Search Results (333)

Kiwifruit (Actinidia spp.) is a globally important economic fruit with high nutritional value. Fruit peelability, defined as the mechanical ease of separating the peel from the fruit flesh, is a critical quality trait influencing consumer experience and market competitiveness and has emerged as a critical breeding target in fruit crop improvement programs. The present review systematically synthesized existing studies on kiwifruit peelability, and focused on its evolutionary trajectory, genotypic divergence, quantitative evaluation, possible underlying mechanisms, and artificial manipulation strategies. Kiwifruit peelability research has advanced from early exploratory studies in New Zealand (2010s) to systematic investigations in China (2020s), with milestones including the development of evaluation metrics and the identification of genetic resources. Genotypic variation exists among kiwifruit genera. Several Actinidia eriantha accessions and the novel Actinidia longicarpa cultivar ‘Guifei’ exhibit superior peelability, whereas most commercial Actinidia chinensis and Actinidia deliciosa cultivars exhibit poor peelability. Quantitative evaluation highlights the need for standardized metrics, with “skin-flesh adhesion force” and “peel toughness” proposed as robust, instrument-quantifiable indicators to minimize operational variability. Mechanistically, peelability is speculated to be governed by cell wall polysaccharide metabolism and phytohormone signaling networks. Pectin degradation and differential distribution during fruit development form critical “peeling zones”, whereas ethylene, abscisic acid, and indoleacetic acid may regulate cell wall remodeling and softening, collectively influencing skin-flesh adhesion. Owing to the scarcity of easy-to-peel kiwifruit cultivars, artificial manipulation methods, including manual peeling benchmarking, lye treatment, and thermal peeling, can be employed to further optimize kiwifruit peelability. Currently, shortcomings include incomplete genotype-phenotype characterization, limited availability of easy-peeling germplasms, and a fragmented understanding of the underlying mechanisms. Future research should focus on methodological innovation, germplasm development, and the elucidation of relevant mechanisms. Full article

Developing multifunctional wound dressings with excellent mechanical properties, strong tissue adhesion, and efficient antibacterial activity is crucial for promoting wound healing. This study prepared a novel nanocomposite hydrogel dressing based on sodium alginate-polyacrylic acid dual crosslinking networks, incorporating tannic acid-coated cellulose nanocrystals (TA@CNC) and in-situ reduced silver nanoparticles for multifunctional enhancement. The rigid CNC framework significantly improved mechanical properties (elastic modulus of 146 kPa at 1 wt%), while TA catechol groups provided excellent adhesion (36.4 kPa to pigskin, 122% improvement over pure system) through dynamic hydrogen bonding and coordination interactions. TA served as a green reducing agent for uniform AgNPs loading, with CNC negative charges preventing particle aggregation. Antibacterial studies revealed synergistic effects between TA-induced membrane disruption and Ag⁺-triggered reactive oxygen species generation, achieving >99.5% inhibition against Staphylococcus aureus and Escherichia coli. The TA@CNC-regulated porous structure balanced swelling performance and water vapor transmission, facilitating wound exudate management and moist healing. This composite hydrogel successfully integrates mechanical toughness, tissue adhesion, antibacterial activity, and biocompatibility, providing a novel strategy for advanced wound dressing development. Full article

In this study, the influences of natural fibres (sugarcane bagasse (SB) and sawdust (SD)) on the material properties of polybutylene succinate (PBS) prepared through melt compounding were investigated. The study further evaluated the effects of incorporating halloysite nanotubes (HS) and expandable graphite (EG) on the properties of PBS/SD and PBS/SB binary and PBS/SB/SD hybrid composites. The morphological analysis indicated poor interfacial adhesion between PBS and the fibres. The obtained findings indicated enhancements in the complex viscosity of PBS in the presence of natural fibres, and further improvements in the presence of HS and EG. The stiffness of PBS hybrid composites also increased upon the addition of HS and EG. Moreover, the crystallization temperatures of PBS increased in the presence of fillers, with EG showing better nucleation efficiency. However, the mechanical properties (toughness and impact resilience) decreased due to the increased stiffness of the composites and the poor interfacial adhesion between the matrix and the fillers, indicating the need to pre-treat the fibres to enhance compatibility. Overall, the material properties of PBS/SD/SB hybrid composites were enhanced by incorporating HS and EG at low concentrations. Full article

Fe³⁺-incorporated hydrogels are particularly valuable for wearable devices due to their tunable mechanical properties and ionic conductivity. However, conventional immersion-based fabrication fundamentally limits hydrogel performance because of heterogeneous ion distribution, ionic leaching, and scalability limitations. To overcome these challenges, we report a novel one-pot strategy where controlled amounts of Fe³⁺ are directly added to polyacrylamide-sodium acrylate (PAM-SA) precursor solutions, ensuring homogeneous ion distribution. Combining this with Photoinduced Electron/Energy Transfer Reversible Addition–Fragmentation Chain Transfer (PET-RAFT) polymerization enables efficient hydrogel fabrication under open-vessel conditions, improving its scalability. Fe³⁺ concentration achieves unprecedented modulation of mechanical properties: Young’s modulus (10 to 150 kPa), toughness (0.26 to 2.3 MJ/m³), and strain at break (800% to 2500%). The hydrogels also exhibit excellent compressibility (90% strain recovery), energy dissipation (>90% dissipation efficiency at optimal Fe³⁺ levels), and universal adhesion to diverse surfaces (plastic, metal, PTFE, and cardboard). Finally, these Fe³⁺-incorporated hydrogels demonstrated high effectiveness as strain sensors for monitoring finger/elbow movements, with gauge factors dependent on composition. This work provides a scalable, oxygen-tolerant route to tunable hydrogels for advanced wearable devices. Full article

Zwitterionic hydrogels have emerged as eco-friendly anti-fouling materials owing to their superior hydration-mediated resistance to biofouling. Nevertheless, their practical utility remains constrained by intrinsically poor mechanical robustness. Herein, this study proposes a novel strategy to develop novel tough zwitterionic hydrogels by freezing the gels’ polymer network. As a proof of concept, a zwitterionic hydrogel was synthesized via copolymerization of hydrophobic monomer phenyl methacrylate (PMA) and hydrophilic cationic monomer N-(3-dimethylaminopropyl) methacrylamide (DMAPMA), followed by post-oxidation to yield a zwitterionic structure. At service temperature, the rigid and hydrophobic PMA segments remain frozen, while the hydrophilic zwitterionic units maintain substantial water content by osmotic pressure. Synergistically, the zwitterionic hydrogel achieves robust toughness and adhesiveness, with high rigidity (66 MPa), strength (4.78 MPa), and toughness (2.53 MJ/m³). Moreover, the hydrogel exhibits a distinct temperature-dependent behavior by manifesting softer and more stretchable behavior after heating, since the thawing of the gel network at high temperatures increases segmental mobility. Therefore, it achieved satisfactory adhesiveness to substrates (80 kPa). Additionally, the hydrogel demonstrated remarkable anti-fouling performance, effectively suppressing biofilm formation and larval attachment. In summary, this work opens up promising prospects for the development of zwitterionic hydrogels with high application potential. Full article

This study investigates the effect of the surface functionalization of tungsten disulfide (WS₂) nanoparticles with aminoacetic acid (glycine) on the structure, curing behavior, and mechanical performance of epoxy nanocomposites. Aminoacetic acid, as a non-toxic, bio-based modifier, enables a sustainable approach to producing more efficient nanofillers. Functionalization, as confirmed by FTIR, EDS, and XRD analyses, led to elevated surface polarity and greater chemical affinity between WS₂ and the epoxy matrix, thereby promoting uniform nanoparticle dispersion. The strengthened interfacial bonding resulted in a notable decrease in the curing onset temperature—from 51 °C (for pristine WS₂) to 43 °C—accompanied by an increase in polymerization enthalpy from 566 J/g to 639 J/g, which reflects more extensive crosslinking. The SEM examination of fracture surfaces revealed tortuous crack paths and localized plastic deformation zones, indicating superior fracture resistance. Mechanical testing showed marked improvements in flexural and tensile strength, modulus, and impact toughness at the optimal WS₂ loading of 0.5 phr and a 7.5 wt% aminoacetic acid concentration. The surface-modified WS₂ nanoparticles, which perform dual functions, not only reinforce interfacial adhesion and structural uniformity but also accelerate the curing process through chemical interaction with epoxy groups. These findings support the development of high-performance, environmentally sustainable epoxy nanocomposites utilizing amino acid-modified 2D nanofillers. Full article

This study discusses the frictional wear performance of three 3D-printed materials, acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and high-impact polystyrene (HIPS), while evaluating different layer thickness levels. The materials were subjected to wear volume and rate tests by ball-on-disc wear tests at various thickness levels (0.1, 0.2, and 0.3 mm) and sliding distances. Lastly, SEM analysis was carried out to study the wear tracks and debris developed during the testing. Quantitatively, ABS maintained a mean wear volume below 0.15 mm³ across all test conditions (e.g., 0.05 ± 0.01 mm³ at 0.1 mm layer thickness and 150 m sliding distance), whereas PLA and HIPS recorded much higher averages of 1.5 mm³ and 3.0 mm³, respectively. With the increase in layer thickness, which caused an upward trend in the obtained results, the wear volume of the investigated materials also increased. ABS exhibited the smallest material loss of all three polymers; for example, at 0.1 mm layer thickness and a 150 m sliding distance, the mean wear volume was only 0.05 mm³, and even under the harshest condition tested (0.3 mm layer thickness, 300 m), the value remained below 0.15 mm³. PLA and HIPS showed higher wear volumes, while HIPS had the lowest resistance among the three materials. The multifunctional wear behavior difference contributed by material type was 59.76%, as shown through ANOVA, and that by layer thickness was 21.32%. Among the parameters investigated, material type had the largest control in wear behavior due to inherent variation in the structural characteristics of the material such as interlayer adhesion, toughness, and brittleness. For instance, the amorphous nature of ABS and its good layer adhesion provided significantly superior wear resistance compared to the brittle PLA and the poorly adhered HIPS. It is highlighted in this research that selecting appropriate material and layer thickness combinations can improve the durability of 3D-printed components. Full article

This study presents colorless polyimides (PIs) suitable for use as plastic substrates in flexible displays, designed to be compatible with controlled soft adhesion and easy delamination (temporary adhesion) processes. For this purpose, we focused on a PI system derived from norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic dianhydride (CpODA) and 2,2′-bis(trifluoromethyl)benzidine (TFMB). This system was selected with the aim of exhibiting excellent optical transparency and low linear coefficient of thermal expansion (CTE) properties. However, fabricating this PI film via the conventional two-step process was challenging because of crack formation. In contrast, modified one-pot polymerization at 200 °C using a combined catalyst resulted in a homogeneous solution of PI with an exceptionally high molecular weight, yielding a flexible cast film. The solubility of PI plays a crucial role in its success. This study delves into the mechanism behind the significant catalytic effect on enhancing molecular weight. The CpODA/TFMB PI cast film simultaneously achieved very high optical transparency, an extremely high glass transition temperature (T_g = 411 °C), a significantly low linear coefficient of thermal expansion (CTE = 16.7 ppm/K), and sufficient film toughness, despite the trade-off between low CTE and high film toughness. The CpODA/TFMB system was modified by copolymerization with minor contents of another cycloaliphatic tetracarboxylic dianhydride, 5,5′-(1,4-phenylene)-exo-bis(hexahydro-4,7-methanoisobenzofuran-cis-exo-1,3-dione) (BzDAxx). This approach was effective in improving the film toughness without sacrificing the low CTE and other target properties. The peel strengths (σ_peel) of laminates comprising surface-modified glass substrates and various colorless PI films were measured to evaluate the compatibility with the temporary adhesion process. Most colorless PI films studied were found to be incompatible. Additionally, no correlation between σ_peel and PI structure was observed, making it challenging to identify the structural factors influencing σ_peel control. Surprisingly, a strong correlation was observed between σ_peel and CTE of the PI films, suggesting that the observed solid–solid lamination is closely linked to the unexpectedly high surface mobility of the PI films. The laminate using CpODA(90);BzDAxx(10)/TFMB copolymer exhibited suitable adhesion strength for the temporary adhesion process, while meeting other target properties. The modified one-pot polymerization method significantly contributed to the development of colorless PIs suitable for plastic substrates. Full article

Reinforced concrete structures are prone to the development of microcracks during service. In this study, a composite-modified epoxy potting adhesive was formulated using nano-TiO₂, carboxyl-terminated butadiene nitrile liquid rubber (CTBN), and the reactive diluent D-669. The mechanical properties and effectiveness of this composite adhesive in repairing oblique cracks were systematically evaluated and compared with those of single-component-modified epoxy adhesives. Key material parameters influencing the performance of oblique crack repair were identified, and the underlying repair mechanisms were analyzed. Based on these findings, a theoretical formula for calculating the shear-bearing capacity of beams with repaired web reinforcement was proposed. Experimental results demonstrated that compared to single-component-modified epoxy resin, the optimally formulated composite adhesive improved the tensile strength, elongation at break, and bond strength by 4.07–21.16 MPa, 13.28–20.4%, and 1.05–3.79 MPa, respectively, while reducing the viscosity by 48–872 mPa·s. The viscosity of the adhesive was found to play a critical role in determining the repair effectiveness, with toughness enhancing the crack resistance and bond strength contributing to the structural stiffness recovery. The adhesive effectively penetrated the steel–concrete interface, forming a continuous bonding layer that improved energy dissipation and significantly enhanced the load-bearing capacity of the repaired beams. Full article

To obtain waterborne polymer-modified emulsified asphalt materials with better comprehensive performance, waterborne polymer modifiers including waterborne epoxy resin (WER)-reinforced styrene–butadiene–styrene block copolymer (SBS), waterborne acrylate (WA) or styrene butadiene rubber (SBR) emulsion were prepared. The mechanical strength, toughness, adhesion and impact resistance of these waterborne polymers were evaluated. Furthermore, the correlation between the performance indicators of the waterborne polymers was analyzed. Based on Fourier transform infrared (FTIR) spectroscopy and thermogravimetric (TG) analysis, the mechanism of WER-modified SBS and WA was characterized. The results show that adding 10%–15% WER can significantly improve the mechanical properties of the waterborne polymer. The performances of modified SBS and WA are better than that of modified SBR. When the content of WER is 10%, the tensile strength, elongation at break and pull-off strength of WER-modified SBS and WA are 4.80–6.38 MPa, 476.3%–579.6% and 1.62–1.70 MPa, respectively. The mechanical strength and breaking energy of the waterborne polymers show a significant linear correlation with their application properties such as adhesion, bonding and impact resistance. FTIR and TG analyses indicate that WER-modified SBS or WA prepared via emulsion blending undergo primarily physical modifications, enhancing thermal stability while promoting crosslinking and curing. Full article

Type IV hydrogen storage cylinders are pivotal for high-pressure hydrogen storage and transportation, offering advantages such as lightweight design, high hydrogen storage density, and cost efficiency. Polyamide 6 (PA6) has emerged as a promising liner material due to its excellent mechanical strength, chemical resistance, and gas barrier properties. However, challenges remain, including high hydrogen permeability and insufficient mechanical performance under extreme temperature and pressure conditions. This review systematically summarizes recent advances in modification strategies to enhance PA6’s suitability for Type IV hydrogen storage cylinders. Incorporating nanofillers (e.g., graphene, montmorillonite, and carbon nanotubes) significantly reduces hydrogen permeability. In situ polymerization and polymer blending techniques improve toughness and interfacial adhesion (e.g., ternary blends achieve a special increase in impact strength). Multiscale structural design (e.g., biaxial stretching) and process optimization further enhance PA6’s overall performance. Future research should focus on interdisciplinary innovation, standardized testing protocols, and industry–academia collaboration to accelerate the commercialization of PA6-based composites for hydrogen storage applications. This review provides theoretical insights and engineering guidelines for developing high-performance liner materials. Full article

A transdermal drug delivery system based on hydrogel patches was explored, leveraging their sustained release properties and biocompatibility. Despite these advantages, conventional hydrogels often lack proper adhesion to the skin, limiting their practical application. To address this issue, we designed a skin-adhesive hydrogel using a polyacrylamide (PAM)/polydopamine (PDA) dual-network structure. The matrix combines the mechanical toughness of PAM with the strong adhesive properties of PDA, derived from mussel foot proteins, enabling firm tissue attachment and robust performance under physiological conditions. To demonstrate its applicability, the hydrogel was integrated with poly(lactic-co-glycolic acid) (PLGA) nanoparticles encapsulating the hydrophobic antioxidant vitamin E as a model compound. The resulting PAM/PDA@VitE hydrogel system exhibited improved swelling behavior, high water retention, and prolonged release of α-tocopherol. These results suggest that the PAM/PDA hydrogel platform is a versatile vehicle not only for vitamin E, but also for the transdermal delivery of various cosmetic and therapeutic agents. Full article

This study focuses first on the synthesis through an aza-Michael addition reaction of original linear diamine prepolymers and original amine/acrylate thermoset adhesives, and second on their thermal, mechanical and adhesion characterization. The major advantage of the aza-Michael addition reaction is that it takes place at room temperature, without a solvent and without a catalyst. Using the aza-Michael addition reaction, linear secondary diamine prepolymers were first synthesized with a control of the molecular weight, ranging from 867 to 1882 g mol⁻¹. Then, aza-Michael reactions of diamine prepolymers with three different acrylates allowed the synthesis of new amine/acrylate thermoset adhesives. All the thermoset adhesives were characterized by rheology and thermal analysis, leading, once the crosslinking aza-Michael reaction had occurred, to soft thermoset networks with glass transition temperatures ranging from −23 to −8 °C, gel point times ranging from 40 min to 4 h, and a polar component of the surface energy ranging from 3 to 17 mJ m⁻². Functionality of the acrylates directly influences the crosslinking rate, and a decreasing master curve is obtained when reporting crosslinking rate versus gel point time. Crosslinking density is controlled by the diamine prepolymer chain length. In a second step, thermoset adhesives were applied as thin films between two galvanized steel plates, and adhesion properties were evaluated through a lap-shear test. Results showed that the adhesive strength increases as the dynamic viscosity and molecular weight of the diamines prepolymer increases. Increasing the diamines prepolymer chain length results in an increase in strain at break, a decrease in the shear modulus, and a decrease in the maximum lap-shear strength. It is also observed that the adhesive strength decreases when the adhesive film thickness increases. Moreover, thermoset adhesives with high polarity and a surface energy similar to the surface energy of the substrate will favor high adhesion and a better adhesive strength of the assembly. Lastly, the nature of the acrylates and diamines prepolymer chain length allow tuning a wide range of adhesive strength and toughness of these original soft thermoset adhesives. Full article

The purpose of this study was to clarify the physical durability of a diamond-like carbon (DLC) thin film coated on pure titanium. The titanium surface of the abutment does not have sufficient toughness to prevent an increase in surface roughness or damage when the implant is scaled using a professional mechanical implement. The scaling process used for the removal of the dental plaque adhered to the abutment surface could increase the potential for the deposition of oral microorganisms and the accumulation of plaque, which increase the risk of peri-implantitis. A DLC thin film is biocompatible material that is known for its toughness, including extreme hardness, high abrasion resistance, chemical inertness, and high corrosion resistance. Protecting the abutment surface with the application of a DLC might prevent plaque adhesion due to its non-stick property. There was little change in the surface roughness of titanium samples to which DLC surface protection had been applied when the surface of the sample was scratched with a stainless steel scalar more than a thousand times. When cleaning the surface of pure titanium samples, the surface roughness significantly increased. DLC thin films are effective for the prevention the surface roughness of pure titanium implants from being increased when the conventional cleaning of the surface of the implant is performed. Full article

Epoxy resins have been extensively employed in cultural heritage conservation as both adhesive and reinforcement materials owing to their exceptional bonding strength, relatively low toxicity, and cost-effectiveness. This review initially outlines the fundamental material characteristics of epoxy resins and subsequently examines their contemporary applications in artifact restoration. Subsequently, it synthesizes the research advancements documented over the past two decades, with a focus on critical challenges associated with their application in cultural heritage preservation, including susceptibility to aging, inherent brittleness, and prolonged curing time. The corresponding modification strategies are systematically examined, including strategies for aging resistance enhancement, toughness improvement, and rapid-curing techniques. Finally, potential future directions for epoxy resin applications in conservation are critically evaluated. This review provides a comprehensive analysis of epoxy resins’ performance and modification methodologies, thereby offering valuable insights to guide future research on its application in cultural heritage conservation. Full article