This in vitro study evaluated the effects of accelerated chemical aging on the flexural properties and surface wettability of additively manufactured denture base and teeth specimens reinforced with fumed silica. Denture base specimens were prepared as an unfilled control and with 20 wt.% fumed silica using two nominal particle sizes (110 and 500 nm), whereas denture teeth ones were prepared as an unfilled control and with 10 and 20 wt.% fumed silica (100 nm). Specimens for rectangular flexural (64.0 × 10.0 × 3.3 mm; n = 5 per group) and wettability (50.0 × 50.0 × 3.3 mm; n = 3 per group) tests were fabricated using a digital light processing (DLP) 3D printer, post-processed, and then immersed at 37 °C in artificial saliva (pH 6.2), sodium bicarbonate solution (pH 9.1), or acetic acid solution (pH 3.3) for 2, 4, and 6 weeks for accelerated chemical aging. Flexural strength and modulus were determined using three-point bending, while static contact angle, contact-angle hysteresis, and optical microscopy were used to evaluate aging-induced surface changes. Incorporation of 20 wt.% fumed silica increased the initial flexural modulus and flexural strength of the denture specimens by approximately 80% and 27%, respectively. All materials exhibited time-dependent degradation during aging, with acidic conditions mainly resulted in the greatest reductions in flexural properties. Silica reinforcement improved stiffness retention in denture base resins and reduced aging-induced deterioration, although its effects on denture teeth resins depended on filler loading and aging medium. Changes in contact angle and contact-angle hysteresis were associated with changes in flexural properties, indicating that surface wettability characterization may serve as a complementary nondestructive approach for assessing aging-induced degradation and predicting the service life of 3D-printed dental materials.
Plastic waste, along with ubiquitous microplastics, is one of the most pressing environmental challenges today. In light of these concerns, biodegradable plastics have been considered a promising alternative (to conventional plastics). This article aims to provide information to answer the question of whether biodegradable plastics have the potential to be used in sliding components such as sleeve bearings or dynamic seals. The study involved testing nine biodegradable plastics. Their friction and wear were assessed under various pressures and velocities using a pin-on-disc test rig. The following materials were identified as the most promising for use in sliding components, ranked from most to least promising: PBAT, PBS, PBSA, CA and allPHA. The materials tested exhibited differences in stiffness, ranging from flexible PBAT through the slightly stiffer PBS and PBSA till the more rigid CA and allPHA. A wide range of flexibility is highly desirable, as different types of sliding components (e. g. dynamic seals, sleeve bearings or slide guides) require varying flexibility. At higher contact pressure and sliding velocity, PVA and PCL exhibited such severe wear that reliable measurements could not be obtained, whereas PLA underwent thermal deformation due to the heat generated during friction. PPC wore extremely rapidly even under the lowest of the applied operating conditions. A comparison of the friction and wear properties of the investigated biodegradable polymers with those of non-biodegradable polymers widely used in sliding components showed that the biodegradable polymers do not differ significantly from the non-biodegradable ones. There is a potential for the use of the biodegradable polymers in sliding components. However, sliding components typically utilise polymer-based composites rather than the unmodified polymers. Therefore, future research should focus on developing composites based on biodegradable polymers with additives intended to reduce friction and wear, followed by further experimental investigations in order to provide a more comprehensive answer to the question of whether biodegradable plastics can be used in sliding components.
This study demonstrates the critical role of test frequency in assessing the deterioration of the upper service temperature rheological properties of reactive elastomeric terpolymer-modified asphalt cements (RT-ACs) during storage. RT-ACs were stored in sealed tubes at 120, 135, 150, and 165 °C for up to 7 days. Significant rheological deterioration was observed at 135 °C and became more pronounced as the storage temperature was increased. After 7 days at 150 °C, the non-recoverable creep compliance increased by a factor of 4.2, while the complex viscosity decreased by 50%. The deterioration was primarily associated with weakened interactions between the RT polymer and asphalt cement during storage. Across the investigated conditions of RT polymer type, asphalt cement grade, and test temperature, deterioration was more pronounced at lower test frequencies (ω < 1 rad/s). Owing to their high molecular weight, RT macromolecules exhibit slow molecular relaxation. The formation of a network between RT and asphalt cement further restricts molecular mobility, due to which the deterioration was primarily observed at lower test frequencies (ω < 1 rad/s). Importantly, storage-induced deterioration of RT-ACs adversely affected the performance of the corresponding asphalt mixtures. After one week of storage at 150 °C, Marshall stability and fatigue life decreased by 20%, indirect tensile strength decreased by 30%, moisture susceptibility increased by 10%, and rut depth increased by 60%. These findings highlight the importance of evaluating RT-ACs at low test frequencies (ω < 1 rad/s) to assess the impact of elevated storage temperatures, leading to reliable quality assessment, classification, and performance evaluation.
Cartilage defects severely compromise patients’ quality of life, as the unique structural characteristics of native cartilage endow it with extremely limited self-repair capacity. Mesenchymal stem cells (MSCs) possess tremendous therapeutic potential for cartilage tissue engineering due to their multilineage differentiation capability; however, technical bottlenecks associated with current cell delivery systems greatly restrict their clinical translation. Herein, we fabricated an injectable, multifunctional hydrogel microsphere system (PGCT-MS). Specifically, arginine-glycine-aspartate (RGD) sequences conjugated on gelatin molecules facilitate MSC adhesion, while chondroitin sulfate—an essential component of the chondrocyte extracellular matrix—constructs a favorable microenvironment for MSC spreading. Moreover, polydopamine modification on the microsphere surface enables efficient immobilization and sustained release of transforming growth factor-β3 (TGF-β3), which effectively induces the chondrogenic differentiation of bone marrow MSCs (BMSCs) at cartilage defect sites after in situ injection. In vitro experimental results demonstrated that PGCT-MS significantly enhances BMSC adhesion and chondrogenic differentiation, as verified by the upregulated expression of chondrogenic marker genes, and exhibits excellent adhesion affinity for native cartilage matrices. In vivo animal studies further validated that BMSC-loaded PGCT-MS markedly accelerates high-quality cartilage regeneration. Collectively, this multifunctional therapeutic delivery system provides a promising and feasible strategy for clinical cartilage defect repair.
1,8-Dihydroxynaphthalene-derived allomelanin nanoparticles (AMNPs) were incorporated into poly(vinyl alcohol) (PVA) films at low loadings of 0.1–0.7 wt.% to regulate their mechanical, optical, photothermal, and UV-aging properties. The 0.3 wt.% film exhibited the best measured strength–ductility balance, with a tensile strength of 103.8 MPa and an elongation at break of 102.1%, while retaining partial visible transparency. Increasing the AMNPs loading enhanced UV attenuation and photothermal heating but reduced visible-light transmittance. The 0.5 and 0.7 wt.% films reached steady-state temperatures of 60.7 and 62.4 °C, respectively. In the curcumin photodegradation test, the 0.3 wt.% film limited degradation to 6% after 50 min of UV exposure, whereas the 0.5 and 0.7 wt.% films nearly completely suppressed degradation. After 120 h of laboratory UV irradiation, the AMNP-containing film showed less surface roughening than neat PVA. These results reveal composition-dependent performance windows: 0.3 wt.% favors mechanically robust and partially transparent UV-protective films, whereas 0.5–0.7 wt.% favors stronger light shielding and photothermal conversion.
This study provides a description of the systematic investigation of the thermal response of collagen hydrogel phantoms, which serve as a model for venous wall tissue, to endovenous laser ablation (EVLA). We investigated two key wavelengths (980 nm and 1470 nm) and two optical fibre types (bare and radial). Applying a combination of numerical simulations and controlled experiments, we analysed the heat distribution, peak temperatures and spatial extent of the thermal damage. Furthermore, the structural alterations of the collagen across its hierarchical organisation were assessed applying complementary analytical techniques, including high-performance liquid chromatography (primary structure; amino acid composition), Fourier transform infrared spectroscopy (secondary structure), and scanning electron microscopy (fibrillar organisation and morphology). Only a small number of studies have systematically combined thermal modelling with the quantitative analysis of the collagen composition, secondary structure and fibrillar morphology within a single controlled experimental platform. The results indicated that 1470 nm radiation, particularly with respect to the radial fibres, provides for more localised heating and effective collagen modification than 980 nm radiation and results in the confinement of the thermal damage to, and the more pronounced structural disruption of, the collagen matrix. These findings established a consistent relationship between the laser parameters, thermal distribution and collagen structural response, thus providing the structural basis for the understanding of the differences observed between the clinical EVLA outcomes. This approach provides a more rational basis for the optimisation of the EVLA parameters and reduces the reliance on empirically-derived treatment protocols.
The development of advanced engineering applications requires materials with specific properties, yet epoxy-based composites' inherent brittleness is still a major limitation. Although graphene nanoplatelets (GNPs) can improve properties, their homogenous dispersion often results in restricted performance at high concentrations. This study fills a research gap in understanding functional gradation (FG) of nanoparticles in fiber-reinforced polymer (FRP) structures, focusing on localized damage resistance and fracture morphology correlations. To address these challenges, glass-fiber/epoxy laminates were fabricated with a controlled, layer-wise variation of GNP concentration through the laminate thickness, producing continuous (FG1), symmetric (FG2, FG3), and asymmetric (FG4) gradation profiles, which were evaluated against a neat laminate (N-G) and a laminate with uniform GNP dispersion (NFG) under quasi-static indentation (QSI) and flexural loading. Results revealed that the performance of composites was significantly influenced by the through-thickness distribution of GNPs. In terms of flexural energy and stiffness, the asymmetric FG4 was the most effective, with gains of 54.17% and 46.49%, respectively. QSI resistance was sensitive to both indenter geometry and gradation pattern, with FG structures showing improved penetration resistance and load-bearing capabilities. Morphological examination verified that these alterations arise from a combination of toughening mechanisms, such as matrix pinning and crack deflection. The outcomes reveal that spatial GNP dispersion exceeds uniform filling under specific loading conditions particularly hemispherical-indentation resistance, flexural stiffness, and damage tolerance while NFG remains preferable for flexural strength and flat-indentation load capacity, indicating that these strategies should be optimized based on specific loading conditions.
Poly(lactic acid) (PLA) is widely used in fused deposition modeling (FDM), but its recyclability is limited by cumulative thermomechanical degradation, and the combined effects of reprocessing, filler incorporation, and thermal aging on PLA/graphite composites remain poorly understood. This study addresses this gap by systematically investigating the effects of graphite content (0, 2.5, and 5.0 wt%), reprocessing cycles (1x, 5x, and 10x), and accelerated thermal aging at 105 °C on the structural, rheological, thermomechanical, and mechanical behavior of PLA-based composites for FDM. Reprocessing induced progressive matrix degradation, with melt flow rate increasing markedly and tensile strength decreasing by up to 35.6% for neat PLA after ten cycles. Graphite acted as a physical and microstructural modifier, improving stiffness and reducing moisture uptake under moderate reprocessing, but its reinforcing efficiency declined markedly under severe degradation. Accelerated thermal aging led to a rapid and substantial loss of tensile strength within the first days of exposure across all formulations, confirming the intrinsic thermal instability of the PLA ester backbone regardless of graphite content. These findings establish direct correlations between molecular-scale degradation and macroscopic performance, contributing to the rational design of recycled PLA/graphite filaments for circular economy-oriented FDM applications.
Flexible tactile sensors enable applications requiring intimate mechanical contact with soft tissues or conformable integration on deformable robotic surfaces. Despite extensive exploration of functional materials, performance remains frequently constrained by inefficient stress transfer and unstable interfacial contact within conventional planar architectures. The incorporation of biomimetic microstructures offers a versatile strategy to simultaneously modulate mechanical deformation and electrical signal evolution. Hierarchical geometries inspired by human skin, fibrous tissues, and natural surfaces reshape local strain distribution and interfacial contact dynamics, thereby governing the overall electromechanical transduction efficiency. Rather than relying exclusively on intrinsic material conductivity or dielectric permittivity, structural engineering emerges as a powerful parameter for signal amplification. In this review, we first outline the fundamental working principles and key characteristics of piezoresistive, capacitive, piezoelectric, and triboelectric tactile sensors. We then survey representative biomimetic geometric designs and elucidate how their mechanical behavior translates into enhanced electrical performance. Fabrication approaches are critically evaluated with respect to scalability, reproducibility, and compatibility with large-area processing. Finally, we discuss outstanding challenges concerning structural durability, system integration, and long-term environmental reliability.
Thermoresponsive chitosan-based hydrogels are promising injectable wound dressings; however, their clinical translation is often hindered by insufficient mechanical robustness and poor structural stability under exudate-rich conditions. In this study, we developed multifunctional octanoyl glycol chitosan/gallic acid (OGC/GA) thermogels through the integration of phenolic-mediated supramolecular and dynamic covalent interactions within a thermoresponsive glycol chitosan network. The resulting thermogels preserved rapid temperature-triggered sol-gel transition, enabling minimally invasive injection and in situ gelation at physiological temperature. Incorporation of GA significantly reinforced the hydrogel network, leading to enhanced compressive strength, physical stability, tissue adhesion, and self-healing capability, while maintaining favorable injectability. In particular, the optimized formulation exhibited approximately 20-fold higher mechanical strength than pristine OGC thermogels. Moreover, the OGC/GA thermogels demonstrated intrinsic antioxidant and broad-spectrum antibacterial activities, showing >99% antibacterial efficacy against both E. coli and S. aureus. Importantly, GA incorporation markedly improved hemostatic performance, reducing blood loss by approximately 88-95% in a mouse liver hemorrhage model. Collectively, these multifunctional OGC/GA thermogels represent a promising injectable platform with enhanced mechanical robustness and biological functionality for hemorrhage control and wound protection.
The effect of resin softening point (SP) and hydrogenation on the in-rubber properties of silica-filled SSBR/BR tire tread compounds was investigated using indene-coumarone hydrocarbon resins with SP values ranging from 10 to 160 °C. The resins were incorporated by partially replacing TDAE oil, while a hydrogenated version of the resin with an SP of 10 °C was included to evaluate the influence of residual unsaturation. Increasing resin SP led to higher Payne effect, crosslink density, hardness, and stiffness, indicating stronger filler networking and reduced polymer mobility. In contrast, low-SP resins behaved more similarly to plasticizers, promoting softer and more flexible compounds. Dynamic mechanical analysis showed increased hysteresis with increasing SP. Despite the differences in reinforcement and stiffness, abrasion resistance remained similar to the reference, suggesting a balance between reinforcement and elastic deformability. Hydrogenation reduced the interference of the resin with the vulcanization system, resulting in improved crosslink density and mechanical properties. Overall, resin softening point and hydrogenation were shown to be effective parameters for tailoring the performance of silica-filled tire tread compounds.
An experimental investigation was conducted to characterize the mechanical behavior of high-density polyethylene (HDPE, PE100-RC) for offshore pipe applications. Despite its industrial relevance, experimental data for extruded HDPE in bare and welded conditions remain limited. In this study, creep and fatigue tests were performed under uniaxial loading at room temperature (24 °C). Long-term creep tests were carried out on a custom-designed machine with durations ranging from 71 to 1464 h, revealing that primary and secondary creep account for 60% of the time to failure. The influence of specimen thickness (4, 8, and 12 mm) was investigated, showing no significant effect on creep life. S–N curves were obtained at load ratios of R=−1 and R=0.1 for both bare and welded specimens, with cycles to failure ranging from 5×103 to 4×105 at 0.5 Hz. Distinct failure modes were identified: fatigue crack initiation at R=−1 and excessive elongation at R=0.1. Additional tests at R=0.1 were performed at 0.1 and 0.05 Hz, suggesting that a frequency effect of a factor of 6 on cycles to failure may occur, depending on the applied stress range. The experimental results indicated that welding reduces fatigue life at R=−1, but does not significantly influence cyclic creep at R=0.1. This behavior was attributed to the bulk nature of cyclic creep deformation, which is less sensitive to local heterogeneities introduced by welding.
Supercritical carbon dioxide (S-CO2) is an emerging working fluid for high-efficiency energy systems, but its high diffusivity and solvent-like character can trigger swelling, plasticization, and property drift in polymer insulation and sealing components. Here, we use the ketone/ether ratio as a molecular-structure variable to clarify why different poly(aryl ether ketone)s (PAEKs) respond differently to high-temperature S-CO2 exposure. PEEK, PEK, and PEKK were aged at 10 MPa under two temperatures (150 °C and 200 °C) and two exposure durations (120 h and 480 h), followed by coupled swelling, spectroscopic, thermal, crystalline rearrangement, mechanical, and dielectric characterization. All three PAEKs retained strong dimensional stability, with mass changes below 1.7% and linear dimensional changes below 1.5%. FTIR and TGA/DTG revealed no detectable chemical degradation, indicating that the aging response was governed mainly by physical rearrangement. However, the mechanical outcomes diverged sharply with chain structure. PEEK and PEK showed hardness loss and increased elongation at break under severe exposure, consistent with S-CO2-assisted free-volume expansion and plasticization. In contrast, ketone-rich PEKK showed the lowest mass change (0.88%) and the highest first-heating crystallinity (39.34%) after 200 °C/480 h aging, while retaining hardness, tensile stability, and dielectric breakdown resistance. Overall, these results support a crystalline-domain-locking interpretation for ketone-rich PAEKs, in which chain rigidity and exposure-induced crystalline consolidation jointly help resist coupled swelling-plasticization damage in high-temperature S-CO2 systems.
Breaking the intrinsic trade-off between dielectric constant (Dk) and dielectric loss (Df) in polymer dielectrics remains a central challenge in high-frequency material design. In this study, a molecular design framework is established to decouple Dk and Df in poly(ester imide) (PEsI) systems by regulating torsional dynamics and dipole architecture simultaneously. Ortho-methyl substitution is introduced to impose torsional constraints along the imide backbone, while ester-isomer engineering enables precise modulation of dipole distribution and intermolecular packing through connectivity control. Combined experimental and computational analyses reveal that the dielectric response is governed not solely by fractional free volume but by the coupled interplay of packing efficiency, dipole orientation, and constrained chain dynamics. T–2MP exhibits a low Dk of 2.52 at 10 GHz, indicating an optimal balance between steric expansion and chain alignment. Further, copolymerization enables the independent tuning of dielectric parameters, yielding T–2MP/B (1:1) with an ultra-low Df of 0.0022 and a Dk of 2.84. This behavior originates from the favorable ester geometry of BPTP, which promotes dense packing, reduces the dipole moment, and suppresses electronic polarization. All PEsI copolymers maintain high thermal stability (Td5% > 474 °C) and low thermal expansion (CTE < 14.4 ppm K−1). This work provides a generalizable molecular design strategy for overcoming the Dk–Df trade-off in polymer dielectrics, offering a pathway toward high-performance materials for next-generation high-frequency electronics and advanced packaging.
Material extrusion (MEX) has attracted increasing attention for additive manufacturing in extreme environments. In this study, the thermal shock durability of MEX-fabricated (MEXed) oyster shell-filled PLA was evaluated after 100 thermal shock cycles between −30 °C and 85 °C. The dimensional changes remained below 4%, although anisotropic deformation dependent on the filament deposition direction was observed. Thermal shock caused only minor reductions in tensile strength (0.8% and 5.7% for the longitudinal and transverse specimens, respectively), whereas the elongation at break decreased by 19.0% and 16.5%, accompanied by the disappearance of the yielding behavior. SEM observations revealed a smoother fracture surface after thermal shock while maintaining nearly identical porosity (∼3.7%). In addition, the melting enthalpy approximately doubled after thermal shock, indicating increased crystallinity, which explains the reduced ductility and more brittle fracture behavior. These findings demonstrate that MEXed oyster shell-filled PLA maintains excellent dimensional stability and tensile strength under repeated thermal shock despite reduced ductility, providing useful insight into the development of sustainable MEX feedstocks for additive manufacturing in extreme thermal environments.
Conventional polysiloxane-based hybrid materials for LED encapsulation suffer from typically low refractive indices, limited optical transmittance, and extended cure times. Therefore, a systematic evaluation of curing behavior, mechanical hardness, refractive-index dispersion, optical transparency, thermal stability, and thermo-optical aging resistance is essential for assessing their applicability as optical encapsulants. To address these limitations, an omnidirectional polysiloxane hybrimer (OPH) was prepared by coupling phenyl-rich phenyl vinyl oligosiloxane (PVO) with omnidirectional cyclotetrasiloxane (OCS) through Pt-catalyzed hydrosilylation and was systematically tested as a high refractive-index optical encapsulant. Spectroscopic ellipsometry and thermogravimetric analysis confirmed that OPH exhibited high refractive indices of 1.64 at 450 nm, 1.61 at 520 nm, and 1.59 at 635 nm, together with a 5% weight-loss temperature (T5%) of 352 °C. A controlled Si-H/vinyl ratio enabled the formulation to achieve 96.5% optical transmittance at 450 nm for 2 mm thick films and rapid thermal curing to a Shore D hardness of 82.5 within 1.5 h at 180 °C. DMA further showed that OPH exhibited a higher Tg (54 °C) and rubbery-region storage modulus (356 MPa) than the PSH system (37 °C and 183 MPa), supporting the formation of a more highly cross-linked and mechanically robust network. After thermal aging at 200 °C for 720 h, the transmittance at 450 nm decreased only from 96.5% to 95.5%, and the yellowness-index change remained as low as ΔYI = 0.02, indicating strong thermo-optical and color stability under accelerated aging conditions. These results demonstrate that the OCS-based omnidirectional cross-linking strategy provides a favorable balance of refractive-index enhancement, optical transparency, curing efficiency, mechanical hardness, and thermo-optical durability, highlighting OPH as a promising material platform for optical encapsulation.
Induction welding of thermoplastic composites offers substantial application potential, yet uncertainty in the heat generation mechanisms at the welding interface severely hinders uniform temperature field control. This study presents a quantitative methodology to decouple the heat generation mechanisms in CF/PEEK laminates with varying ply angles. Four stacking configurations ([0/30]6, [0/45]6, [0/60]6, and [0/90]6) were characterized for their electrical and thermal properties. A microscale heat generation model was established to distinguish the contributions of fiber heating, contact resistance heating, and dielectric hysteresis. Results reveal that junction heating exceeds fiber heating by 106-107 times. The ratio of dielectric hysteresis to contact resistance heating increases monotonically from 2.0512 to 2.8241 as the layup angle increases from 30° to 90°, with dielectric hysteresis dominating (67.2%-73.9%). This trend is attributed to the significant reduction in interlaminar contact resistivity with increasing angle, which diminishes contact resistance heating efficiency and relatively enhances the dominant role of dielectric hysteresis. An angle-dependent compensation coefficient method is proposed to enable quantitative conversion of heat generation efficiency across different layups. Furthermore, a transient three-dimensional finite element model incorporating layup angle is developed and validated, overcoming the conventional limitation to orthogonal layups. This work provides a robust theoretical and simulation framework for process optimization and temperature homogenization in induction welding of thermoplastic composites.
Self-healing polyurethane elastomers with dynamic crosslinking structures possess great potential for functional development. However, most existing studies focus on the regulation of macroscale properties, lacking in-depth microscopic analysis of crosslinked networks, which makes it challenging to elucidate the synergistic mechanism between mechanical and self-healing properties. Herein, modified polyurethane was used as the matrix, and tannic acid (TA) was introduced to construct PU-HPBA/TA self-healing elastomers crosslinked by a synergistic network of boroxine rings and multiple hydrogen bonds. Systematic studies were conducted by combining macroscale structural and property characterization with molecular dynamics (MD) simulations. The results show that TA can effectively optimize the crosslinked network. The sample with a TA content of 4.4 wt% exhibits the optimal mechanical properties, with a tensile strength of 9.22 ± 0.32 MPa, an elongation at break of 882.4 ± 47.6%, and a self-healing efficiency of 79.3 ± 3.2%, achieving a balance between structural stability and self-healing ability. MD simulations reveal dynamic evolution behaviors of three distinct hydrogen bond species at the microscopic level, confirming that PU-TA hydrogen bonds dominate the system, which provide microscopic insights into polyphenol-modified boron-based self-healing elastomers. This study provides a new strategy for the design of self-healing polyurethanes, and molecular simulations offer microscopic support for the mechanism research of dynamic bond self-healing systems, while expanding the application prospects of bio-based polyphenol-modified elastomers.
Achieving a circular plastics economy depends strongly on effective plastic recycling. Mechanical recycling of post-consumer plastic waste plays a predominant role in this context. However, odors and volatile organic compounds (VOCs) present challenges for the recycling industry and threaten the quality and circularity of recycled plastics. One approach to tackle odor contamination is the use of adsorbents — porous materials that adsorb volatile substances. Various adsorbents, including zeolites and cyclodextrins, show promise for odor mitigation, but no universal solution exists across different recyclates. As a result, identifying a suitable adsorbent for a given recyclate remains a challenge. In this study, a rapid characterization method is presented to screen odor adsorbents directly on the additive, without any processing steps, for their effectiveness in removing VOCs from odor-contaminated plastics. The method was validated through internal laboratory repeatability and precision assessments, and proof of principle was demonstrated using a post-consumer polypropylene recyclate with four different adsorbents. Results reveal variations in VOC adsorption performance across adsorbents; notably, a synthetic zeolite achieved up to 80% VOC adsorption. The method enables rapid identification of promising adsorbents for VOC reduction and pre-evaluates candidates for further investigations.
In this study, novel polymer/graphene oxide (GO) composites were engineered for the adsorption and recovery of phenolic compounds from olive mill wastewater. A pentafluoropyridine-derived monomer was synthesized and subsequently polymerized via polycondensation to yield pyridine-containing polymers. Composites incorporating 5, 10, and 15 wt% GO were then prepared and evaluated for the adsorption of major phenolic constituents commonly detected in olive mill wastewater, namely hydroxytyrosol (HT), tyrosol (TR), caffeic acid (CA), and ferulic acid (FA). These compounds are recognized for their remarkable antioxidant activity and their broad potential applications in the cosmetic, pharmaceutical, nutraceutical, and food sectors. The materials also demonstrated the capability for the simultaneous co-adsorption of multiple phenolic compounds. Adsorption kinetics and equilibrium studies indicated that the process was best described by the pseudo-first-order kinetic model and the Langmuir isotherm model, respectively, suggesting predominantly monolayer adsorption behavior. Among the synthesized materials, the P-GO10 composite exhibited superior adsorption performance, achieving maximum adsorption capacities of 95.5 mg g−1 for hydroxytyrosol and 81.3 mg g−1 for tyrosol, with adsorption equilibrium attained within approximately 24 h. Desorption was effectively achieved through methanol washing, and the regenerated adsorbent retained approximately 73% of its initial adsorption efficiency after five consecutive adsorption–desorption cycles, demonstrating satisfactory stability and reusability. Collectively, these findings underscore the significant potential of P–GO composites as efficient, robust, and reusable adsorbent materials for the recovery and valorization of high-value phenolic compounds from agro-industrial wastewater streams.
