Search Results (66)

Collagen-based biomaterials are widely used, but their relatively rapid biodegradation can limit functional duration. Such collagen constructs are widely used as barrier membranes in guided tissue and bone regeneration, where controlled degradation is essential for maintaining function. Although conventional crosslinking methods extend stability, they may introduce cytotoxicity, alter mechanical behavior, or hinder tissue integration. This study evaluated whether incorporating L-serine, a polar amino acid capable of hydrogen bonding, could modulate collagen structure and slow degradation without chemical crosslinking. L-Serine was selected because its hydroxyl-containing side chain can engage in biocompatible, hydrogen-bond–mediated interactions that offer a mild, non-crosslinking means of stabilizing collagen. Collagen scaffolds, prepared by incorporating L-serine into a collagen hydrogel followed by drying, were produced with 0–40 wt% L-serine and characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, circular dichroism, and scanning electron microscopy. In vivo degradation was assessed in a subcutaneous mouse model comparing unmodified collagen, collagen containing 40 wt% L-serine, and a commercially available bilayer porcine collagen membrane (Bio-Gide^®, composed of type I and III collagen), with residual area quantified by serial sonography and histological evaluation. Low-to-moderate L-serine incorporation preserved triple-helical features, while 40 wt% led to crystalline domain formation and β-sheet enrichment. L-serine–treated collagen exhibited significantly greater residual area (2.70 ± 1.45 mm²) than unmodified collagen (0.37 ± 0.22 mm², p < 0.05), although Bio-Gide^® remained the most persistent (5.64 ± 2.76 mm²). These findings demonstrate that L-serine incorporation can modulate collagen structure and degradation kinetics through a simple, aqueous, and non-crosslinking approach. The results provide preliminary feasibility data supporting amino acid–assisted tuning of collagen resorption properties and justify further evaluation using membrane-specific fabrication and application-relevant testing. Full article

Polyetheretherketone (PEEK) is a high-performance engineering plastic widely used in aerospace, automotive, and other industries due to its heat resistance and mechanical strength. However, its high friction coefficient and low thermal conductivity limit its use in heavy-load environments. Existing studies have extensively explored the individual effects of thermal processing or irradiation on PEEK. However, the synergistic mechanism between the initial microstructure formed by mold temperature and subsequent irradiation modification remains unclear. This paper investigates the coupled effects of injection molding temperature and electron beam irradiation on the tribology of carbon fiber-reinforced PEEK composites, with the aim of identifying process conditions that improve friction and wear performance under high load by controlling the crystal morphology and cross-linking network. Carbon fiber (CF) particles were mixed with PEEK particles at a 1:2 mass ratio, and specimens were prepared at injection molding temperatures of 150 °C, 175 °C, and 200 °C. Some specimens were irradiated with an electron beam dose of 200 kGy. The friction coefficient, wear rate, surface shape, and crystallinity of the material were obtained using friction and wear tests, white-light topography, SEM, and XRD. The results show that the injection molding temperature of the material influences the friction performance. Optimal performance is obtained at 175 °C with a friction coefficient of 0.12 and wear rate of 9.722 × 10⁻⁶ mm³/(N·m). After irradiation modification, the friction coefficient decreases to 0.10. This improvement is due to the moderate melt fluidity, adequate fiber infiltration, and dense crystallization at this temperature. In addition, cross-linking of chains occurs, and surface transfer films are created at this temperature. However, irradiation leads to a slight increase in wear rate to 1.013 × 10⁻⁵ mm³/(N·m), suggesting that chain segment fracture and embrittlement effects are enhanced at this dose. At 150 °C, there is weak interfacial bonding and microcrack development. At 200 °C, excessive thermal motion reduces crystallinity and adds residual stress, increasing wear sensitivity. Overall, while irradiation reduces the friction coefficient, the wear rate is affected by the initial microstructure at molding. At non-optimal temperatures, embrittlement tends to dominate the wear mode. This study uncovers the synergistic and competitive dynamics between the injection molding process and irradiation modification, offering an operational framework and a mechanistic foundation for applying CF/PEEK under heavy-load conditions. The present approach can be extended in future work to other reinforcement systems or variable-dose irradiation schemes to further optimize overall tribological performance. Full article

In this study, we present a novel high-thermal-conductivity-organosilicon potting adhesive developed for use in power modules. The adhesive is designed to enhance power modules’ thermal properties and mechanical strength, addressing the need for more efficient and reliable encapsulation materials in electronic applications. By optimizing the resin formulation, the adhesive exhibits improved tensile strength and elongation at break properties, making it particularly suitable for applications requiring high durability and resilience under thermal and mechanical stress. Herein, we propose a high-thermal-conductivity organosilicon electronic potting adhesive designed for power modules. The adhesive consists of two components: Component A and Component B. Component A is composed of a base polymer (0.5–10 parts), silicone resin (0.15–10 parts), plasticizer (0.5–5 parts), color paste (0.01–0.2 parts), thermally conductive filler (70–120 parts), filler treatment agent (2–8 parts), and a catalyst (0.1–2 parts). Component B includes a base polymer (0.5–10 parts), silicone resin (0.15–10 parts), plasticizer (0.5–5 parts), thermally conductive filler (70–120 parts), crosslinking agent (0.1–10 parts), chain extender (0.1–10 parts), and crosslinking inhibitor (0.01–1 part). The adhesive is designed to improve the tensile strength and elongation at break. These materials were engineered to facilitate easy repair and disassembly, ensuring cost-effective maintenance and reuse in power module systems. This work demonstrates the potential of the adhesive in advancing the performance and longevity of power electronics, providing valuable insights into its practical application for high-performance electronic devices. Full article

Compatibilizers that enhance sustainability and improve the miscibility of polymer blend components have garnered significant attention. This study investigates the difference between the synthetic chain extender Joncryl^® ADR 4468 and the natural epoxidized linseed oil (ELO) Merginat 8510100 as compatibilizers for thermoplastic starch/poly (butylene succinate) (TPS/PBS) blends. Blends containing 40% TPS and 60% PBS were prepared with 1, 3, and 5 phr of each compatibilizer, along with a reference with no additives. The properties of these blends were evaluated using tensile testing, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), rheology, and scanning electron microscopy (SEM). The findings indicate that while Joncryl^® ADR 4468 significantly improved tensile strength, it also resulted in a brittle fracture. In contrast, ELO batches exhibited greater ductility, albeit with lower tensile strength. These differences are attributed to the chain extension and minor cross-linking effects of Joncryl^® ADR 4468, compared to the increased chain mobility arising from ELO’s plasticizing and compatibilizing actions. Supporting evidence for these observations includes increased cold crystallization temperature (T_cc) and melting temperature (T_m), greater storage modulus along with higher complex viscosity, strengthened interfacial adhesion, and fewer morphological defects in Joncryl^® ADR 4468 blends. These results highlight the importance of selecting an appropriate compatibilizer based on specific application requirements. Overall, this study addresses the knowledge gap regarding the loadings of Joncryl^® ADR 4468 and ELO in TPS/PBS blends and provides a basis for further optimization strategies, such as the incorporation of binary compatibilizers, alternative grafting-based compatibilizers, and twin-screw blending modifications. Full article

The lower melt strength of biodegradable materials in comparison to low density polyethylenes raises serious issues regarding their processability via blown film molding. Thus, reliable rheological characterization is a viable option for assessing their efficient flow performance. The blends of poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT) modified with four chain-extending cross-linkers (CECLs) undergo shearing during extrusion and are subjected to extensional deformation during the subsequent film blowing. The shear viscosity data obtained with a capillary rheometer corresponded well to the molecular weights obtained by gel permeation chromatography, while an evaluation of elongational viscosity using a Sentmanat Extensional Rheometer failed due to sample sagging during the process of temperature setting and an unacceptable deviation from the theoretically supposed exponential decrease of sample cross-sections. Therefore, the response of the PBAT/PLA blends to elongation was determined via changes in the duration of time intervals corresponding to the rupture of elongated samples. An increased consistency of the PBAT/PLA blends with CECL, as previously indicated by dynamic mechanical analysis, differential scanning calorimetry, and scanning electron microscopy, was evaluated in this way. Full article

Identifying homologous vulnerabilities across diverse IoT firmware images is critical for large-scale vulnerability auditing and risk assessment. However, existing approaches often rely on coarse-grained components or single-dimensional metrics, lacking the semantic granularity needed to capture cross-firmware vulnerability relationships. To address this gap, we propose FirmVulLinker, a semantic profiling framework that holistically models firmware images across five dimensions: unpacking signature sequences, filesystem semantics, interface exposure, boundary binary symbols, and sensitive parameter call chains. These multi-dimensional profiles enable interpretable similarity analysis without requiring prior vulnerability labels. We construct an evaluation dataset comprising 54 Known Defective Firmware (KDF) images with 74 verified vulnerabilities and assess FirmVulLinker across multiple correlation tasks. Compared to state-of-the-art techniques, FirmVulLinker achieves higher precision with substantially lower false-positive and false-negative rates. Notably, it identifies and reproduces 53 previously undisclosed N-day vulnerabilities in firmware images not listed as affected at the time of public disclosure, effectively extending the known impact scope. Our results demonstrate that FirmVulLinker enables scalable, high-fidelity homologous vulnerability analysis, offering a new perspective on understanding cross-firmware vulnerability patterns in the IoT ecosystem. Full article

Polyethylene glycol (PEG) is among the most intensively researched and applied polymers, exhibiting a very wide range of industrial, pharmaceutical, and biomedical applications. The strongest and most highly diagnostic absorbance in the FTIR spectrum of PEG and of PEG-containing polyurethanes, is the ether C-O-C stretching absorbance, which consistently appears as a triple-peak absorbance in a semicrystalline state. Surprisingly, this phenomenon has very seldom been mentioned or elaborated, and no direct structural diagnostic FTIR assignment has been determined for each component of the triple-peak. The present research conclusively demonstrates that the left-side and right-side components of the triple-peak are assigned to the chain-fold regions and the extended-chain regions of the crystallized chains, respectively, while the strong-wide central component is assigned to the randomly oriented chains in the amorphous phase of the semicrystalline PEG. The present demonstration was facilitated via the synthesis of a highly oriented fibrillar polyurethane block-copolymer, exclusively containing extended-chain-crystallized PEG soft-segments, obtained through dense hard-segment crosslinking under vigorous unidirectional shear-stress continuously applied during the synthesis. The present research results enable us to directly relate the FTIR spectra of PEG and block copolymers synthesized thereof, to their crystallization mechanisms and chain conformations, thus facilitating the development of improved industrial processing methods. Full article

Plastic pollution poses significant environmental challenges due to its persistence and contribution to the microplastic formation, with polyethylene being among the materials more abundantly found. Understanding how different artificial weathering protocols influence the degradation of plastics is crucial for assessing their environmental impact. This study investigates the effects of three distinct artificial weathering protocols—continuous UV-A irradiation (M_L), cyclic UV-dark exposure (M_C[L→D]), and sequential UV-dark phase (M_L→D)—on the physicochemical properties of plastics, using oxo-low-density polyethylene as the model material. Surface oxidation, measured by quantification of the carbonyl index, was most pronounced under the M_C[L→D] protocol despite the shortest time of overall UV exposure, indicating that oxidative reactions continue during the dark phases. Vinyl group formation, however, required continuous or cyclic UV exposure, highlighting the critical role of light in this chemical process. Alterations in the surface hydrophilicity, measured by contact angle, and changes in molecular weight were quantified and found to closely link to the weathering conditions, with increased oxidations enhancing the surface hydrophilicity and the chain scission balanced by crosslinking with extended UV durations. These findings emphasize the importance of weathering protocols when trying to simulate conditions in the lab that are closer to the ones in the environment to understand plastic degradation mechanisms. Biodegradation experiments with Rhodococcus rhodochrous demonstrated that weathered oxo-LDPE samples with higher surface oxidation levels (ΔCI > 1) supported an increased CO₂ production by Rhodococcus rhodochrous, with the M_C[L→D]—360 h protocol yielding the highest biodegradation rates—31–43% higher than the control. Full article

To enhance the high-temperature resistance of silicone rubber and meet the application requirements of flexible conductive silicone rubber under elevated temperature conditions, this study adopts a chemical modification strategy by introducing phenyl groups into the molecular chains of silicone rubber to improve its thermal resistance. High-phenyl-content hydroxyl-terminated silicone oil (MPPS) was used as the polymer backbone, and vinylmethyldimethoxysilane (VDMS) served as the chain extender. Through a silanol condensation reaction, vinylmethylphenyl polysiloxane (VMPPS) with a crosslinkable structure was synthesized, providing reactive sites for subsequent vulcanization and molding. Subsequently, needle-like silver-coated glass fiber (AGF) conductive fillers were prepared via a green and environmentally friendly electroless silver plating method. These fillers were incorporated into the phenyl polysiloxane matrix to impart electrical conductivity to the phenyl silicone rubber while synergistically enhancing its thermal resistance. Finally, thermally resistant conductive silicone rubber was fabricated through high-temperature vulcanization, and the key properties of the material were systematically characterized. The synthesized phenyl polysiloxane exhibited a number-averaged molecular weight of up to 181,136, with a PDI of 2.43. When the loading of AGF reached 25 phr, the phenyl silicone rubber composite achieved the electrical percolation threshold, exhibiting a conductivity of 7.12 S/cm. With a further increase in AGF content to 35 phr, the composite demonstrated excellent thermal stability, with a 5% weight loss temperature of 478 °C and a residual mass of 37.36% at 800 °C. Moreover, after thermal aging at 100 °C for 72 h, the conductivity degradation of the phenyl silicone rubber was significantly lower than that of commercial silicone rubber, indicating outstanding electrical stability. This study provides an effective approach for the application of flexible electronic materials under extreme thermal environments. Full article

This study explores the use of propylene oxide-modified ethylenediamine (PPO-EDA) as a novel crosslinker and chain extender in polyurethane (PU) adhesives. PPO-EDA was synthesized and compared with N,N’-dimethylethylenediamine (DMEDA) to assess its impact on mechanical properties and adhesion performance. Key parameters such as NCO conversion, tensile strength, and lap shear strength were thoroughly evaluated. The results demonstrated that incorporating PPO-EDA significantly improved NCO conversion and crosslink density, leading to notable enhancements in tensile strength and elastic modulus compared to DMEDA. Lap shear tests further revealed superior adhesion performance in PPO-EDA-modified PU adhesives, particularly on amine silane-treated steel substrates, where lap shear strength consistently outperformed other samples. This improved performance was attributed to PPO-EDA’s dual role as a chain extender and crosslinker, which strengthened the adhesive’s structural integrity. This study underscores the effectiveness of PPO-EDA as a modifier for enhancing both mechanical and adhesive properties in PU-based adhesives, offering a promising solution for optimizing high-performance adhesives in automotive and industrial applications. Full article

This study successfully developed a bio-based, photocurable, anionic–nonionic dual-functional chain extender, and sulfonated cardanol-based polyethylene glycol (SCP), derived from renewable resources—cardanol and polyethylene glycol—for application in waterborne polyurethane dispersions (WPUDs). Utilizing SCP as a chain extender, WPUDs were prepared through a typical acetone process with poly(butylene adipate) (PBA), isophorone diisocyanate (IPDI), and ethylene diamine (EDA) at a constant NCO/OH ratio of 1:1. This research focused on the effects of polyethylene glycol molecular weight and SCP dosage on the particle size, stability, and film-forming properties of the WPUD. Optimal dispersion stability and film-forming performance were achieved with a polyethylene glycol molecular weight of 1500 and a PBA to SCP molar ratio of 4:1, yielding a particle size of 0.326 ± 0.010 μm and excellent storage stability over six months. The resulting WPU coatings exhibited a tensile strength of 11.4 MPa, which increased to 16.8 MPa after UV irradiation owing to the formation of a semi-interpenetrating network via the photopolymerization of cardanol’s unsaturated side chains. UV cross-linking also enhanced water resistance, reducing the water absorption rate (WAR) from 18.68% to 4.21% and the water vapor transmission rate (WVTR) from 6.59 × 10⁻⁵ g·m⁻¹·Pa⁻¹·d⁻¹ to 2.26 × 10⁻⁵ g·m⁻¹·Pa⁻¹·d⁻¹, while also improving thermal stability. These findings demonstrate that SCP offers a sustainable and effective solution for developing high-performance WPU coatings. Full article

Increasing of rubber content in isotactic polypropylene/ethylene–propylene rubber (iPP/EPR) alloys can extend the applications of this kind of polyolefin. The EPR content and phase structure of isotactic polypropylene multicomponents have great effect on the viscoelasticity and mechanical properties. iPP/EPR in-reactor alloys with a high EPR content were obtained through the in situ crosslinking of EPR chains with α,ω-diene. The morphological observation results indicate that the crosslinked iPP/EPR in-reactor alloys have a good spherical shape with clean and rough external surfaces. The high EPR content is finely dispersed in the crosslinked iPP/EPR alloys in areas ranging in size from tens of nanometers to several micrometers, which implies that a sufficient crosslinking degree of EPR chains can effectively prevent their aggregation and restrict macro-phase separation. The rheological results show a clear plateau in the terminal region, which reveals an entangled polymer chain network in the crosslinked iPP/EPR alloys. The well-dispersed EPR and the bi-continuous phase structure have a great effect on the mechanical properties of the isotactic polypropylene multicomponent which were assessed. Full article

In this work, we present basic research on developing thermogel carriers containing high amounts of model antibody immunoglobulin G (IgG) with potential use as injectable molecules. The quantities of IgG loaded into the gel were varied to evaluate the possibility of tuning the dose release. The gel materials were based on blends of thermoresponsive and degradable ABA-type block copolymers composed of poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (PLGA–PEG–PLGA) or poly(lactide-co-caprolactone)-b-poly(ethylene glycol)-b-(lactide-co-caprolactone) (PLCL–PEG–PLCL). Primarily, the gels with various amounts of IgG were obtained via thermogelation, where the only factor inducing gel formation was the change in temperature. Next, to control the gels’ mechanical properties, degradation rate, and the extent of antibody release, we have tested two approaches. The first one involved the synergistic physical and chemical crosslinking of the copolymers. To achieve this, the hydroxyl groups located at the ends of the PLGA–PEG–PLGA chain were modified into acrylate groups. In this case, the thermogelation was accompanied by chemical crosslinking through the Michael addition reaction. Such an approach increased the dynamic mechanical properties of the gels and simultaneously prolonged their decomposition time. An alternative solution was to suspend crosslinked PEG–polyester nanoparticles loaded with IgG in a PLGA–PEG–PLGA gelling copolymer. We observed that loading IgG into thermogels lowered the gelation temperature (T_GEL) value and increased the storage modulus of the gels, as compared with gels without IgG. The prepared gel materials were able to release the IgG from 8 up to 80 days, depending on the gel formulation and on the amount of loaded IgG. The results revealed that additional, chemical crosslinking of the thermogels and also suspension of particles in the polymer matrix substantially extended the duration of IgG release. With proper matching of the gel composition, environmental conditions, and the type and amount of active substances, antibody-containing thermogels can serve as effective IgG delivery materials. Full article

Tremendously negative effects have been generated in recent decades by the continuously increasing production of conventional plastics and the inadequate management of their waste products. This demands the production of materials within a circular economy, easy to recycle and to biodegrade, minimizing the environmental impact and increasing cost competitiveness. Bioplastics represent a sustainable alternative in this scenario. However, the replacement of plastics must be addressed considering several aspects along their lifecycle, from bioplastic processing to the final application of the product. In this review, the effects of using different additives, biomass sources, and processing techniques on the mechanical and thermal behavior, as well as on the biodegradability, of bioplastics is discussed. The importance of using bioplasticizers is highlighted, besides studying the role of surfactants, compatibilizers, cross-linkers, coupling agents, and chain extenders. Cellulose, lignin, starch, chitosan, and composites are analyzed as part of the non-synthetic bioplastics considered. Throughout the study, the emphasis is on the use of well-established manufacturing processes, such as extrusion, injection, compression, or blow molding, since these are the ones that satisfy the quality, productivity, and cost requirements for large-scale industrial production. Particular attention is also given to fused deposition modeling, since this additive manufacturing technique is nowadays not only used for making prototypes, but it is being integrated into the development of parts for a wide variety of biomedical and industrial applications. Finally, recyclability and the commercial requirements for bioplastics are discussed, and some future perspectives and challenges for the development of bio-based plastics are discussed, with the conclusion that technological innovations, economic incentives, and policy changes could be coupled with individually driven solutions to mitigate the negative environmental impacts associated with conventional plastics. Full article

In recent years, there has been increasing interest in developing novel materials based on natural biopolymers as a renewable alternative to petroleum-based plastics. The availability of proteins derived from agricultural by-products, along with their favourable properties, has fostered a renewed interest in protein-based materials, promoting research in innovative technologies. In this study, we propose the use of rapeseed protein-rich meal as the main ingredient for the preparation of novel sustainable materials combining excellent environmental properties such as biodegradability and renewability. The application of sustainable products in the present high-tech society requires the modification of the basic native properties of these natural compounds. The original route proposed in this paper consists of preparation via the compression moulding of flexible biomaterials stabilized by crosslinkers/chain extenders. An investigation of the effects of different denaturing and disulfide bond reducing agents, crosslinkers, and preparation conditions on the material mechanical behaviour demonstrated that the novel materials have appreciable strength and stiffness. The results show the potential of utilizing full meal from vegetable by-products to prepare protein-based materials with guaranteed ecofriendly characteristics and mechanical properties adequate for specific structural applications. Full article