. Current research have developed various environmentally friendly formaldehyde-free finishing agents, such as carboxylated polyaldehyde sucrose and α-lipoic acid, through strategies including natural product modification and organic-inorganic hybridization. The application of these agents can enable fabrics to achieve a balance between wrinkle resistance, mechanical properties, hydrophilicity, and resistance to yellowing properties. Simultaneously, they also overcome the limitations of traditional processes, endow fabric with integrated application of wrinkle resistance alongside functions such as dyeing, flame retardancy, and antibacterial properties. Moreover, optimization methods such as response surface methodology (RSM) have facilitated the precise regulation of process parameters. Future research should continue to focus on greenization, high performance, and multi-functional coordination, deepen molecular design and process optimization, and provide support for the sustainable development of the textile industry.

This study systematically investigates the influence of short carbon-fiber (SCF) content on the mechanical, thermal, and tribological properties of self-lubricating polyphenylene sulfide (PPS) composites filled with PTFE and MoS2, addressing the critical need for high-wear resistance in Carbon-Fiber-Reinforced Thermoplastic (CFRTP) structural applications. The results identified 10 wt% SCF as the optimal content that achieved the best balance between load-bearing capacity and friction performance. The coefficient of friction μ and wear amount were reduced by 29.28% and 29.29%, respectively, compared to the PPS/PTFE/MoS2 composite material without SCF, and by 14.67% and 20.75%, respectively, compared to the material with excessive SCF filling (20 wt%). Finite-Element Analysis-Representative Volume Element (FEA-RVE) reveals the mechanism by which excessive content of SCF at the microscopic level leads to a slight decrease in mechanical properties. Critically, the tribological performance exhibited a discrepancy with bulk mechanical properties: above 15 wt% SCF, the wear rate worsened despite high mechanical strength, revealing that increased fiber agglomeration and micro-abrasion effects were the primary causes of performance deterioration. Further in-depth XPS analysis revealed a synergistic lubrication mechanism: In the optimal sample, an ultra-dense PTFE transfer film was formed to mask the underlying MoS2. This masking, coupled with the high surface activity of MoO3 particles leads to stronger physicochemical interactions with the polymer matrix, ensures the exceptional durability and stability of the tribo-film. This research establishes a complete structure-performance relationship by integrating mechanical, thermal, and tribo-chemical mechanisms, offering critical theoretical guidance for the design of next-generation high-performance self-lubricating CFRTPs.

Polymer-based bioactive composites are one of the most rapidly advancing areas in contemporary regenerative medicine. This review aims to identify major trends and knowledge gaps in the development of bioactive polymer composites and examine their translational relevance from a materials design perspective, with a specific focus on synthetic thermoplastic polymer matrices suitable for load-bearing bone scaffold applications and filament-based additive manufacturing. A total of 546 publications spanning 2016-2025 were screened, with 106 selected according to predefined relevance criteria. Bibliometric and content analyses were performed to delineate the primary research trajectories of bioactive composite materials. The results revealed that the majority of studies focused on composites comprising synthetic aliphatic polyesters, primarily polylactic acid (PLA) or polycaprolactone (PCL), reinforced with hydroxyapatite (HA) or bioactive glass (BG), which confer osteoconductivity but rarely achieve multifunctionality. Antimicrobial agents, ion-releasing components, and naturally derived bioactive molecules-associated with biointeractive functionalities and reported effects related to osteogenesis, angiogenesis, and immune modulation-are significantly underrepresented. Fewer than 20% of the investigated studies include in vivo validation, underscoring considerable scope for further preclinical and translational research. This work consolidates current trends in synthetic bioactive polymer composite design and identifies critical directions for future research. The findings of this review provide a structured framework to support the selection of composite fabrication and modification strategies, functional additives, and targeted biological functionalities for next-generation, load-bearing bone tissue engineering materials.

Insufficient osteogenic activity and mechanical properties of poly-L-lactic acid (PLLA) are urgent problems to be solved in deepening their application in bone tissue engineering. In this work, PLLA/mesoporous bioactive glass (PLLA/MBG) scaffolds and PLLA/simvastatin-loaded mesoporous bioactive glass (PLLA/MBG@SIM) scaffolds with filler content of 5, 10, and 15 wt% MBG and MBG@SIM were fabricated via electrospinning technology. At 10 wt% MBG loading, the tensile strength and tensile modulus were 3.23 ± 0.26 MPa and 124.47 ± 8.68 MPa, respectively, over 50% higher than those of PLLA scaffolds, demonstrating a significant enhancement in mechanical properties. Moreover, the incorporation of MBG improved the bioactivity of the PLLA scaffold, promoting the formation of apatite on the surface of the scaffolds. All composite scaffolds were non-toxic with good biocompatibility. Furthermore, PLLA/MBG@SIM composite scaffolds displayed superior osteogenic effects, better than the pure PLLA scaffolds and PLLA/MBG scaffolds. This work presents a multifunctional scaffold system combining enhanced mechanical strength with potent osteogenic activity, showing great promise for bone tissue engineering applications.

This study aims to examine the effect of additional light curing on the color stability and degree of conversion (DoC) of mono-shade resin composites cured using different light curing units and irradiation levels. Sixty-six disk-shaped samples were prepared for each of the mono-shade (Omnichroma/OC, Vittra APS Unique/VU) and multi-shade resin (Clearfil Majesty ES-2/CME) composites. The samples were randomly divided into three groups and cured for 20 s according to: (1) QTH at 800 mW/cm² (16 J/cm²), (2) LED at 1000 mW/cm² (20 J/cm²), and (3) 1400 mW/cm² (28 J/cm²). After polishing, half of the samples in each group were exposed to additional light curing. Color parameters were measured at baseline and after 28 days of immersion in a coffee solution. CIEDE2000 color (∆E₀₀) and Whiteness Index (ΔWI_D) changes were used to assess color stability. ∆E₀₀ and ΔWI_D were compared with the perceptibility and acceptability threshold. Mono-shade composites exhibited lower DoC with higher ΔE₀₀ and ΔWI_D changes compared to the multi-shade composite. Mono-shade composites showed clinically unacceptable color and whiteness changes. Additional light curing performed using the same protocol both before and after polishing did not contribute to the color/whiteness stability and DoC of either mono-shade or multi-shade resin composites.

Bio-based bismaleimide (BMI) resins can reduce environmental impact and impart intrinsic flame retardancy, but achieving a high glass transition temperature (Tg) remains challenging. Here, we replace the conventional petrochemical co-monomer O,O'-diallyl bisphenol A (DABPA) with a synthesized tri-allyl derivative of curcumin (AEC) in 4,4'-bismaleimidodiphenylmethane (BDM)-based resins. The AEC monomer, synthesized via exhaustive O- and C-alkylation of curcumin, acts as a trifunctional crosslinker. By systematically varying the imide:allyl molar ratio, we optimized the network properties. We optimize the network's thermal and fire-safety properties. The optimized formulation (BDM: AEC = 1:0.87, denoted BA-0.87) yields 43.06% char at 800 °C and reduces the peak heat release rate (PHRR) by 13.2% compared to the conventional BDM/DABPA control (BD-0.87). Meanwhile, BA-0.87 passes UL-94 V-0 with no dripping and attains a Tg above 400 °C-nearly 100 °C higher than BD-0.87. These enhancements arise from curcumin's rigid conjugated structure, which increases crosslink density and promotes char formation during decomposition. Our work demonstrates a viable, bio-derived pathway to engineer BMI resins that simultaneously improve thermal stability and intrinsic flame retardancy. Such resins are promising for demanding aerospace and high-temperature electronic applications that require both fire safety and stability.

Chitinases catalyze the hydrolysis of β-1,4-glycosidic bonds in chitin, a structural biopolymer synthesized by numerous organisms. Although these enzymes have been widely investigated, studies focusing on insect-derived chitinases remain limited. In this study, three recombinant chitinases from the leaf-cutter ant Atta sexdens were cloned, expressed in Pichia pastoris, and biochemically characterized. The enzymes-AsChtII-C2B3 (one catalytic and three chitin-binding domains), AsChtII-C3C4 (two catalytic domains), and AsChtII-C5B1 (one catalytic and one binding domain), exhibited optimal activity at pH 4-5 and 50 °C using colloidal chitin as substrate. Chitinase activity on colloidal α-chitin was confirmed by ¹H NMR (proton nuclear magnetic resonance) spectroscopy, revealing GlcNAc concentrations of 0.41, 0.48, and 0.56 mmol L^-1 for AsChtII-C3C4, AsChtII-C2B3, and AsChtII-C5B1, respectively. Their antifungal activities were evaluated against the human pathogens Candida albicans and Aspergillus fumigatus, as well as the phytopathogen Lasiodiplodia theobromae. Distinct inhibition profiles were observed: AsChtII-C5B1 (150 µg/mL) showed the highest activity against C. albicans (87.6% inhibition), while AsChtII-C3C4 (25 µg/mL) was most effective against A. fumigatus (60% inhibition). Notably, only AsChtII-C2B3 inhibited L. theobromae growth, inducing severe hyphal deformations observed by scanning electron microscopy (SEM). These findings demonstrate that recombinant A. sexdens chitinases exhibit species-specific antifungal properties, underscoring their potential as biotechnological tools for medical and agricultural applications.

Mycelium-based composites (MBCs) are formed from lignocellulosic substrates and biopolymer matrices derived from fungal mycelium. Due to their low fossil energy demand and biodegradability, MBCs represent a versatile and sustainable material suitable for a range of applications, with increasing interest focused on packaging. Hemp fibers are an example of natural fibers with great promise as a substrate to improve the mechanical properties of MBCs. However, the separation of bast and hurd fiber requires processing and commercial-scale facilities that are logistically challenging and may be cost-prohibitive. Here, the potential for minimally processed hemp, with no separation of fibers, is evaluated for the first time to demonstrate feasibility as a substrate for MBCs. Screening included different fiber ratios combined with three different, locally available mushroom strains, which are among the most common in MBC research. The resulting MBCs were tested as an alternative to environmentally harmful expanded polystyrene (EPS, or polystyrene foam), with a focus on compressive strength to reflect load-bearing performance. Some MBCs revealed mechanical performance that met or exceeded EPS, demonstrating the utility of minimally processed hemp fiber in biocomposites for safer packaging.

Out-of-autoclave (OoA) processing has emerged as a promising route for manufacturing high-performance polymer composites while reducing energy consumption and production complexity. The authors investigate the effect of curing temperature on the thermo-mechanical performances of carbon fiber-reinforced composites produced via resin infusion. Five laminates composed of six carbon fiber plies were arranged in a [90/0/45/-45/0/90] lay-up and infused with an epoxy resin cured at 25, 40, 50, 60, and 70 °C. The influence of the processed temperatures of the mechanical properties was evaluated through tensile and three-point bending tests, whereas thermal performance was analyzed using Heat Deflection Temperature (HDT) measurements and differential scanning calorimetry (DSC). The results demonstrate an improvement in stiffness, strength, and HDT with increasing the curing temperature, with the 40-50 °C range yielding the most balanced enhancement in mechanical and thermal responses. DSC analyses confirm that higher curing temperatures promote a more complete crosslinking reaction, consistent with the improved laminate performance. Overall, the findings highlight the critical role of controlled thermal curing in optimizing OoA polymer composite systems and support their suitability for energy-efficient applications.