Search Results (250)

Hydrolyzed polyacrylamide stabilized oil-in-water emulsions are highly persistent because the polymer strengthens both continuous-phase rheology and the oil–water interfacial film, making demulsification difficult in polymer-flooding produced liquids. Here, an hydrolyzed polyacrylamide degrading bacterium, Delftia lacustris EPDB-8, was isolated, and its ability to destabilize hydrolyzed polyacrylamide-containing emulsions was investigated from molecular, bulk rheological, and interfacial perspectives. EPDB-8 effectively degraded HPAM, causing marked reductions in total organic carbon, total nitrogen, absolute zeta potential, and polymer molecular weight, with an approximately 63-fold decrease after 7 days. SEM, FT-IR, and GPC analyses showed that biodegradation proceeded through deamidation and random chain scission, collapsing the polymer network and generating low-molecular-weight fragments. Driven by bacterial hydrolyzed polyacrylamide degradation, these structural alterations disrupted the viscoelastic composite interfacial film formed by hydrolyzed polyacrylamide and indigenous surface-active species, directly causing emulsion stabilization to shift from polymer-assisted viscous and steric protection to a less effective asphaltene-dominated interfacial structure and thereby accelerating droplet aggregation, coalescence, and phase separation. Although bacterial cells exerted a transient particle-assisted interfacial effect, long-term emulsion stability remained governed by polymer integrity. This study establishes a mechanistic link between hydrolyzed polyacrylamide biodegradation and the rheological and interfacial evolution governing emulsion breakdown, providing a cost-effective and environmentally benign biological strategy for demulsification and treatment of polymer-flooding produced water. These findings offer practical guidance for the design of microbial-based produced-water treatment systems and contribute to the sustainable management of oilfield wastewater generated during enhanced oil recovery operations. Full article

Soil degradation in both agricultural and urban environments is accelerating due to intensive land use, plastic pollution, construction practices, and climate change, threatening ecosystem stability, food security, and carbon storage capacity. This review synthesizes current advances in biopolymeric materials as regenerative alternatives to conventional soil management approaches. Biopolymers derived from natural sources—including polysaccharides, proteins, and lignin-based compounds—are examined for their multifunctional roles in improving soil structure, enhancing water retention, optimizing nutrient delivery, stabilizing slopes, and supporting pollutant immobilization. Recent developments highlight the emergence of stimuli-responsive hydrogels, controlled-release fertilizer matrices, and composite soil conditioners capable of simultaneously addressing water stress, salinity, erosion, and contamination. In parallel, biodegradable agricultural films and in-soil degradable materials offer pathways to reduce microplastic accumulation while maintaining agronomic performance. Beyond agriculture, bio-based construction materials and bio-receptive design strategies extend biopolymeric interventions into the built environment, promoting soil permeability, microbial diversity, and circular material flows. The review emphasizes the need for context-specific formulation, long-term field validation, and life-cycle assessment to ensure environmental safety and scalability. By integrating soil science, polymer chemistry, and regenerative design, biopolymeric systems are described here as tools for restoring soil health and fostering resilient urban–rural ecosystems under conditions of environmental change. Full article

Graphite remains the predominant negative electrode material in commercial lithium-ion batteries (LIBs); however, its practical performance is increasingly limited by interface-driven degradation rather than bulk intercalation. This review examines the interconnected electrochemical, mechanical, and safety challenges associated with uncoated and coated graphite, with particular focus on how solid electrolyte interphase (SEI) formation and evolution deplete cyclable lithium, increase interfacial resistance, and induce polarization that leads to lithium plating and dendritic growth during rapid charging and low-temperature operation. Electrolyte and solvation engineering are highlighted as coating-free strategies to mitigate these issues by reducing Li⁺ desolvation barriers and directing interphase chemistry toward thinner, more ion-conductive, fluorinated SEI films that inhibit plating while maintaining high-rate capability. Coated graphite approaches are compared, including carbon, inorganic, and polymer coatings that function as artificial SEI layers to minimize direct electrolyte contact, stabilize interphase composition, and enhance mechanical durability. Key trade-offs are discussed, including decreased first-cycle coulombic efficiency (FCCE) due to increased surface area, transport limitations arising from excessively thick coatings, nonuniform coverage leading to local current hotspots, and side reactions induced by the coatings. The discussion is further extended to sodium and potassium systems, explaining how larger ion sizes, unfavorable thermodynamics, and significant lattice expansion hinder their insertion into graphite, and summarizing strategies such as interlayer expansion and alternative carbon architectures that improve reversibility for larger ions. This review concludes that achieving durable, safe, and fast-charging graphite electrodes requires an integrated interfacial design that combines optimized graphite morphology, electrode architecture, and electrolyte chemistry. Full article

In this study, the structure and mechanical properties of composites fabricated by polyetherimide film and powder lamination of carbon fabrics, as well as their impregnation with a polyetherimide/N-methylpyrrolidone solution at different contents, were compared. At compression sintering pressure of 10 MPa, the most uniform structure with the minimum number of discontinuities was formed by film lamination at the maximum carbon fabric content of 70 wt.%. For powder lamination, some discontinuities were found in the composites, which may be caused by the low melt flow index of the polyetherimide powder. The composites fabricated by impregnation with the dissolved PEI possessed low mechanical properties, so the compression sintering pressure was reduced to 6 MPa. After that, an improved composite was characterized by both uniform structure and high mechanical properties (even above those at film lamination), confirming the effectiveness of this fabrication method. Full article

Escherichia coli (E. coli) is a microorganism commonly found in water and food matrices, and its rapid and accurate detection is crucial for maintaining public health and ensuring food safety. However, traditional molecularly imprinted polymer (MIP) sensors often face challenges such as tedious template removal and prolonged sensing times. This study develops a label-free bacterial molecularly imprinted sensor that utilizes the synergistic effect of polypyrrole (PPy) and multi-walled carbon nanotubes (MWCNTs) to achieve highly sensitive detection of E. coli. Based on the large specific surface area and superior conductivity of MWCNTs, as well as the favorable electrochemical polymerization properties of PPy, a PPy/MWCNTs composite film was fabricated via a one-step electropolymerization process. The prepared sensor exhibited excellent kinetic characteristics, with a template removal time of only 15 min, and could be regenerated and used for subsequent detection within 30 min. Under optimized conditions, the biosensor showed a satisfactory linear response over the concentration range of 10²–10⁸ CFU/mL, with a low detection limit of 65 CFU/mL (3σ/S). Furthermore, recovery experiments conducted in tap water and lemon juice samples yielded satisfactory recoveries ranging from 87.1% to 114.8%, demonstrating the reliability and practical applicability of the proposed sensor for bacterial detection in real samples. This sensor offers advantages such as simple preparation, low material cost, and high sensitivity, providing a reliable and practical analytical platform for the rapid and reliable detection of bacteria. Full article

Flexible resistive bend sensors are essential for monitoring human movement in smart rehabilitation and soft robotics. However, widespread adoption is currently hindered by a trade-off between the high cost of metal-film technologies and the performance degradation (significant hysteresis and non-linearity) of low-cost carbon/polymer composites. This study presents a geometrically customizable bending sensor fabricated from conductive thermoplastic polyurethane (TPU) using Fused Deposition Modeling (FDM) technology as an accessible alternative to commercial sensors. By parametrically optimizing physical dimensions—including trace width, layer thickness, and pattern geometry—the sensors were tailored to achieve target resistance values within a target window of 20–50 kΩ (achieved: ~44 kΩ nominal) for specific finger-joint applications. Electromechanical characterization revealed a negative gauge factor (GF), where resistance decreases upon bending or elongation due to conductive pathway formation and densification within the polymer matrix. This behavior cannot affect sensor operation, and required bend-resistance responses were acquired using geometrical optimization. To compensate for inherent viscoelastic-induced hysteresis and non-linear behavior, a third-degree polynomial modeling approach was implemented. This modeling approach yielded a coefficient of determination (R²) of approximately 0.90. Compared to standard commercial sensors, the proposed FDM-printed design successfully overcomes geometric limitations while offering a cost-effective, high-performance solution for tailor-made wearable technologies and smart rehabilitation gloves. Full article

Hydrogen is increasingly adopted as a clean energy carrier for storing and transporting low-carbon energy. Achieving a practical volumetric energy density for real-world deployment typically requires compression to several hundred bar, which in turn demands dedicated high-pressure infrastructure. Because valves are indispensable for isolation and flow control within this infrastructure, durable sealing valve materials become a key reliability and safety requirement. This assembly-level screening study compares two valve configurations with different polymer assemblies: EPDM O-rings with PEEK seats/bushing and NBR O-rings with POM seats/bushing. Four new identical 500-bar ball valves were tested (two EPDM/PEEK and two NBR/POM). For each seal configuration, one valve was cycled 5000 times at 500 bar in helium (inert baseline), and a second identical valve was cycled 5000 times at 500 bar in hydrogen to isolate hydrogen effects from mechanical/metallic wear. Leakage was tracked during cycling, and seals were analyzed by SEM/EDX after testing. The EPDM/PEEK configuration remained leak-tight in both gases, with no cracking observed in the elastomer or thermoplastic components. The NBR/POM configuration exhibited POM bushing fracture during cycling and minor external leakage at the stem during the hydrogen phase, accompanied by micro-fissures on the NBR O-ring surface. EDX indicated composition changes after cycling, including oxygen and fluorine enrichment and occasional metallic transfer species, consistent with surface films and deposits. Under the present valve geometry and cycling protocol, EPDM/PEEK provided robust sealing, whereas NBR/POM showed failure modes relevant to high-pressure service. These findings are intended as configuration-level screening evidence to be used in valves rather than as a full qualification of the individual materials. Full article

Properties of composite materials with polymer matrix and inorganic filler are affected by preparation methods and starting components’ properties. For example, filler powder particle size distribution, phase composition and presence/absence of dopants can greatly affect properties of resulting composites. The present research attempts to clarify the influence of synthetic CaCO₃ powder properties on alginate/CaCO₃ composite material preparation process. Composite materials in the form of granules, networks and films were created from suspensions of synthetic powders of calcium carbonates CaCO₃ in aqueous solutions of sodium alginate. Powders of calcium carbonates CaCO₃ were synthesized from 0.5 M aqueous solutions of calcium chloride CaCl₂ and aqueous solutions of potassium K₂CO₃ (at molar ratio Ca/CO₃ = 1), sodium Na₂CO₃ (at molar ratio Ca/CO₃ = 1), and ammonium (NH₄)₂CO₃ (at molar ratios Ca/CO₃ = 1 and Ca/CO₃ = 0.5) carbonates. Phase composition of powder synthesized from CaCl₂ and K₂CO₃ was presented by calcite. Phase composition of powders synthesized from other soluble carbonates included calcite and vaterite. The powder preparation protocol excluded the stage of synthesized powder washing for by-product removal. This preparation protocol provided preservation of reaction by-product in the synthesized powder at a very low level. The presence of NH₄Cl as a reaction by-product even in small quantities can be taken as a reason for visually observed subsequences of cross-linking reaction at the stage of suspensions preparation. Aqueous solution of sodium alginate and suspensions containing powders synthesized from potassium K₂CO₃ and sodium Na₂CO₃ carbonates demonstrated similar dependence of viscosities from shear rate. The presence of (NH₄)₂CO₃ in the powder synthesized at molar ratio Ca/CO₃ = 0.5 was the reason for the lower viscosity of the suspension in comparison with suspensions loaded with powders containing KCl, NaCl and (NH₄)₂Cl as reaction by-products due to decomposition of unstable (NH₄)₂CO₃ and gas phase formation. The presence of (NH₄)₂Cl in the powder synthesized at molar ratio Ca/CO₃ = 1 in contrast was a reason for the highest viscosity suspension in comparison with those under investigation. Additionally, (NH₄)₂Cl presence in synthetic powders shows the ability to facilitate partial dissolution of CaCO₃ providing a higher concentration of Ca²⁺ cations at the stage of suspension preparation, thus aiding the cross-linking process of alginate hydrogel. Granules, meshes and films were created via interaction of suspensions of calcium carbonates CaCO₃ in aqueous solutions of sodium alginate with 0.25 M aqueous solutions of calcium chloride CaCl₂ to provide the formation of matrix of composites via Ca-crosslinking of sodium alginate followed by washing and freeze drying under deep vacuum. The created composite materials in the form of granules, meshes and films based on Ca-cross-linked alginate and powders of synthetic calcium carbonate can be recommended for skin wound and bone defect treatment and drug delivery carriers. Full article

Thermoplastic carbon fiber-reinforced polymer (CFRP) composites possess the intrinsic capability to heal delamination and matrix cracks via thermal re-melting. However, under impact loading, they are prone to severe fiber fracture, which significantly compromises their repairability. To address this, this study introduced polytetrafluoroethylene (PTFE) films as pre-set interlaminar defects within continuous carbon fiber-reinforced polyamide 6 (CF/PA6) thermoplastic cross-ply laminates. Low-velocity impact tests were conducted at varying energy levels to comparatively investigate the impact response and damage mechanisms of the CFRPs with and without embedded defects. Experimental results indicate that the embedded interlaminar defects triggered a transition in the failure mode of the CFRP from brittle fracture to progressive damage behavior. Compared to the baseline laminates, the specimens with embedded defects maintained higher flexural stiffness under low-energy impact. Furthermore, they effectively reduced the extent of fiber breakage by dissipating impact kinetic energy through extensive delamination, interlaminar frictional sliding, and plastic micro-deformation. These findings verify the feasibility of achieving macroscopic pseudo-ductility through interlaminar microstructural tailoring. This research provides an experimental basis and methodological support for the pseudo-ductile design of thermoplastic composites. Full article

This study investigated the properties of red algae (RA) biocomposite films reinforced with natural sisal fibers and plasticized with glycerol. The polymer was extracted from locally sourced red seaweed and combined sisal fibers at varying fiber loadings (0–45 wt%) using the doctor blading technique. Composite films were analyzed using a variety of methods to evaluate the chemical composition, thermal behavior and mechanical performance. Infrared spectroscopy confirmed the presence of kappa-carrageenan as the dominant polysaccharide in the RA matrix, whereas elemental analysis verified the dilution of sulfur content and enrichment of carbon with increasing fiber incorporation. Thermal stability increased with fiber loading, peaking at 30 wt% sisal fiber before decreasing slightly at 45 wt% due to poor fiber dispersion. Mechanical testing demonstrated an optimal balance between strength and flexibility at 30 wt% sisal fiber, with a 37% increase in strength compared to the pure RA film. Overall, the findings demonstrate that sisal fiber reinforcement enhances the structural integrity and stability of RA-based films, supporting their potential as biodegradable alternatives to petroleum-based plastics. Full article

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. Full article

Nanocellulose, a biodegradable and renewable nanomaterial derived from biomass, has emerged as a promising sustainable building block for flexible functional devices due to its renewability, low density, excellent mechanical strength, tunable surface chemistry, and outstanding film-forming capability. This paper provides a critical review of the evaluations and synthesis of recent progress in the manufacturing, functionalization, and incorporation of nanocellulose and its composite materials for electronic devices and electrical systems applications. The paper also highlights the contributions of nanocellulose to performance, durability, and environmental sustainability, along with its potential uses in flexible electrical equipment, energy storage devices, sensors, and conductive components. Furthermore, the review examines the combined effects of nanocellulose with metallic nanoparticles, carbon-based materials, and polymers in developing superior electrically conductive composites. In addition, the article highlights research gaps and suggests future directions for advancing sustainable, high-performance conductive materials. Finally, the paper critically analyzes key challenges such as reliability, interface compatibility, and long-term stability, and proposes strategies to address these limitations. Full article

Herein, we propose a simple and cost-effective method for fabricating moderate-sensitivity surface-enhanced Raman scattering (SERS) substrates using Cu-plasma polymer fluorocarbon (Cu-PPFC) nanocomposite films fabricated through RF sputtering. The use of a composite target composed of carbon nanotube (CNT), Cu, and polytetrafluoroethylene (PTFE) powders (5:60–80:35–15 wt%) offers the advantage of the simple fabrication of moderate-sensitivity SERS substrates with a single cathode compared to co-sputtering. X-ray photoelectron spectroscopy (XPS) revealed that the film surface was partially composed of metallic Cu with Cu-F bonds and Cu–O bonds, confirming the coexistence of the conducting and plasmon-active domains. UV-VIS spectroscopy revealed a distinct absorption peak at approximately 680 nm, indicating the excitation of localized surface plasmon resonances in the Cu nanoclusters embedded in the plasma polymer fluorocarbon (PPFC) matrix. Atomic force microscopy and grazing incidence small-angle X-ray scattering analyses confirmed that the Cu nanoparticles were uniformly distributed with interparticle distances of 20–35 nm. The Cu-PPFC nanocomposite film with the highest Cu content (80 wt%) exhibited a Raman enhancement factor of 2.18 × 10⁴ for rhodamine 6G, demonstrating its potential as a moderate-sensitivity SERS substrate. Finite-difference time-domain (FDTD) simulations confirmed the strong electromagnetic field localization at the Cu-Cu nanogaps separated by the PPFC matrix, corroborating the experimentally observed SERS enhancement. These results suggest that a Cu-PPFC nanocomposite film, easily fabricated using a composite target, provides an efficient and scalable route for fabricating reproducible, inexpensive, and moderate-sensitivity SERS substrates suitable for practical sensing applications. Full article

The advancement of smart packaging technology demands high-performance and sustainable sensing materials. While starch is a biodegradable natural polymer, its inherent high crystallinity restricts charge transport capability. This study developed a novel smart sensing film by incorporating ellagic acid-derived blue, fluorescent carbon dots (CDs) into phosphate starch (PS), which is rich in phosphorus. The effects of silver ions (Ag⁺), sodium carboxymethyl cellulose (CMC), and CDs on the film properties were systematically investigated. Results indicate that CDs act as flexible nano-crosslinkers, forming hydrogen bonds with PS molecular chains and effectively balancing strength and toughness—achieving a tensile strength of 5.1 MPa and an elongation at break of 24.1%. Phosphorus, in synergy with CDs, facilitates an efficient dual conduction pathway for ions and electrons: phosphate groups enable ion transport, while the conjugated carbon cores of the CDs provide electron transport channels. This synergistic effect significantly reduces the film’s electrical impedance from 6.93 × 10⁶ Ω to 1.12 × 10⁶ Ω (a reduction of 84%) and enhances thermal stability, increasing the char residue from 1.1% to 18.3%. The PS/CDs composite film exhibits a strong linear current response to pH in the range of 2–7 (R² = 0.9450), and shows enhanced discrimination between fresh orange juice (pH = 3.38) and spoiled orange juice (pH = 2.68), with a current change of 0.62 × 10⁻⁵ A. Moreover, the film exhibits strong blue fluorescence at 427 nm, with an intensity that shows a pronounced pH-dependent response. This study elucidates the mechanism by which phosphorus and CDs synergistically enhance the sensing performance of starch-based films, offering a new strategy for developing high-performance starch-based materials for smart packaging. Full article

The market for bioactive compounds of natural origin has expanded greatly over the past few years. These compounds can be found as individual supplements or food additives. Due to the importance of this market, incorrect data on their composition can often be found. Therefore, monitoring their concentration is of great importance. Although there are various methods for their selective and sensitive determination, electrochemical sensors represent an important tool in this field. With the development of nanotechnology, additional importance has been given to these sensors. Strictly controlled synthesis procedures can yield nanomaterials with unique morphological properties and significantly improved electrocatalytic capabilities. The integration of two or more nanomaterials in the form of a nanocomposite and/or nanohybrids allows for the synergistic effect of each of the components. Thus, excellent final characteristics are obtained in the field of electrochemical sensors, such as improved sensor stability, selectivity, and lower detection limits. In recent years, various forms of carbon nanomaterials, polymer films, metal and metal oxide nanoparticles (or simply metal/metal oxide nanoparticles), MOFs, porous nanomaterials, MXenes, and others with clearly defined characteristics represent an important step forward in this field. Carefully prepared, these materials achieve strong interactions with selected analytes, which results in significant progress in analytical methods for monitoring biologically active compounds. Therefore, this review summarizes the latest trends in this field, focusing on the method of material preparation, final morphology and electrocatalytic properties, selectivity, and sensitivity. Conclusions and expected future directions in this field are also given in order to improve current analytical performance. Full article