Search Results (406)

Background/Objectives: Wound healing requires simultaneous pain control, inflammation management, infection prevention, and tissue regeneration. This study aimed to develop and evaluate in vitro a non-contact thermosensitive spray hydrogel combining lidocaine for rapid analgesia and allantoin for tissue repair. Methods: The effects of chitosan and Poloxamer 407 on viscosity, spray diameter, and bioadhesion ability of hydrogels were optimized using response surface methodology. Lead formulations (S1 and S2) were selected via a desirability function within the software. The pH, gelation temperature (T_G), rheological behavior, sprayability, bioadhesion, and lidocaine release using the dialysis bag method were assessed. The in vitro cytotoxicity, anti-inflammatory activity (TNF-α), and cell migration (scratch assay) of the formulations were investigated. Results: The viscosity values (42.7–58.7 mPa·s) indicated suitability for spraying at room temperature. T_G was 28.7 ± 0.6 °C (S1) and 29.3 ± 0.3 °C (S2), enabling rapid sol–gel transition at skin temperature. The lidocaine release reached 95–100% within 120 min. S2 exhibited lower viscosity and wider spray diameter, improving applicability on larger wound areas. In vitro cytotoxicity, scratch assay, and inflammatory marker analyses demonstrated that the optimized sprayable hydrogels exhibited a biocompatible and cell-healing profile. Conclusions: The developed thermosensitive spray hydrogel enables the combined delivery of lidocaine and allantoin, rapid gelation at body temperature, and touch-free administration. Its suitable viscosity and sprayability, and fast lidocaine release profile indicate high patient compliance and a significant advantage over conventional cream/ointment formulations, particularly regarding painless application, reduced contamination risk, enhanced therapeutic potential, and confirmed in vitro biocompatibility with supportive effects on keratinocyte behavior. Full article

Based on hot-compression simulations combined with SEM and TEM analyses, the high-temperature deformation behavior and mechanisms of a new nickel-based powder superalloy FGH101 were investigated over 1020–1110 °C and strain rates of 0.001–0.05 s⁻¹. From the experimental data, the variations in the strain-rate sensitivity index m, the apparent activation energy for hot deformation Q, and the grain-size exponent p were determined as functions of strain rate and temperature. Hot deformation processing maps and mechanism maps incorporating dislocation density were established. The processing maps clearly revealed the evolution of formable regions at different temperatures and strains, while the mechanism maps successfully predicted the dislocation evolution and its operative hot deformation mechanisms by introducing the grain size evolution corrected by Burgers-vector compensation and the rheological flow stress behavior compensated by the modulus. The results indicated an optimal processing window of 1060–1100 °C at 0.001–0.003 s⁻¹. Within the tested regime, as the strain rate decreased, the operative mechanism for grain-boundary sliding transitioned from pipe-diffusion control to lattice-diffusion control. These findings provide a solid theoretical basis for the design and optimization of the isothermal forging process of the new FGH101 alloy. Full article

This study investigates the influence of dynamic perturbation on gelation behavior in a model colloidal system composed of hydrophobic silica particles dispersed in dioctyl phthalate. Contrary to the prevailing assumption that gelation is independent of oscillatory frequency, particularly at small strain amplitudes within the linear viscoelastic regime, our results reveal a pronounced dependence of gelation dynamics on the frequency of applied shear. In contrast, variations in strain amplitude and shear rate amplitude exert minimal effects. This observed behavior deviates significantly from classical gelation theory, which typically predicts frequency-independent rheological properties at the gel point. The results uncover a previously unrecognized viscoelastic phenomenon in soft colloidal materials, wherein microstructural rearrangements near the gelation threshold appear to be modulated by the timescale of mechanical excitation. As a result, traditional criteria for identifying gelation become less effective. The liquid-to-solid transition in these colloidal systems aligns more closely with the physics of particle jamming, rather than polymer network formation. Full article

A series of high-viscosity ferrofluids with variations in particle concentration and carrier liquid molecular weight were synthesized in a fluoroether oil base by the chemical coprecipitation method. The microstructure, surface coating, and magnetic properties of the nanoparticles were characterized, and the rheological properties of the corresponding ferrofluids were systematically investigated to elucidate their governing mechanisms and underlying mechanisms. The results indicate that the synthesized zinc-doped ferrite particles are spherical with a size of less than 50 nm and are chemically coated with a fluoroether acid. Moreover, the saturation magnetization of the ferrofluids increases with rising particle concentration. With the increase in particle concentration, the zero-field viscosity and shear stress of the ferrofluids increase significantly. The zero-field viscosity and shear yield stress of the ferrofluid increase significantly with the molecular weight of the carrier liquid, due to the strengthened entanglement of its molecular chains. At a carrier liquid molecular weight of 4600 g/mol, the 50 wt.% ferrofluid displayed a liquid character, in contrast to the gel-like character displayed by the 60 and 70 wt.% samples. The 60 wt.%-7480 g/mol sample demonstrated superior elasticity to its 60 wt.%-4600 g/mol counterpart. Furthermore, the application of a 100 mT magnetic field induced a transition from a liquid to a gel state in the 50 wt.%-4600 g/mol sample. This transition, driven by the formation of magnetic field-induced chain-like structures, significantly enhanced the magnetoviscous effect. This study provides the theoretical basis and experimental support for the development of high-viscosity ferrofluid sealing materials suitable for high-pressure, liquid environments and corrosive working conditions. Full article

Additive manufacturing (AM) with clay and ceramic-based materials is gaining momentum as a sustainable alternative in construction, yet its advancement depends on bridging experimental practice with predictive modeling. This review synthesizes advances in mathematical formulations and numerical tools applied to clay, geopolymers, alumina, and related extrusion-based pastes. Classical rheological models, including the Bingham and Herschel–Bulkley formulations, remain central for characterizing yield stress, structuration, and flow stability. Meanwhile, finite element (FEM) and computational fluid dynamics (CFD) approaches are increasingly supporting predictions of deformation, shrinkage, drying, and sintering. Despite these advances, their application to natural clay systems remains limited due to heterogeneity, moisture sensitivity, and the lack of standardized constitutive parameters. Recent studies emphasize that validation is essential: rheometry, layer stability tests, in situ monitoring, and prototyping provide necessary calibration for reliable simulation. In parallel, parametric and generative design workflows, particularly through Rhino and Grasshopper ecosystems, illustrate how digital methods can link geometric logic, fabrication constraints, and performance criteria. Overall, the literature demonstrates a transition from isolated modeling efforts toward integrated, iterative frameworks where rheology, numerical simulation, and experimental validation converge to improve predictability, reduce trial-and-error, and advance scalable and sustainable clay- and ceramic-based AM. Full article

The generation and stability of foam are critical attributes influencing the perceived efficacy and sensory experience of cleansing products like face cleansers and hair shampoos. This study rigorously investigated the influence of water hardness on the foam characteristics of a face cleanser and hair shampoo through integrated macroscopic, microscopic, and rheological analyses. Hard water consistently induced severe foam destabilization, evidenced by significantly increased foam decay and shortened drainage half-lives. Microstructural analysis revealed pronounced bubble coalescence, manifested as reduced bubble counts and elevated mean bubble areas. Rheologically, hard water compromised foam viscoelasticity, leading to diminished complex moduli (G*), earlier G″/G′ crossovers, and heightened phase angles (δ), signifying a rapid transition to a predominantly viscous, unstable state. Conversely, soft water consistently yielded highly elastic foams with robust G* values, maintained G′ dominance, and low δ, indicative of superior structural integrity and temporal stability. Notably, controlled rate viscosity profiles remained unaffected by water hardness. These findings collectively demonstrate that divalent cations fundamentally undermine foam lamellar film stability, inducing profound structural and mechanical degradation. Concurrently, tribological measurements revealed that the face cleanser consistently exhibited higher coefficients of friction in hard water across varying sliding speeds, whereas the hair shampoo displayed a more complex, speed-dependent frictional profile that was comparatively less sensitive to water hardness. This underscores the critical necessity for formulation chemists to mitigate water hardness effects to ensure consistent product performance and sensory attributes. Full article

The irrigation sector urgently needs more eco-sustainable materials able to guarantee the same performance as traditional fittings manufactured from virgin fossil-based polymers. In this study, sustainable composites were developed by melt-compounding virgin and recycled polypropylene (RPP) with hazelnut shell (HS) powder with or without maleic-anhydride-grafted polypropylene (PPC) coupling agent. The materials were characterized by a rheological and mechanical point of view. At high shear rates, the viscosity curves of matrices and composites converge, making the difference between neat and filled systems negligible in terms of processability. This indicates that standard injection-molding parameters used for the neat matrices can also be applied to the composites without significant adjustments. Tensile tests showed that adding 10 wt% HS powder increased the elastic modulus by approximately 30% (from 960 MPa to 1.2 GPa) while reducing elongation at break by about 90% compared with neat RPP. The use of PPC mitigated this loss of ductility, partially restoring tensile strength and increasing EB from 6% to 18% in RPP-based composites (+200%). Finally, sleeve bodies and nuts injection-molded from RPP/HS5 and RPP/HS5/PPC successfully resisted internal water pressure up to 3.5 bar without leakage or structural damage. These findings demonstrate that agro-industrial waste can be effectively valorized as a functional filler in recycled polypropylene, enabling the manufacture of irrigation fittings with mechanical and processing performances comparable to those of virgin PP and supporting the transition toward a circular economy. Full article

The design of sustainable polymer systems with tunable properties is essential for next-generation functional materials. This study examines the influence of a phenol-free modified rosin resin (Unik Print™ 3340, UP)—a maleic anhydride- and fumaric acid-modified gum rosin—on the structural, thermal, rheological, and mechanical behavior of four poly(lactic acid) (PLA) grades with different molecular weights and crystallinity. Blends containing 3 phr of UP were prepared by melt compounding. Thermogravimetric analysis showed that the incorporation of UP did not alter the thermal degradation of PLA, confirming stability retention. In contrast, differential scanning calorimetry revealed that UP affected thermal transitions, suppressing crystallization and melting in amorphous PLA grades and shifting the crystallization temperature to lower values in semi-crystalline grades. The degree of crystallinity decreased for low-molecular-weight semi-crystalline PLA but slightly increased in higher-molecular-weight samples. Mechanical tests indicated that UP acted as a physical modifier, increasing toughness by over 25% for all PLA grades and up to 60% in the amorphous, low-molecular-weight grade. Rheological measurements revealed moderate viscosity variations, while FESEM analysis confirmed microstructural features consistent with improved ductility. Overall, UP resin enables fine tuning of the structure–property relationships of PLA without compromising stability, offering a sustainable route for developing bio-based polymer systems with enhanced mechanical performance and potential use in future biomimetic material designs. Full article

The growing need for effective antimicrobial polymeric materials has prompted extensive development of functional chitosan derivatives with enhanced physicochemical and biological properties. In this work, the conjugates of chitosan with 4-anisaldehyde (ChT-AA) were synthesised through Schiff base formation at various molar ratios and characterised using FT-IR, ¹H NMR, and thermal analysis techniques (TGA/DSC). The spectral data confirmed the successful formation of imine (C=N) linkages and the incorporation of aromatic anisaldehyde fragments into the chitosan structure. Thermal analysis demonstrated increased stability and a higher glass transition temperature for ChT-AA compared with native chitosan, indicating reduced polymer chain mobility and enhanced structural rigidity. Viscoelastic gels based on the synthesised ChT-AA (1:3) and methylcellulose were prepared and evaluated for their rheological properties and antimicrobial performance. Rheological studies revealed non-Newtonian shear-thinning behaviour of these gels with pronounced thixotropy, confirming reversible network recovery after shear deformation. Antimicrobial evaluation of chitosan, its 4-anisaldehyde conjugate (ChT–AA, 1:3), and free 4-anisaldehyde revealed distinct activity patterns. The gels showed no inhibition in the disk diffusion assay, likely due to limited diffusion of the active components. In liquid media, both ChT and ChT–AA exhibited identical minimum inhibitory concentrations (MICs) against E. coli (0.313 mg/mL) and C. albicans (1.250 mg/mL), whereas ChT–AA showed two-fold stronger activity against S. aureus (0.313 mg/mL vs. 0.625 mg/mL for ChT). Free 4-anisaldehyde was most active against S. aureus (MIC = 0.175 mg/mL) but less effective against the other strains, confirming its narrower spectrum. These results indicate moderate antimicrobial efficacy in solution but limited activity in gel form due to restricted diffusion. Full article

Surgical site infections in oral and maxillofacial interventions are often exacerbated by biofilm formation, and current antimicrobial treatments are hampered by issues such as resistance and adverse effects. This article aimed to develop, characterize, and evaluate the antimicrobial activity of Lippia sidoides Cham. essential oil (LSEO) gel composed of poloxamer (P) and chitosan (C). Gas chromatography–mass spectrometry (GC-MS) analysis identified thymol as the major component of LSEO (71.04%). In situ P-gels containing LSEO (0.25–1.0%) were produced with and without C. The addition of C resulted in gels with nanometric particle sizes (263.8 ± 231 nm; PDI 0.39 ± 0.17) and a positive zeta potential (+4.81 ± 1.97 a + 8.19 ± 0.51 mV), exhibiting pseudoplastic behavior in rheological analysis. The sol–gel transition temperature (Tsol–gel) was found to be between 20 and 28 °C, with a transition time at 37 °C ranging from 18.76 ± 1.24 s to 46.46 ± 8.89 s. LSEO showed MIC values of 256, 128, and 128 µg/mL against Staphylococcus aureus, Escherichia coli, and Candida albicans, respectively, while in situ LSEO gels presented MIC values above 5 µg/mL for all tested strains. Therefore, the developed gel containing LSEO showed promising application in dentistry, offering a potential new treatment perspective for surgical site infections in oral and maxillofacial surgery. Full article

This study applies circular and sustainable principles to the formulation of biopolymer-based materials using naturally occurring additives. To improve the affinity between the host matrix and additives such as metal oxides, the work involves adding stearic acid-modified zinc oxide (f-ZnO) and sonicated titanium dioxide (s-TiO₂) to a polylactic acid and bio-derived polyamide 11 (PLA/PA11 = 70/30 w/w biopolymer blend via melt mixing. To evaluate the impact of the functionalization and sonication on metal oxides (i.e., f-ZnO and s-TiO₂) introduced into the PLA/PA11 blend, composites containing unmodified ZnO and TiO₂ prepared under the same processing conditions were compared with the modified ones. All of the composites were characterised in terms of their solid-state properties, morphology, melt behaviour, and photo-oxidation resistance. The addition of both f-ZnO and s-TiO₂ appears to exert a plasticising effect on the rheological behaviour, in contrast to unmodified ZnO and TiO₂. The presence of stearic acid tails on ZnO has been estimated at approximately 4%, whereas sonication reduces the diameter of TiO₂ particles by half. In the solid state, both unmodified and modified particles can reinforce the biopolymer matrix, enhancing the Young′s (elastic) modulus. Calorimetry analysis suggests that unmodified and modified metal oxide particles do not influence the glass transition of the PLA phase but affect the melt temperatures of both biopolymeric phases by reducing macromolecular mobility. Morphology analysis shows that the presence of both f-ZnO and s-TiO₂ particles does not reduce the size of the PA11 droplets. The f-ZnO particles, which have long stearic tails and are more compatible with the less-polar phase (PLA), are probably located at the interface between the two biopolymeric phases or in the PLA phase. Furthermore, s-TiO₂ particles, like TiO₂, do not reduce the dimensions of PA11 droplets, suggesting that there is no preferential location of the particles. Due to the presence of both f-ZnO and s-TiO₂, an increase in the hydrophobicity of the PLA/PA11 blend has been detected, suggesting enhanced water resistance. The photo-oxidation resistance of the PLA/PA11 blend is significantly reduced by the presence of unmodified metal oxides and even more so by the presence of modified metal oxides. This suggests that metal oxides could be considered photo-sensitive degradant agents for biopolymer blends. Full article

This paper presents a study of the thermal and rheological properties of isosorbide, showing that its degradation temperature (around 100 °C) is much lower than values previously proposed in the literature. Furthermore, remarkable calorimetric and viscoelastic behaviors, with features usually observed in semi-crystalline systems are presented. The onset of the melting is measured at 45 °C, while a glass transition occurs at −45 °C, followed by cold crystallization. Wide-angle X-ray diffraction confirmed the coexistence of crystalline domains and an amorphous fraction, which behaves as a molecular glass, with an estimated crystallinity of approximately 70%. Thermogravimetric analyses conducted under both air and nitrogen and at multiple heating rates, in line with ICTAC recommendations, established the robustness of the 100 °C degradation onset. These findings provide new structure–property relationships for isosorbide and open up new avenues for further research and development in this area. Full article

The performance of dental composites is strongly dependent on the type and content of ceramic fillers incorporated into the resin matrix. In this study, the effect of nanosilica (NS) fillers on the curing kinetics, physicochemical, thermal, and mechanical properties of Bis-GMA/TEGDMA-based dental composites was systematically investigated. A series of nanocomposites containing various weight fractions of NS was prepared and evaluated. The photocuring behaviour was analysed using differential scanning calorimetry (DSC), enabling the determination of polymerisation rate coefficients (propagation k_p and bimolecular termination k_t^b) and double bond conversion. The presence of nanosilica was found to influence chain mobility, as evidenced by changes in glass transition temperature (T_g). Rheological measurements provided insight into viscosity changes induced by NS incorporation, while mechanical tests confirmed reinforcement effects. A moderate but statistically significant correlation was observed between the NS content and mechanical performance. The results obtained correlate the rheological, kinetic, thermal, and mechanical properties of multiple types of silica in a single resin system using a consistent methodology. In addition, the results highlight the role of nanosilica in the regulation of the curing dynamics and the increase in the mechanical integrity of methacrylate-based dental composites, representing a promising strategy for the development of next-generation restorative materials. Full article

Shape-memory polymers (SMPs) are a unique class of smart materials capable of recovering their original shape upon external stimuli, with thermoresponsive polyurethane (PU) being one of the most widely studied systems. However, the relatively low mechanical strength, thermal stability, and durability of PU limit its broader functional applications. PU/ND composites containing 0.1–0.5 wt.% ND were fabricated via melt blending and injection molding method. The objective was to evaluate the effect of ND reinforcement on the mechanical, scratch, thermal, rheological, and shape-memory properties. Results show that tensile strength increased up to 114% and Young’s modulus by 11% at 0.5 wt.% ND, while elongation at break decreased due to restricted chain mobility. Hardness improved by 21%, and scratch resistance was significantly enhanced, with the coefficient of friction reduced by 56% at low loads. Thermal stability was improved, with the maximum degradation temperature shifting from 350 °C (pure PU) to 362 °C (0.5 wt.% PU/ND) and char yield increasing by 34%. DSC revealed an increase in glass transition temperature from 65 °C to 68.6 °C. Rheological analysis showed an 89% reduction in damping factor (tan δ), indicating enhanced elasticity. Shape-memory tests confirmed notable improvements in both shape fixity and recovery ratios across successive cycles compared to neat PU, with the highest enhancements observed for the 0.5 wt.% PU/ND nanocomposite—showing up to 7.6% higher fixity and 32% higher recovery than pure PU. These results demonstrate that ND reinforcement effectively strengthens PU while preserving and improving its shape-memory behavior, making the composites promising candidates for high-performance smart materials in sensors, actuators, and aerospace applications. Full article

In this study, aiming to develop novel biocomposites that offer competitive properties while retaining their renewable and biodegradable characteristics, a biodegradable polymer matrix (Mater-Bi^® HF51L2) was reinforced with natural particles extracted from the culm and leaf of Cymbopogon flexuosus (lemongrass). Particles (<500 µm) were incorporated at 10 and 20 wt.% via twin-screw extrusion followed by compression moulding. Morphological analysis via SEM revealed distinct structural differences between culm- and leaf-derived particles, with the latter exhibiting smoother surfaces, higher density, and better dispersion in the matrix, resulting in lower void content. Quasi-static mechanical tests showed increased stiffness with filler content, particularly for leaf-based composites. This material, at 20 wt.% filler loadings, enhanced the tensile and flexural moduli of the neat Mater-Bi approximately three and two times, respectively, a result attributed to enhanced interfacial adhesion. Rheological measurements (rotational and capillary) indicated significant increases in complex viscosity, particularly for leaf-filled systems, confirming restricted polymer chain mobility and good matrix–filler interaction. Dynamic mechanical thermal tests (DMTA) results showed an increased storage modulus and a shift in glass transition temperature (T_g) for all biocomposites in comparison to Mater-Bi matrix. Specifically, the neat matrix had a T_g of −28 °C, which increased to −24 °C and −18 °C for the 20 wt.% culm-reinforced and leaf-reinforced biocomposites, respectively. Overall, the leaf-derived particles demonstrated superior reinforcing potential, effectively improving the mechanical, rheological, and thermal properties of Mater-Bi-based biocomposites. Full article