Search Results (89)

This study presents the development of biocompatible antistatic nanofibrous composite yarns via a scalable AC electrospinning method, incorporating ultrasonicated expanded graphite (uEG) and PEDOT:PSS into polyamide (PA), polyvinyl butyral (PVB), and polyvinyl alcohol (PVA) matrices. TGA confirmed high filler retention during electrospinning. Electrical measurements showed that the addition of uEG and micrographite reduced single-yarn resistance by up to two orders of magnitude compared with neat polymers, yielding normalised resistivities as low as ~10⁵–10⁶ Ω·m and conductivities in the 10⁻⁷–10⁻⁵ S/m range, suitable for antistatic and sensing applications. However, the large filler–fibre size mismatch and highly porous yarn architecture limited the formation of continuous conductive networks, and mechanical tests revealed strength reductions of up to 70–80% at the highest PVB filler loadings. XRD confirmed a reduction in crystallinity with filler addition, PEDOT:PSS enhanced polymer chain nucleation and thus mechanical properties. Cytotoxicity assays demonstrated that uEG, micrographite, and PEDOT:PSS significantly improved cell viability compared with non-crosslinked PVA, with several PVB-based and PVA/uEG composites showing viability statistically comparable to the DMEM control (>70%) while remaining significantly higher than the Triton positive control. Overall, this work establishes an AC-electrospun route to antistatic nanofibrous yarns that combine high filler retention with enhanced biocompatibility. Full article

Annealing is a critical step in the fabrication of soft magnetic composites (SMCs), and precise coordination of annealing atmosphere and temperature is essential for optimizing their performance. In this study, FeSiCr SMCs were annealed under three different atmospheres (air, nitrogen, and argon) across a range of temperatures, and the effects of the annealing atmosphere on their microstructure and soft magnetic properties were systematically investigated. The results demonstrate that annealing in an inert atmosphere, particularly argon, within the temperature range of 450–750 °C, yields superior magnetic properties compared with air annealing. After annealing under argon at 550 °C, the effective magnetic permeability (μ_e) reached 47.5, and the power loss (P_cv) was 1457.3 kW/m³ at 1000 kHz and 30 mT. These improvements are primarily attributed to effective stress relaxation and the substantial retention of the polyvinyl butyral (PVB) insulating layer. With further increases in annealing temperature, the magnetic properties deteriorate rapidly due to the complete decomposition of PVB and the formation of conductive chromium carbides. Under such conditions, air annealing exhibits distinct advantages. Selective oxidation of FeSiCr occurs, leading to the formation of a dense chromium oxide insulating layer that enhances magnetic performance (after annealing at 850 °C, μ_e = 47.9, P_cv = 1632.0 kW/m³). Moreover, the mechanical properties were significantly improved, with the radial crush strength increasing from 22.36 N in the unannealed state to 330 N after annealing. These results indicate that the comprehensive performance of SMCs can be effectively tailored through the appropriate selection of annealing atmosphere and temperature, providing valuable guidance for the design and optimization of high-performance SMCs. Full article

To reduce food waste and mitigate health risks from accidentally consuming spoiled food, freshness-indicating technologies are increasingly demanded. However, conventional colorimetric-based freshness-indicating packaging is limited by instability, subtle color changes, and complex production processes. This study presents a curcumin-based ink suitable for eco-friendly polylactic acid (PLA) food packaging films enabling real-time shrimp freshness monitoring via integrated intelligent packaging. The ink comprised curcumin as the indicator, ethyl cellulose (EC) and polyvinyl butyral (PVB) as binders, and polyethylene glycol 400 (PEG 400) to regulate permeability. Excellent printability was demonstrated by fineness, initial dryness and fluidity tests. It also demonstrated good thixotropic, viscosity, and flow curve properties. Printing minimally affected the PLA films’ mechanical and barrier properties. The indicator label showed high sensitivity, rapid response, and excellent reversibility to ammonia vapor. Practical application in monitoring shrimp spoilage at 25 °C and 4 °C revealed a strong correlation between the distinct color transition of the label and the increase in total volatile basic nitrogen (TVB-N) content and pH value, providing a reliable visual warning before obvious spoilage signs appeared. This work provides a viable integrated indicator packaging strategy for developing intelligent packaging, offering significant potential to reduce food waste and enhance supply chain transparency for perishable goods. Full article

Injection molding has been used for many years in the fabrication of thermoplastic parts with different complexities. With metal and ceramic injection molding, it is possible to realize at the end of the related process chain sintered metal and ceramic parts. Parts made from glass are rather seldom realized applying powder technology methods. This work describes the production of devices made from a commercial soda-lime glass applying the process chain of powder injection molding, covering the individual process steps like compounding, shaping, debinding, and sintering. In the first step, a binder consisting of polyethylene glycol (PEG) with different average molecular masses (4000, 8000, and 20,000 g/mol), polyvinyl butyral (PVB), and stearic acid (SA) were used for compounding new feedstocks with a solid load of 55 Vol% and 60 Vol%. As filler, a soda-lime glass with an average particle size of 6.1 µm, an almost symmetrical particle size distribution, a specific surface area of 0.78 m²/g, and a spherical morphology was applied. The measured equilibrium torque during compounding was low, with values between 2.5 and 5.5 Nm depending on the solid load and average molecular mass of the investigated PEG. All feedstock possessed a pseudoplastic flow behavior in the shear rate range between 10 and 3500 1/s. Small disk-shaped parts, as well as large cuboids and plates, were injection molded to a good quality. These green bodies were pre-debinded in water to remove the PEG, subsequently followed by thermal debinding to eliminate the remaining organic moieties. The concluding sintering in the temperature range between 660 and 680 °C delivered glass parts with huge density values close to 100% of the theoretical value, as measured by the Archimedes method. The principal feasibility of glass injection molding with a suitable feedstock system could be demonstrated successfully. Full article

Poly(vinyl butyral) (PVB) displays exceptional adhesion to glass surfaces and high transparency, serving as the dominant interlayer material in laminated glass composites. This study systematically investigates PVB particulate composites, focusing on the interactions between a plasticized PVB matrix and silicate or silica dispersions as reinforcements. PVB composites reinforced with glass flakes, glass fibers, and fumed silica at loadings of 2, 5, and 8 vol% were produced and characterized. Optical microscopy and thermogravimetric analysis were employed to evaluate filler incorporation and dispersion under melt mixing conditions representative of industrial extrusion. Transparency measurements assessed the optical clarity of the composites, while ATR-FTIR was used to identify chemical interactions between PVB and the fillers. Regarding mechanical performance, fumed silica increased tensile strength up to 29 MPa and reduced displacement at fracture by 120%, while high-aspect-ratio flakes and silane-treated fibers only significantly increased composite stiffness. Impact resistance was additionally evaluated, revealing a significant enhancement upon the addition of fibrous reinforcements, especially when silane-treated fibers were used. Fumed silica increased the thermal stability of PVB by 7 °C and reduced water uptake to approximately 4.5%, in contrast to glass flakes, which increased water absorption reaching up to 8–11%. Lastly, the processability of composites was monitored, showing a progressive decrease with increasing filler content for all reinforcements. Overall, this work provides a comprehensive assessment of PVB–silicate/silica interfacial interactions and highlights the design of PVB composites suitable for advanced applications or the upcycling of secondary recycled PVB grades. Full article

To address the low-value recycling dilemma of waste polyvinyl butyral (PVB) and cater to the demand for sustainable multifunctional active food packaging, this study developed a facile and cost-effective solution blow spinning approach. Continuous, smooth, and bead-free nanofiber membranes were prepared by optimizing the solution blow spinning process parameters. Zinc oxide nanoparticles (ZnO NPs) were incorporated into the PVB nanofiber membrane with vacuum impregnation. The results demonstrated that ZnO NPs significantly enhanced the tensile strength, thermal stability, and the UV absorption of PVB fiber membranes. ZnO/PVB fiber membranes exhibited antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Practical preservation tests showed that ZnO/PVB fiber membranes effectively inhibited cherry tomatoes’ microbial spoilage and water loss, extending the shelf life of tomatoes to 13 days. These findings validate the potential of ZnO/PVB composite nanofiber membranes as active food packaging and provide a feasible technical pathway for the low-cost, efficient utilization of recycled PVB. Full article

Poly(lactic acid) (PLA) has strong potential for use in sustainable packaging, automotive components, and structural materials; however, its inherent brittleness and limited thermal stability restrict broader application. To overcome these drawbacks, this study developed PLA-based composites reinforced with mica and compatibilized using poly(vinyl butyral) (PVB). To overcome the inherent brittleness and limited thermal stability of poly(lactic acid) (PLA), this study investigated the incorporation of mica as a reinforcing filler into PLA and PLA/poly(vinyl butyral) (PVB) composite systems. Five types of mica with varying particle sizes and densities were examined to evaluate their influence on the mechanical, thermal, and rheological properties of the composites. The PLA/PVB blend was prepared in an 8:2 weight ratio, and mica was added at 5 phr (35 g). PLA/mica composites showed limited improvement in mechanical performance due to poor interfacial compatibility between PLA and mica, resulting in decreased tensile strength and non-uniform filler dispersion. In contrast, the addition of PVB, a tough and flexible polymer containing hydroxyl groups (ca. 20 mol%) remaining after polymerization, significantly enhanced the interfacial interaction with mica and improved filler dispersion within the matrix. As a result, PLA/PVB/mica composites exhibited increased tensile strength and toughness. Thermal analysis revealed that mica restricted polymer chain mobility, leading to higher glass transition temperatures, while PVB promoted a more uniform crystalline structure. Rheological studies indicated that PLA/PVB/mica composites had higher complex viscosity and lower melt flow index (MFI) due to increased molecular interactions and reduced chain mobility. Notably, certain mica types containing Ca²⁺ ions catalyzed chain scission during melt processing, leading to reduced molecular weight and increased MFI. These findings demonstrate that the synergistic combination of PVB and mica can effectively improve the processability and performance of PLA-based composites, offering a promising route for developing sustainable materials for advanced applications. Full article

The assessment of the dynamic mechanical performance of fiber-reinforced composites has gained importance in specific high-tech applications like aerospace and automobiles. However, three dimensional (3D) auxetic reinforcements offering viable performance have remained unexplored. Hence, this study investigates the energy absorption capabilities and high strain impact behaviors of 3D woven fabric-reinforced composites. Three different types of 3D woven reinforcements i.e., warp interlock (Wp), weft interlock (Wt), and bidirectional interlock (Bi) were developed from jute yarn, and their corresponding composites were fabricated using polycarbonate (PC) and polyvinyl butyral (PVB). Out-of-plane auxeticity was measured for reinforcements while composites were analyzed under dynamic tests. Wp exhibited the highest auxeticity with a value of −1.29, Bi showed the least auxeticity with a value of −0.31, while Wt entailed an intermediate value of −0.46 owing to variable interlacement patterns. The dynamic mechanical analysis (DMA) results revealed that composite samples developed with PC resin showed a higher storage modulus with the least tan delta values less than 0.2, while PVB-based samples exhibited higher loss modulus with tan delta values of 0.6. Split Hopkinson pressure bar (SHPB) results showed that, under 2 and 4 bar pressure tests, PVB-based composites exhibited the highest maximum load while PC-based composites exhibited the least. Warp interlock-based composites with higher auxeticity showed better energy absorption when compared with the bidirectional interlock reinforcement based (with lower auxeticity) composites that exhibited lower peak load and energy dissipation. Full article

This study presents a comprehensive investigation into the large-scale production of synthetic and hybrid (nanoparticle-loaded) nanofibers using needleless electrospinning. A diverse range of polymers, including polyamide 6 (PA6) and its other polymer combinations, recycled PA6, polyamide 11 (PA11), polyamide 12 (PA12), polyvinyl butyral (PVB), polycaprolactone (PCL), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyurethane (PU), polyvinyl alcohol (PVA), and cellulose acetate (CA), were utilized to fabricate nanofibers with tailored properties such as polymer solution concentrations and various solvent systems. Furthermore, an extensive variety of nano- and micro-particles, including TiO₂, ZnO, MgO, CuO, Ag, graphene oxide, CeO₂, Er₂O₃, WO₃, MnO₂, and hyperbranched polymers, were incorporated into the polymeric systems to engineer multifunctional nanofibers with enhanced structural characteristics. The study examines the impact of polymer–nano/micro-particle interactions, fiber morphology, and the feasibility of large-scale production via needleless electrospinning. The resulting nanofibers exhibited diameters starting from 80 nm, depending on the polymer and processing conditions. The incorporation of TiO₂, CeO₂, WO₃, Ag, and ZnO nanoparticles into 15% PA6 solutions yielded well-dispersed hybrid nanofibers. By providing insights into polymer selection, nano- and micro-particle integration, and large-scale production techniques, this work establishes a versatile platform for scalable hybrid nanofiber fabrication, paving the way for innovative applications in nanotechnology and materials science. Full article

This study investigates the elastoplastic behavior of phenol formaldehyde/polyvinyl butyral matrix (70% PF/30% PVB) reinforced with Kevlar^® fibers through comprehensive in-plane tensile testing. Cyclic loading–unloading tests were conducted at a 100%/min strain rate using a universal testing system at room temperature on $\left(0_4\right)$, $\left({90}_4\right)$, and ${\left(\pm 45\right)}_s$ laminates. The experimental results revealed significant nonlinear hardening behavior beyond yield stress, accompanied by yarn stiffening effects during loading cycles. A novel elastoplastic constitutive model was developed, incorporating Hill’s yield criterion adapted for orthotropic materials and an isotropic hardening function that accounts for equivalent plastic strains and progressive yarn stiffening. Laminates with other stacking sequences were also tested and the accuracy of the predictions of the nonlinear behavior was assessed. In these laminates, delaminations took place and the model provided an overestimation of the stress–strain response. Since the model could not predict delamination onset and propagation, an adaptation of the model considering fully delaminated interfaces brought a lower bound of this response. Despite the limitations of the model, it can be used to provide reasonable limits to the stress–strain response of laminates accounting for plastic strains within plies. This study provides essential mechanical properties and constitutive relationships for designing Kevlar^® composite structures with tailored stiffness characteristics for impact-resistant applications. Full article

This study introduces and validates a comparative experiment-based method for determining the effective thickness of composite glass, including polymeric laminated glass (with polyvinyl butyral (PVB) and SentryGlas^® (SGP) interlayers) and vacuum glazing. This method employs comparative four-point bending tests, defining effective thickness by equating the bending stress of a composite specimen to that of a reference monolithic glass specimen under identical loading and boundary conditions. Specimens with varying configurations (glass thicknesses of 5 mm, 6 mm and 8 mm) were tested using non-destructive four-point bending tests under a multi-stage loading protocol (100 N–1000 N). Strain rosettes measured maximum strains at each loading stage to calculate bending stress. Analysis of the bending stress state revealed that vacuum glazing and SGP laminated glass exhibit superior load-bearing capacity compared to PVB laminated glass. The proposed method successfully determined the effective thickness for both laminated glass and vacuum glazing. Furthermore, results demonstrate that employing a 12 mm monolithic reference glass provides the highest accuracy for effective thickness determination. Theoretical bending stress calculations using the effective thickness derived from the 12 mm reference glass showed less than 10% deviation from experimental values. Conversely, compared to established standards and empirical formulas, the proposed method offers superior accuracy, particularly for vacuum glazing. Additionally, the mechanical properties of the viscoelastic interlayers (PVB and SGP) were investigated through static tensile tests and dynamic thermomechanical analysis (DMA). Distinct tensile behaviors and differing time-dependent shear transfer capacities between the two interlayer materials are found out. Key factors influencing the reliability of the method are also discussed and analyzed. This study provides a universally practical and applicable solution for accurate and effective thickness estimation in composite glass design. Full article

The dielectric relaxation behavior of polymeric materials is critical to their performance in electronic, insulating, and energy storage applications. This study presents an electrical fractional model (EFM) based on fractional calculus and the complex electric modulus ($M^{*}\mathit{=}{M}^{\prime }\mathit{+}i{M}^{″}$) formalism to simultaneously describe two key relaxation phenomena: $\alpha$-relaxation and interfacial polarization (Maxwell–Wagner–Sillars effect). The model incorporates fractional elements (cap-resistors) into a modified Debye equivalent circuit to capture polymer dynamics and energy dissipation. Fractional differential equations are derived, with fractional orders taking values between 0 and 1; the frequency and temperature responses are analyzed using Fourier transform. Two temperature-dependent behaviors are considered: the Matsuoka model, applied to $\alpha$-relaxation near the glass transition, and an Arrhenius-type equation, used to describe interfacial polarization associated with thermally activated charge transport. The proposed model is validated using literature data for amorphous polymers, polyetherimide (PEI), polyvinyl chloride (PVC), and polyvinyl butyral (PVB), successfully fitting dielectric spectra and extracting meaningful physical parameters. The results demonstrate that the EFM is a robust and versatile tool for modeling complex dielectric relaxation in polymeric systems, offering improved interpretability over classical integer-order models. This approach enhances understanding of coupled relaxation mechanisms and may support the design of advanced polymer-based materials with tailored dielectric properties. Full article

Additive manufacturing (AM), particularly fused deposition modeling (FDM) 3D printing, has emerged as a versatile and accessible technology for prototyping and functional part production across a wide range of industrial applications. One of the critical performance-limiting factors in AM is the chemical resistance of thermoplastic materials, which directly influences their structural integrity, durability, and suitability in chemically aggressive environments. This study systematically investigates the chemical resistance of eight different widely utilized FDM filaments—acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polyamide (PA, Nylon), polycarbonate (PC), polyethylene terephthalate glycol (PETG), polylactic acid (PLA), polypropylene (PP), and polyvinyl butyral (PVB)—by examining their tensile strength and impact resistance after immersion in representative chemical agents: distilled water, ethanol (99.5%), isopropyl alcohol (75% and 99%), acetic acid (8%), hydrochloric acid (37%), hydrogen peroxide (30%), and acetone (99.5%). Quantitative mechanical testing was conducted in accordance with ASTM D638 and ASTM D256 standards, and statistical variability was accounted for using triplicate measurements with standard deviation analysis. The results reveal that PP exhibits the highest chemical resilience, retaining over 97% of its mechanical properties even after 7 days of immersion in aggressive solvents like acetone. PETG and ASA also demonstrated quite successful stability (>90% retention) in mildly corrosive environments such as alcohols and weak acids. In contrast, PLA, due to its low crystallinity and polar ester backbone, and PVB, due to its high amorphous content, showed substantial degradation: tensile strength losses exceeding 70% and impact resistance dropping below 20% in acetone. Moderate resistance was observed in ABS and PC, which maintained structural properties in neutral or weakly reactive conditions but suffered mechanical deterioration (>50% loss) in solvent-rich media. A strong correlation (r > 0.95) between tensile and impact strength reduction was found for most materials, indicating that chemical attack affects both static and dynamic mechanical performance uniformly. The findings of this study provide a robust framework for selecting appropriate 3D printing materials in applications exposed to solvents, acids, or oxidizing agents. PP is recommended for harsh chemical environments; PETG and ASA are suitable for moderate exposure scenarios, whereas PLA and PVB should be limited to low-risk, esthetic, or disposable applications. Full article

This investigation of hydroxyl and polysiloxane absorption peaks in elastic polymer composites reveals significant spectral shifts within the fingerprint region of FTIR spectra. Using poly(vinyl butyral) (PVB) as the base polymer and poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA) as reference materials, solvent effects on polymer–solvent interactions were systematically analyzed. Among the tested alcohol solvents, PEG 400 induced the most pronounced spectral changes, with the C=O stretching band shifting from 1740 to 1732 cm⁻¹ and the O–H band significantly broadening and downshifting to around 3300 cm⁻¹, reflecting strong hydrogen-bonding interactions. Wavelet-based noise reduction effectively enhanced the signal-to-noise ratio, reducing the baseline standard deviation by over 90%. This study introduces a novel noise-enhanced FTIR recognition model that integrates baseline noise metrics to improve detection sensitivity. The model successfully uncovers subtle structural variations in polymer–solvent systems that are typically masked by conventional FTIR techniques, advancing materials analysis and providing a robust framework for future FTIR-based diagnostics and material characterization. Full article

High-density polyethylene (HDPE) is a widely used thermoplastic known for its chemical resistance and ease of processing, but it has limited wear performance and moderate mechanical properties. In this study, recycled polyvinyl butyral (rPVB) was incorporated into HDPE at 5, 10, 15, and 20 wt.% to evaluate its effect on tribological performance. Pin-on-disk wear tests were conducted at 12, 15, and 18 N to assess the coefficient of friction (CoF) and wear resistance. Mean CoF values decreased by up to 40% with rPVB addition, with the best performance observed at 15 wt.% rPVB, although some variation was observed across replicates. SEM analysis revealed that rPVB promotes finer debris and transfer film formation, explaining the CoF reduction. However, wear resistance exhibited a complex trend: while rPVB improved adhesion and reduced material loss at lower loads, volume loss increased at higher loads, likely due to rPVB’s lower hardness. Mechanical testing showed an increase in elastic modulus at low rPVB contents due to higher crystallinity, confirmed by DSC; however, tensile strength and impact resistance decreased with rPVB. The results suggest that incorporating 10–15 wt.% of rPVB into HDPE can enhance frictional performance without severely compromising mechanical integrity, offering a sustainable way to valorize rPVB. Full article