Search Results (591)

The rapid development of additive manufacturing has enabled the production of personalized biomedical devices, including custom orthoses that must retain their structural integrity under demanding physiological conditions. This study evaluates the performance of 3D-printed polymers—blue and white polylactic acid (PLA), Standard Blue Resin, and an ecological soy-based resin—after exposure to simplified, controlled saline environments related to sweat contact and hygiene-associated conditions. Moisture absorption and Shore A hardness were analyzed as response variables to assess material stability under different experimental conditions. A surface methodology based on a Box–Behnken design was used to quantify the effects of specimen thickness (x₁), NaCl concentration (x₂), and immersion time (x₃) on the selected dependent variables. The results indicate that Standard Blue Resin showed the greatest surface hardness stability, whereas the bio-based materials (PLA and ecological resin) were more susceptible to moisture absorption, particularly in thinner polymeric sheets. The fitted quadratic models provide a predictive framework for optimizing material selection and geometric design in biomimetic wearable devices, supporting the development of orthoses with improved durability, hygiene, and long-term functional performance. Full article

Background: The influence of surface sealants on the color stability of composite resin restorations remains controversial. This in vitro study evaluated the effect of two surface sealants on the color stability of a nanohybrid composite resin exposed to staining beverages. Methods: Ninety specimens of Enamel Plus HRi Bio Function (BF2) composite resin were divided into three groups: without sealant, with Embrace™ WetBond™ Seal-n-Shine™, and with Ena Bond Seal. Specimens were immersed in black tea, Coca-Cola^®, red wine, orange juice, coffee, or distilled water for 40 h. Color measurements were obtained before and after immersion using the OptiShade colorimeter in accordance with the CIELAB color system. Results: Significant differences were observed according to both the staining solution and the surface sealant applied (p < 0.001). Red wine produced the highest color changes in all groups, while coffee and black tea also caused clinically perceptible discoloration. The Seal-n-Shine™ group exhibited the highest ΔE values and greater color variation compared with the control group. In contrast, the Ena Bond Seal group exhibited chromatic behavior closer to that of the unsealed composite resin. Conclusions: Color stability was significantly influenced by both the staining solution and the applied surface sealant. Full article

This study reports the physicochemical characterization and structure–property relationships of rigid sheep wool/phenolic novolac panels developed as bio-based thermal insulation for building envelopes. Mixed Polish sheep wool was washed, mechanically opened, and formed into nonwoven mats, then impregnated with either neat or flame-retardant novolac resin to obtain lightweight boards with a fiber content of about 50 wt%. Elemental analysis, ICP-OES, FTIR spectroscopy, and laser and electron microscopy were used to evaluate the fiber composition, keratin structure, morphology, and fiber–matrix interfaces. Mechanical performance under three-point bending and shear, differential scanning calorimetry, thermogravimetric analysis, and transient hot-probe thermal-conductivity measurements were applied to link microstructure with functional behavior. Novolac impregnation transformed the compliant wool mat into self-supporting panels, increasing the flexural modulus to the 0.8–1.4 GPa range and flexural strength to approximately 48–52 MPa, while the shear modulus and work to failure rose by more than an order of magnitude relative to the loose wool reference. Thermal conductivity remained in a typical range for natural-fiber insulations (λ = 0.061 W·m⁻¹·K⁻¹ for the wool mat and 0.071–0.074 W·m⁻¹·K⁻¹ for the composites), although higher than that of expanded polystyrene. DSC and TGA confirmed that wool fibers remain thermally stable up to about 200–220 °C, that the novolac resin cures around 140 °C, with typical phenolic reaction enthalpies, and that both formulations generate high char residues of roughly 60–80 wt% at 600 °C under nitrogen, evidencing a strong charring propensity rather than directly quantifying fire resistance. Overall, the results position sheep wool/novolac panels between conventional bio-based insulation and structural composites and highlight their potential as sustainable, circular insulation materials for energy-efficient building envelopes. Full article

The adoption of sustainable construction materials in the building sector is increasing, driven by global net-zero targets, regulatory pressures, and growing demand for low-carbon and resource-efficient construction. In this context, this research investigates the feasibility of using bio-based fibre-reinforced epoxy resin composite laminates with recycled polyethylene terephthalate cores in structural insulated panels (SIPs) as an alternative to conventional SIP systems. Laminates were fabricated via a wet layup method using two epoxy resins and five fabric types, including flax, hemp, and recycled PET fabrics. Tensile and flexural testing revealed that hemp fabric paired with a fully bio-based epoxy provided the optimum combination of strength and elastic modulus. Small-scale SIP prototypes utilizing optimum laminate and rPET cores were tested for edgewise compression and flexure against expanded polystyrene (EPS) equivalents. The rPET SIPs demonstrated compressive and flexural capacities two to three times greater than the EPS panels. These findings demonstrate the potential of sustainable fabric-reinforced epoxy resin composite SIPs for specialized high-performance construction applications where enhanced structural capacity and sustainability are required. Although further work is needed to address cost, fire performance, and scalable manufacturing, the proposed system presents a promising alternative for next-generation sustainable building systems. Full article

In this study, salmon fish bone waste from the fish processing industry was converted into an inorganic ash filler by calcination and incorporated into an SLA-compatible photopolymer resin at 4, 8, and 12 wt.%. To compensate for filler-induced optical scattering and rheological changes, the printing parameters were systematically optimized, and the optimum conditions were identified as a layer thickness of 30 µm and an exposure time of 12 s. Tensile tests performed in accordance with ASTM D638 Type IV showed that fish bone ash significantly enhanced the tensile strength of the photopolymer matrix, increasing it from 24.8 MPa for the neat resin to 37.95 MPa at 12 wt.% filler loading. In contrast, increasing filler content reduced elongation at break and promoted a more brittle fracture response. Statistical evaluation using Welch ANOVA and Games–Howell post hoc analysis confirmed that filler loading had a statistically significant effect on tensile strength (p < 0.05). FTIR analysis revealed that the filler remained chemically stable within the matrix and that the interfacial interactions were predominantly physical rather than covalent. SEM observations indicated that low and medium filler loadings improved crack deflection and energy dissipation, whereas particle agglomeration at higher loading increased the tendency for brittle fracture. These findings demonstrate that fish bone ash can be used as a sustainable bio-waste-derived reinforcement to improve the mechanical performance of SLA photopolymer composites. Full article

The degradation of styrene-butadiene-styrene (SBS) modified asphalt under thermal-oxidative aging can reduce pavement service life. Lignin is a renewable material with active phenolic hydroxyl groups. Incorporating lignin into SBS modified asphalt may provide a potential bio-based auxiliary modification route. To investigate the antioxidative effect and rheological properties of SBS modified asphalt after adding lignin, a molecular dynamics test and experimental tests were employed. The molecular simulation results suggested that lignin preferentially associated with asphaltene and resin molecules and changed the molecular mobility of asphalt components in a component-dependent manner. The SBS/lignin composite modified asphalt was evaluated by temperature sweep (TS), Multiple Stress Creep and Recovery (MSCR), Linear Amplitude Sweep (LAS) and Fourier transform infrared spectroscopy (FTIR). Rheological tests showed that lignin increased the complex shear modulus and rutting factor. LAS results showed that lignin reduced the fatigue life of SBS-modified asphalt in the unaged state due to increased stiffness and embrittlement. However, after long-term aging, the lignin-containing binders retained higher fatigue resistance than the SBS-only control, which may be related to the slower evolution of oxidation-related functional groups and SBS-related spectral indices. FTIR analysis provided semi-quantitative evidence that lignin addition reduced the growth of sulfoxide-related bands and helped maintain the polybutadiene-related index during aging. Overall, lignin may serve as a potential auxiliary antioxidant modifier for SBS modified asphalt, while its exact source-specific molecular mechanism requires further verification. Full article

Heavy metal contamination of water by cadmium (Cd²⁺) and silver (Ag⁺) represents a significant environmental concern due to their toxicity and persistence. In this study, peptide-functionalized resins were evaluated as bio-inspired adsorbent materials for metal removal from aqueous solutions. Glycine-based and histidine-containing peptide sequences were synthesized via solid-phase peptide synthesis and immobilized onto Wang and Rink amide resins, with and without N-terminal acetylation. Adsorption capacity (Q, mg g⁻¹) was determined for each material. The results showed that adsorption performance strongly depends on both peptide structure and metal type. Higher adsorption capacities were consistently observed for Cd²⁺ (up to 7.9 mg g⁻¹) compared to Ag⁺ (up to 2.4 mg g⁻¹). Interestingly, histidine-containing resins exhibited superior performance, likely due to the presence of imidazole groups that enhance metal coordination. In contrast, the influence of resin type and N-terminal acetylation was less consistent, suggesting a secondary role of these factors. Overall, the findings provide an initial screening or proof-of-concept for peptide-functionalized resins and highlight the potential of these peptidyl resins as effective adsorbent materials for the removal of heavy metals from aqueous environments. Full article

Achieving a circular and climate-neutral bioeconomy by 2050 requires not only high-quality recycling but also the large-scale integration of renewable carbon from biomass and atmospheric CO₂ into material systems. Plastics represent the world’s largest and most rapidly growing carbon sink, positioning them as a critical intervention point for replacing fossil-based feedstocks with renewable alternatives. Because plastic packaging is one of the most visible material streams encountered by consumers in daily life, a transition toward sustainable, recyclable bioplastics has the potential to deliver both meaningful environmental benefits and strong societal impact, accelerating public awareness and acceptance of renewable carbon solutions. Poly(ethylene furanoate) (PEF)—a fully bio-based polyester synthesized from plant-derived 2,5-furandicarboxylic acid (FDCA) and monoethylene glycol (MEG)—offers a promising pathway toward more sustainable packaging due to its superior mechanical strength and gas-barrier performance relative to polyethylene terephthalate (PET). This study presents a cradle to grave life cycle assessment (LCA) of PEF resin production and PEF bottle applications, using industrially relevant, at-scale process data covering biomass feedstock conversion, polymer synthesis, packaging manufacture, use phase, and end of life. Bottle applications were selected as a focal point due to their technical maturity, commercial relevance, and suitability for direct comparison with incumbent PET systems. The results indicate that PEF can reduce greenhouse gas emissions by up to 71% and fossil resource depletion by 26% compared to PET at the resin level when biogenic carbon uptake is included. Moreover, the material’s enhanced functional properties enable lightweight, recyclable bottle designs with carbon footprint reductions of up to 88% for 500 mL formats under a baseline recycling rate scenario of 72%, with the remaining share directed to municipal solid-waste incineration with energy recovery. Sensitivity analyses reveal that virgin PEF maintains environmental advantages over PET even when PET incorporates high levels of recycled content, highlighting the complementary roles of renewable carbon and circular material strategies. Prospective scenario modeling underscores the importance of sustainable feedstock selection and process electrification, with sucrose-based routes offering the largest potential for further decarbonization. Overall, the findings demonstrate that PEF is a scalable biopolymer capable of delivering substantial climate benefits while supporting circularity objectives. By targeting a highly visible consumer application—plastic packaging—this transition amplifies the societal impact of adopting renewable carbon materials. The study provides actionable insights for policymakers, industry stakeholders, and sustainability practitioners working to advance a more resilient, renewable, and consumer-recognizable plastics economy. Full article

Acrylated epoxidized soybean oil (AESO) is a bio-based, biocompatible, and biodegradable photopolymerizable resin that exhibits shape-memory behavior, making it attractive for a wide range of biomaterial applications. Despite various strategies to fabricate porous AESO scaffolds for tissue regeneration, achieving high pore interconnectivity remains challenging. Herein, we demonstrate the utility and versatility of thermoreversible terpenes as porogens in AESO to enable the formation of highly aligned and interconnected pore architectures. More specifically, a blend of 90 wt% camphene and 10 wt% camphor was employed as the terpene system, since it could be completely melted at 70 °C, uniformly mixed with liquid AESO, and subsequently crystallized at −20 °C. This process generated a bicontinuous network comprising terpene crystals and liquid AESO, thereby enabling efficient UV photopolymerization of AESO. Following terpene removal via freeze-drying, highly aligned pore networks with excellent pore interconnectivity were obtained, which are hardly achievable using conventional liquid or solid porogens. The porosity and mechanical properties of the AESO scaffolds were tuned by adjusting terpene content. Porosity increased from 61.5 to 81.5% as terpene content rose from 60 to 80 vol%. As a result, tensile strength decreased from 0.29 ± 0.045 to 0.17 ± 0.017 MPa, while elongation at break increased from 20.2 ± 4.9 to 35.5 ± 1.34%. Furthermore, this approach is compatible with vat photopolymerization (VP), a 3D printing technique. As a proof of concept, dual-scale porous AESO scaffolds, composed of unidirectional channels surrounded by highly aligned porous frameworks, were successfully fabricated. These results indicate that a variety of dual-scale porous AESO scaffolds, with greatly enhanced mechanical properties at given porosities coupled with outstanding tissue regeneration, can be produced through VP using terpene porogens, in contrast to conventional porous scaffolds comprising uniform porous frameworks. Full article

Conventional epoxy polymers and their composites are increasingly challenged by environmental concerns, high manufacturing costs, and limited recyclability, necessitating the exploration of sustainable alternatives. Many research groups have sought to develop alternate polymers from various renewable resources, such as lignin, polyphenols, natural resins, saccharides, and plant oils. This new type of polymer has led to the emergence of bio-based polymers, which are often used with different reinforcements as bio-based composites. In this review, the synthesis of different bio-epoxy resins is discussed in detail along with their chemical structures. Subsequently, the enhancements in the properties of these bio-composites with the addition of different nanomaterials such as carbonaceous nanofillers (carbon nanotubes, graphene nanoplatelets, graphene oxide, etc.), cellulose-based nanomaterials, inorganic nano-silica (spherical and mesoporous), and nano-clay is explained. Lastly, the properties of these bio-composites and their applications in civil engineering are highlighted. This review has provided a detailed overview of the developments in bio-composites that can be used as a guide for the development of a new class of bio-composites using other alternate resources. Full article

Synthetic polymers are widely used in stone conservation, yet their long-term biological stability remains insufficiently evaluated. This study investigates the microbial susceptibility of three commonly used acrylic consolidants, Paraloid B-72, B-66, and B-44, applied to deteriorated limestone. Bacteria, fungi, and actinomycetes were isolated from a deteriorated limestone false door and screened for acid production. From each microbial group, only the strong acid-producing isolates were selected for further investigation, including evaluation of their ability to utilize the three Paraloid resins as sole carbon sources and their deterioration potential on limestone cubes before and after consolidation. Deterioration was assessed by weight loss, compressive strength testing, stereomicroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). All selected strong acid-producing isolates demonstrated the ability to grow on the tested polymers, confirming their biodegradation potential. Mixed microbial cultures caused greater weight loss and compressive strength reduction than single isolates, attributed to synergistic metabolic interactions. Among the consolidants, Paraloid B-72 showed the highest susceptibility to microbial attack, while Paraloid B-66 exhibited comparatively greater resistance, attributed to the steric hindrance of its isobutyl side groups and higher surface hydrophobicity. FTIR and XRD analyses confirmed ester bond hydrolysis, progressive gypsum formation, and structural alteration of the limestone substrate. These findings demonstrate that acrylic consolidants commonly used in stone conservation are not biologically inert and may actively contribute to biodeterioration under microbial colonization, highlighting the need for developing bio-resistant conservation materials. Full article

This study investigates the mechanical, structural, and thermal performance of bio-based composite laminates reinforced with nonwoven fibrous materials derived from polylactic acid (PLA), poly(butylene succinate) (PBS), and polyamide 1010 (PA1010). The fibrous reinforcements, produced using melt-blown and electrospinning techniques, were characterized in terms of morphology, fibre diameter distribution, and wettability, and subsequently incorporated into bio-resin laminates to strengthen them. The curing behaviour of the composites was evaluated using differential scanning calorimetry (DSC). The results demonstrate that fibre structure and morphology strongly influence resin impregnation and interfacial interactions. Mechanical properties varied significantly depending on the reinforcement type. PA1010-based laminates exhibited the highest strength and stiffness due to their compact and uniform fibrous structure. PBS-based systems showed intermediate behaviour, while PLA-based composites displayed lower strength but higher deformability. DSC results indicated that fibre type affected crosslinking efficiency. Thermogravimetric analysis (TGA) revealed similar initial thermal stability of laminates (T₅% ≈ 299–313 °C), governed by the resin matrix, while differences at higher temperatures reflected the type of reinforcement used. These findings highlight the importance of fibre morphology and interfacial compatibility in designing sustainable composite laminates reinforced with recycled fibrous materials. Full article

Purpose: This study provides a comparative evaluation of surface changes in BioHPP materials under routine professional hygiene procedures, which is recommended by dentists, twice a year. BioHPP is a polyetheretherketone polymer used in prosthetic dentistry as a frame material. The aim was to investigate whether routine dental cleaning procedures such as ultrasonic scaling and brushing affect the surface proprieties of prosthetic BioHPP restorations. This study was conducted to evaluate the surface properties of different restorations based on BioHPP (veneered with composite resin and polished) after brushing and ultrasonic scaling exposure. Materials and Methods: The BioHPP specimens were divided into three groups. The first group (marked BioHPP) served as a baseline reference for assessing the effect of different surface processing approaches, and no further treatment was applied. The specimens in the second group (BioHPP-P) were polished, while the specimens in the third group (BioHPP-C) were veneered with composite resin. Group BioHPP-P and BioHPP-C of samples was divided into three subgroups: 0—no treatment, 1—exposed to tooth brushing, 2—exposed to ultrasonic scaling. Untreated samples (subgroup 0) served as controls for evaluating treatment-related changes within groups 2 and 3. The surface morphology was investigated by atomic force microscopy (AFM). The structure of samples was analyzed using the XRD technique, and the surface wettability was evaluated. Results: The surface roughness of the samples was evaluated via root mean square (RMS) parameter. Baseline BioHPP specimens exhibited higher roughness values compared to the other analyzed groups. The roughness of the non-treated specimens (0) decreased in the line 59.18→28.84→14.51 nm. Treatment of the samples by brushing and ultrasonic scaling was associated with an increase in surface roughness. Variations in water contact angle values were observed. However, no consistent treatment-related trend could be established. Conclusions: Composite veneered BioHPP showed a tendency toward higher surface resistance to brushing and ultrasonic scaling. These findings should be interpreted within the limitations of an in vitro descriptive study. Full article

This research utilizes stereolithography (SLA) technology to analyze the mechanical properties of the fabricated parts. SLA operates by precisely hardening liquid resin layer by layer with a focused ultraviolet (UV) light, enabling the creation of precise shapes and intricate details. Plant-based resins are becoming increasingly popular as alternatives to conventional polymer resins. However, the mechanical performance of SLA-printed parts made from bio-based materials can vary significantly depending on the printing parameters. To achieve acceptable performance, the optimization of the printing parameters is crucial. This study investigates the impact of print parameters on the mechanical and morphological characteristics through the use of L27 Taguchi’s orthogonal array. For this purpose, a combination of the most influential controlled parameters, including layer thickness, exposure time, bottom layer count, bottom exposure time, lifting distance, lifting speed, and print orientation, was assessed. The mechanical properties of the samples were evaluated after washing and UV curing. The optimal parameter combination was identified using the signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) identified the significant parameters affecting the mechanical properties. The findings confirmed by the morphology analysis revealed that layer thickness, followed by bottom exposure time and exposure time, strongly influenced interlayer bonding and mechanical performance. Full article

Epoxy resins are widely used thermosetting polymers, but their limited toughness and flexural resilience restrict broader applications. In this study, diglycidyl ether of bisphenol A (DGEBA) epoxy was reinforced with 5 wt.% ceramic fillers of different origins: sol–gel alumina calcined at 550 °C (γ-Al₂O₃) and 1000 °C (α-Al₂O₃), silica derived from rice husk, silica from diatomaceous earth, and a hybrid alumina–silica mixture prepared by sol–gel and calcined at 1000 °C. Fillers were structurally characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field-emission scanning electron microscopy (FESEM). Mechanical properties were evaluated through tensile (ASTM D638) and flexural (ASTM D790) testing. All reinforcements enhanced the performance of neat epoxy. γ-Al₂O₃ provided superior tensile reinforcement compared to α-Al₂O₃, underscoring the importance of particle morphology and surface reactivity. The hybrid alumina–silica filler achieved the highest flexural strength of 50.6 MPa, compared to 9.91 MPa for the neat epoxy. Bio-derived silica showed improved flexural properties, although its tensile reinforcement was less pronounced compared to the sol–gel derived fillers. These results establish clear structure–property relationships and confirm that filler phase, morphology, and calcination temperature critically govern the mechanical performance of epoxy composites. Full article