Adhesive Shear Strength Research Articles

Cold-spray repair of CuCrZr crystallizers: Effect of substrate pretreatment

Cold spraying is a promising technique for repairing damaged CuCrZr crystallizers, and the interface between the repair coating and the substrate plays a critical role in determining the heat transfer efficiency of the repaired crystallizers. In this study, two coating/substrate interfaces were prepared through polishing and grit-blasting the CuCrZr substrate surface. Effect of substrate pretreatment on microstructure and performance of the CuCrZr coating was studied using electron backscatter diffraction, adhesive shear strength and thermal conduction tests. Results show that the surface preparation method does not affect the microstructure and hardness of the CuCrZr coating, but the coating sprayed on the grit-blasted substrate has a lower shear adhesive strength and heat conductivity than the coating sprayed on the polished substrate. This difference is attributed to the formation of a work hardening zone during the grit-blasting process. After releasing this work hardening by annealing at 500°C, the difference in heat conductivity then disappears, but the average shear adhesive strength of the annealed coating on the polished substrate is still higher than that on the grit-blasted substrate. Therefore, polishing the substrate could serve as a more viable option for the cold spray repair of CuCrZr crystallizers.

Bio-inspired anti-swelling amyloid-fiber lysozyme adhesive for rapid wound closure and hemostasis.

Instant adhesion to wet biological surfaces and reduced swelling of tissue adhesives are crucial for rapid wound closure and hemostasis. However, previous strategies to reduce swelling were always accompanied by a decrease in the tissue bonding strength of the adhesive. Moreover, the irreducibility of the covalent bonds in currently reported adhesives results in the adhesives losing their tissue adhesive ability. To tackle the challenge, a superior anti-swelling coacervate adhesive possessing fast self-healing properties through physical interactions (electrostatic interactions, hydrogen bonding) and chemical crosslinking (Schiff base reaction) was obtained with aldehyde-modified γ-PGA (γ-PGA-CHO), a natural lysozyme (LZM) and an amyloid fiber reduced lysozyme (RLZM). The instant shear adhesion strength and burst pressure tolerance of the adhesive on wet pig intestine reached 50.8 kPa (2.6 times that of CA glue) and 142.5 mmHg (5.9 times that of CA glue), and it maintained an adhesion strength of 37.4 kPa after exposure to the physical environment for 12 h and the swelling rate was only 34.0% underwater. The in vitro and in vivo experiments provided the coacervate adhesive with potential applicability for emergency rescue and wound care scenarios.

Shear Strength of Adhesives Based on Solvent Type, Aged, and LED-cured with Different Wavelengths: An In Vitro Study.

To evaluate the shear strength of adhesives based on the type of solvent (ethanol and acetone), aged and light-cured using light-emitting diode (LED) units with different wavelengths. Polywave and monowave LED units were employed for this in vitro study. Ninety bovine tooth samples were analyzed using OptiBond Universal adhesive (acetone) and single bond universal adhesive (ethanol). The samples underwent an aging process before being light-cured with different programs of polywave LED units (high-power, low-power, soft start) and monowave. Shear strength was measured using an Instron® Universal testing machine, with statistical analysis performed using ANOVA and the student's t-test. The adhesive with ethanol solvent, light-cured with polywave in high-power mode, achieved an average of 11.06 MPa, while low-power and soft start modes yielded 7.23 MPa and 10.82 MPa, respectively. The adhesive with acetone solvent, light-cured in high-power mode, had an average shear strength of 14.27 MPa, compared to 12.71 MPa in low-power mode and 12.92 MPa in soft start mode. No statistically significant differences were observed between the mean shear strengths of the groups treated with polywave and monowave LED units (p > 0.05). The shear strength of adhesives with ethanol and acetone solvents varies depending on the light-curing program used, but no significant differences were found between the solvents when cured with polywave and monowave LED units. The choice of solvent type and light-curing program may influence adhesion properties. A careful selection of solvent and light-curing techniques for adhesives can enhance the quality and durability of dental restorations, improving adhesion and reducing micro leakage. How to cite this article: Medina J, Orellana-Arauco H, Chacon-Gonzales D, et al. Shear Strength of Adhesives Based on Solvent Type, Aged, and LED-cured with Different Wavelengths: An In Vitro Study. J Contemp Dent Pract 2024;25(9):846-850.

Osseoconductive CaTi4-zZrz(PO4)6 Ceramics: Solutions Towards Nonunion, Osteoporosis, and Osteoarthrosis Conditions?

Transition (Ti, Zr) metal-substituted calcium hexaorthophosphate CaTi4-zZrz(PO4)6 coatings with an NaSICon structure were deposited by atmospheric plasma spraying (APS) onto Ti6Al4Veli substrates using a statistical design of experiments (SDE) methodology. Several coating properties were determined, including chemical composition, porosity, surface roughness, tensile adhesion strength, shear strength, and solubility in protein-free simulated body fluid (pf-SBF) and TRIS-HCl buffer solution. The biological performance evaluation involved cell proliferation and vitality studies and osseointegration tests of coated Ti6Al4Veli rods intramedullary implanted in sheep femora. After a 6 months observation time, a satisfactory gap-bridging potential was apparent as shown by a continuous, well-adhering layer of newly formed cortical bone. These tests suggest that the coatings possess a suitable osseoconductive potential and present an enhanced expression of bone growth-supporting non-collagenous proteins and cytokines, a high cell proliferation, spreading and vitality, and substantial osseointegration by strong bone apposition. The moderate intrinsic ionic conductivity of CaTi4-zZrz(PO4)6 compounds can be augmented by doping with highly mobile Na+ or Li+ ions to levels that suggest their use in electric bone growth stimulation (EBGS) devices, able to treat nonunion (pseudoarthrosis) and osteoporosis, and that may also support spinal stabilisation by vertebral fusion.

A Constant Filgotinib Delivery Adhesive Platform Based on Polyethylene Glycol (PEG) Hydrogel for Accelerating Wound Healing via Restoring Macrophage Mitochondrial Homeostasis.

Skin wound healingis often hindered bydisrupted mitochondrial homeostasis and imbalanced macrophage glucose metabolism, posing a critical challenge to improve patient outcomes. Developing new wound healing dressings capable of effectively regulating macrophage immune-metabolic functions remains a pressing issue. Herein, a highly adhesive polyethylene glycol (PEG) hydrogel loaded with the Janus kinase 1 (JAK1) inhibitor Filgotinib (Fil@GEL) is prepared to modulate macrophage metabolic reprogramming and restore normal mitochondrial function.Fil@GEL exhibits superior shear adhesion strength compared to commercially available tissue binder products, providing adequate adhesion for skin wound closure. Additionally, Fil@GEL exhibits the capacity to inhibit M1-type macrophage polarization by suppressing the JAK-STAT signaling pathway, and induces a metabolic shift in macrophages from aerobic glycolysis to oxidative phosphorylation, which results in decreased lactate production, reduced reactive oxygen species (ROS) levels, and the restoration of mitochondrial homeostasis. The Fil@GEL hydrogel significantly accelerates skin wound healing compared to the control group, reduces intra-wound inflammation, and promotes collagen regeneration. In summary, this highly adhesive hydrogel demonstrates exceptional performance as a drug carrier, exerting immunometabolic modulation through firm wound adhesion and sustained filgotinib release, underscoring its substantial potential as an effective wound dressing.

Rational Design of Hot‐Melt Biodegradable Tissue Adhesive for Bone Fracture Repair

ABSTRACTBiodegradable bone adhesives can be an effective alternative to metallic implants for stabilizing bone fractures, promoting healing, and restoring full function and mobility. Nonetheless, achieving strong adhesion to the bone under physiological conditions is complex. Herein, a polymer‐based hot‐melt biodegradable bone‐tissue adhesive was developed for bone fracture repair to provide strong bone adhesion in physiological (wet) conditions and is easy to apply. The incorporation of 3,4‐dihydroxyhydrocinnamic acid (HCA) and monobasic calcium phosphate monohydrate (MCPM) into the poly(ε‐caprolactone) (PCL) matrix via melt blending demonstrated successful adhesion of bovine bone slices under wet conditions. A mixture design of experiments was applied to optimize the adhesive formulation to maximize adhesion strength while minimizing the adhesive's melting temperature (Tm). The optimized composition of 50% PCL, 25% HCA, 25% MCPM achieved a Tm of 52°C ± 0.6°C and a lap shear adhesion strength of 294 ± 88 kPa after 30 min and 226 ± 51 kPa after 2 h of application. Time‐dependent oscillatory shear measurements revealed that HCA prolongs the setting time while MCPM reduces it. Furthermore, in vivo feasibility testing demonstrated successful adhesion of fractured bones. The hot‐melt adhesive represents a promising approach toward bone fracture repair.

Incorporation of Ceragenins into Medical Adhesives and Adhesive Scar Tape to Prevent Microbial Colonization Common in Healthcare-Associated Infections.

Background/Objectives: Healthcare-associated infections involving surgical sites, skin trauma, and devices penetrating the skin are a frequent source of increased expense, hospitalization periods, and adverse outcomes. Medical adhesives are often employed to help protect compromised skin from infection and to secure medical devices, but adhesives can become contaminated by pathogens, exposing wounds, surgical sites, and medical devices to colonization. We aimed to incorporate ceragenins, a class of antimicrobial agents, into silicone- and polyacrylate-based adhesives with the goal of reducing adhesive contamination and subsequent infections. Methods: Three adhesives were developed and evaluated for the release of ceragenins, antimicrobial efficacy, adhesive strength, and dermal irritation. Results: Elution profiles over two weeks showed a high initial release followed by steady, long-term release. Standard microbial challenges of the adhesives by methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, or Candida albicans demonstrated microbial reduction for 6 to 68 days. Lap shear adhesive strength was not reduced for polyacrylate adhesives containing ceragenins, and no dermal irritation was observed in an in vivo model. Conclusions: Ceragenin-containing adhesive materials appear well suited for prevention of bacterial and fungal infections associated with medical devices and bandages.

Designing the regularity of biodegradable copolyester for sustainable hot-melt adhesives: Adhesion, removability, and biodegradability

Recent research has increased in eco-friendly hot-melt adhesives as alternatives to conventional commercial hot-melt adhesives. However, there have been limitations in terms of removability and biodegradability. This study addresses these issues by designing a novel molecular structure for a single polymer, resulting in a sustainable hot-melt adhesive that offers strong adhesion, clear removability, and high biodegradability without additional additives. By varying the ratio of alcohol monomers 1,4-butanediol (BD) and ethylene glycol (EG) during polymerization, we synthesized poly(butylene adipate-co-butylene terephthalate-co-ethylene adipate-co-ethylene terephthalate) (PBEAT) with four block segments. We increased the open time by reducing the regularity of the molecular structure, controlling crystallization behavior, and inhibiting polymer chain packing. This improvement in wettability with the adherend allowed us to achieve a lap shear adhesion strength of 3.18 MPa. Additionally, we proposed a debonding mechanism based on the correlation between the crystallization temperature (Tc) block copolymer's and shear adhesion failure temperature (SAFT), demonstrating the removability of the prepared hot-melt adhesive. Finally, analyses of hydrolysis, enzymatic degradation, and biodegradation in compost confirmed that reduced crystallinity enhances biodegradability. PBE30AT, exhibiting the strongest adhesion strength, achieves complete degradation in compost within 20 days, faster than neat poly(butylene adipate-co-terephthalate) (PBAT). This research offers a novel and practical approach to enhancing the potential and expandability of sustainable adhesives by tailoring the molecular structure of the polymer.

Double-Sided Pressure-Sensitive Adhesive Materials under Human-Centric Extreme Environments.

Maintaining the adhesion strength of flexible pressure-sensitive adhesives (PSAs) is crucial for advanced applications, such as health monitoring. Sustainable mounting is critical for wearable sensor devices, especially under challenging surroundings such as low and high temperatures (e.g., polar regions or deserts), underwater and sweat environments (physical activity), and cyclical shear complex stresses. In this article, we consider the adhesive, mechanical, and optical properties of medical-grade double-sided PSAs by simulating extreme human-centric environments. Diverse temperature conditions, water and humidity exposures, and cyclical loads were selected and tested over long intervals, up to 28 days. We observed that high temperatures increased the shear adhesion strength due to the pore closing and expanding contact area between the adhesive layer and substrate. Conversely, low temperatures caused the adhesive layers to harden and reduce the adhesive strength. Immersion in salty and weakly acidic water and excessive humidity reduced adhesion as water interfered with the interfacial interactions. PSA films showed either adhesive or cohesive failure under extreme mechanical stresses and cyclical loading, which is also affected by the presence of various polar solvents. We demonstrated that the variable adhesive performance, mechanical properties, and optical transparency of pressure-sensitive materials can be directly related to changes in their morphologies, surface roughness, swelling state, and alternation of the mechanical contact area, helping to establish the broader rules of design for wearable human health monitoring sensors for the long-term application of wearable devices, sensors, and electrodes.

Bond line shear strength of structural wood adhesives at high temperatures up to wood carbonization – A classification approach

The European timber fire design code EN 1995-1-2 presently specifies that adhesives for timber construction products shall provide integrity throughout the intended fire exposure time, yet no test or requirement specifications are given. Contrary, in North America elevated temperature tests are mandatory and product standards for glued and cross laminated timber demand sufficient bond line shear strength up to 220 °C. This paper deals with block shear compression tests at ambient and elevated temperatures for development of a high temperature resistance classification system for structural wood adhesives. The investigations comprised 1200 specimens made from Norway spruce bonded with twelve brands from five adhesive families. Polycondensation (pcon) resins encompassed phenolic resorcinol formaldehyde, melamine urea formaldehyde and melamine formaldehyde adhesives. Polyaddition (padd) adhesives comprised five one-component polyurethanes and an emulsion polymer isocyanate. The focus was on the strength-temperature (fv-T) relationship of bonded and solid wood reference specimens at 180–270 °C. The pcon adhesives showed almost throughout a fv-T relationship close to solid wood up to 270 °C. Contrary, the padd adhesives revealed massive strength degradations vs. solid wood from 180 °C onwards. An adhesive test, evaluation and classification procedure with four classes T270 to T200 was derived. It is based on a comparison of the temperature-dependent shear strength decline in bonded samples vs. solid wood reference samples beyond 180 °C. Class T270 adhesives are proposed being suited for the linear charring model of EN 1995-1-2 as PRF adhesives without additional fire resistance testing of components deemed necessary today.

Biomass-derived epoxy resin and its application for high-performance natural fiber composites

The development of bio-based materials with superior comprehensive properties from biomass resources remains a significant challenge, providing an alternative to conventional petroleum-based materials. This study explores the lignin-derived vanillyl alcohol epoxy (VAE) resin-containing mono and di (m&d) epoxy structure as an adhesive to develop environment-friendly natural fiber-reinforced composites to reduce the carbon footprint. The synthesized m&dVAE containing mono and di-epoxidized (m&d) aromatic rings, when cured with 4, 4´-diaminodiphenyl methane (DDM) hardener, exhibits higher record tensile strength ∼124.0 ± 8.43 MPa and tensile modulus ∼2.88 ± 0.35 GPa compared to a commercial petroleum-based epoxy, diglycidyl ether bisphenol A (DGEBA) thermoset. Additionally, it demonstrated higher adhesion shear strength (∼19.16 ± 0.58 MPa) with cellulose nanofibers film than DGEBA. Moreover, fabricated green composite possesses excellent flexural strength of ∼203.72 ± 2.08 MPa and stiffness of ∼11.58 ± 0.38 GPa than the petroleum-based thermoset composite. The composite’s fracture surface morphology shows that the resin and fibers have good interfacial adhesion. Notably, the sustainable composite showed good hydrophobicity and an excellent heat-resistant index of 144.4°C. The m&dVAE resin can be an alternative to petroleum-based resins as an adhesive, and its environment-friendly sustainable composite could be a promising candidate to replace synthetic materials for high-performance structural applications.

Bonding and fracture properties of SPI-CNTs/epoxy adhesive on SPI-CNTs deposited CFRP composites

Adhesive bonding is frequently used to connect CFRP structures due to its lightweight, easy implementation and high production efficiency. However, the bonding performance of adhesive is far from satisfactory as dimension and complexity of CFRP structures increase. In this paper, a new bonding strategy for CFRP structures via introducing soy protein isolate modified carbon nanotubes (SPI-CNTs) both in the epoxy resin adhesive and on the bonding parts' surface is proposed. Results showed that SPI can effectively improve CNTs' dispersion on the two areas, notably enhancing the bonding performance of the adhesive. When 0.3 wt% SPI-CNTs was added in the adhesive, its adhesive shear strength increased to 12.76 MPa, which was 72 % higher than the unmodified CNTs/epoxy adhesive. Based on this concentration, the SPI-CNTs was deposited uniformly on the surface of the CFRP adherends via bath sonication and resulted in a maximum shear strength of 15.59 MPa, which was 22.2 % greater than the untreated ones. Based on the above condition, the Mode I fracture toughness G1c and the Mixed-Mode I/II fracture toughness Gc could reach a maximum of 0.31 and 0.44 N/mm respectively, which were 117 % and 97 % higher than the pure epoxy adhesive. The present work shows a new pathway for the effective bonding of CFRP structural components used in the aerospace industry.

Sulfur-modified polyurethane adhesives: Green synthesis process and disassembly-responsive characteristics

Polyurethane adhesives have been widely used in industrial production and daily life for their excellent properties. With the urgent need for social progress, the intelligent responsiveness of polyurethane adhesives has become more and more important. Here, we demonstrate a stimulus-responsive polyurethane adhesive. Starting from the structural design, sulfur (S8) is added into the polyurethane adhesive for the first time using the inverse vulcanized mechanism, and the controllable disassembly response of the polyurethane adhesive under the condition of thermal stimulation is realized. In addition, the stimulus response of the adhesive can also be activated through the permeation process of methoxide anion (CH3O−), and the rapid disassembly response property is displayed in the methanol solution of CH3ONa, to realize the recovery of the bonding substrate. Simultaneously, the implementation of the inverse vulcanized mechanism imparts the adhesive with a diminished water absorption swelling rate and heightened cross-link density. On the surface of the metal substrate, it shows excellent bonding properties, with a lap shear adhesion strength reaching 2.8 MPa. It is worth noting that the adhesive also exhibits excellent underwater durability. After 36 h of underwater soaking treatment, its adhesion can still be maintained at 2.4 MPa. This work reveals the mechanism of rapid disassembly of polyurethane adhesives at the molecular level. By density functional theory (DFT) calculation, it is found that the minimum bond energy of the S-S bond in a polyurethane adhesive system is 134 KJ·mol−1, and the disassembly response can be triggered by heating to 53.79℃. At the same time, the mechanism of the disassembly response induced by CH3O− is further analyzed using an electrostatic potential (ESP) diagram. This work utilizes sulfur (S8) and castor oil (CO) as raw materials, which can be sourced from industrial or agricultural by-products. It breaks away from traditional polyurethane adhesive preparation methods and offers a "green" strategy that can be synthesized through a solvent-free one-pot process, thus providing a new way of thinking about obtaining sustainable polymers from industrial and agricultural by-products.

Clathrate Hydrate-Solid Surface Adhesive Shear Strength Measurements on Carbon Steel Surfaces.

Oil and gas flowlines operating in subsea or cold terrestrial environments face the risk of forming hydrate deposits and plugs. The pressure differential across a hydrate plug can cause the plug to detach from the pipe wall and travel through the pipeline, potentially impacting a bend or inline equipment, causing damage or injury to personnel. Therefore, the hydrate-solid adhesive shear strength is of interest in estimating the maximum allowable differential pressure across a plug during depressurization procedures before the plug is likely to detach from the pipe wall. Quantifying the changes in adhesive shear strength with time and operational conditions is essential in estimating the potential of hydrate deposits to slough from the pipe wall. This work used a force meter with a cylindrical "pig-style" probe mounted to a single axis motorized test stand to measure the force required to dislodge model THF structure II hydrate plugs in carbon steel pipes. Profilometry measurements were used to quantify the mean surface roughness and relative peak frequency of the pipe surfaces. Contact angle measurements were performed of a water droplet on pristine, sanded, and corroded pipe surfaces immersed in nonpolar solvents. The adhesive shear strength of the hydrate plugs was measured for different subcoolings, solid surface roughness, and surface wettabilities. Subcooling was shown to impact the hydrate-solid adhesive shear strength, and a mixed adhesive/cohesive failure mechanism was observed at the highest subcooling tested. The surface roughness and wettability were also shown to influence the hydrate-solid adhesive shear strength, with readily wetting corroded and sanded carbon steel surfaces resulting in greater interface adhesive strength than the pristine carbon steel system. This is likely due to a Wenzel wetting mode at the interface, resulting in a higher ratio of actual to apparent wetted area as well as establishing a mechanical interlocking mechanism.

Comparative evaluation of the shear strength of orthodontic adhesives for fixation of brackets

Comparative evaluation of the shear strength of orthodontic adhesives for fixation of brackets

Investigation of the mechanical and thermal properties of epoxy adhesives reinforced by carbon nanotubes and silicon dioxide nanoparticles in single-lap joints

In this study, the shear strength and thermal properties of the adhesively bonded joints were investigated of adhesives reinforced with nanoparticles using carbon fiber-reinforced composite materials. The diglycidyl ether bisphenol A (DGEBA) was used as the epoxy resin. Single lap joint tests of 1% wt. Multi-walled carbon nanotubes (MWCNT) and 3, 5, and 7% wt. silicon dioxide (SiO2) nanoparticle-reinforced mixed adhesives were performed according to ASTM D5868 standards. The shear strengths of the mixed adhesives obtained by mixing at different ratios were compared with the epoxy resin. Upon conducting an analysis of the shear strengths of nanomaterials, results indicate that the incorporation of 1CNT + 3SiO2 in the nanomaterials showed the greatest improvement, with a 46% increase in shear strength. 1CNT + 5SiO2, 1CNT, and 1CNT + 7SiO2 showed increases of 32%, 14%, and 5%, respectively. The results of a tensile test indicate that pure epoxy exhibited a tensile strength of 5953 N, 1CNT, and 3SiO2, while the epoxy composite demonstrated a significantly higher tensile strength of 8738 N, along with an elongation of 0.72 mm. In addition, the morphology of fractured surfaces was examined by scanning electron microscopy (SEM). To investigate damage mechanisms, such as bridging, crack blunting, and branching of nanoparticles were observed. Characterization of epoxy resin and mixed MWCNT + SiO2 nanoparticles reinforced adhesives were also performed using Fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). Nanoparticles are settled between polymer chains, improving polymer chains’ motion and thermal properties.

Effect of Shear Loading Conditions on the Measured Strength of Ice Adhesion to Superhydrophobic Surfaces

Despite the significant interest of researchers, icing of aircraft, vehicles, ships, and equipment of offshore oil structures remains to be an urgent problem. This paper considers the factors that promote a decrease in the strength of the contact between ice and surfaces under an applied shear load. The main attention is focused on studying the influence of the rate of shear loading on the fracture of the interfacial contact between ice and superhydrophobic coatings. The strength of the adhesive contact under the conditions of controlled variations in the applied load is measured using a technique based on the detachment of ice from a surface under the influence of centrifugal force. The study is carried out for large ensembles of samples in the temperature range from −5 to −20°C, thereby making it possible to evaluate the influence of the quasi-liquid layer and the Rehbinder effect on a decrease in the shear adhesive strength. The results obtained indicate that the contact between ice and a superhydrophobic coating is fractured through a mixed viscous–brittle mechanism. In this case, a decrease in temperature or an increase in the loading rate causes a transition from the viscous to the brittle fracture. These results indicate a potential acceleration of ice shedding with an increase in the growth rate of the shear stress.

Carboxymethylated Lignin Reinforcement of SPI Adhesive: Enhancing Strength, Antimicrobial, and Flame-Retardant Properties without Excessive Alkali Introduction.

To address the challenges associated with formaldehyde emissions in engineered wood adhesives and simultaneously enhance adhesive properties related to water resistance, fire resistance, and mold resistance, a novel environmentally sustainable biomass-based adhesive was formulated. In this work, kraft lignin was carboxymethylated and then blended with the soy protein isolate (SPI)-based adhesive, the dry and wet shear strength of the plywood bonded by the resultant adhesive was enhanced from 1.10 and 0.63 MPa to 1.73 and 1.23 MPa, respectively, resulting in improvements of 157% and 195%. Carboxymethylated lignin (CML) significantly improved the mold resistance and flame-resistance residual rate of the adhesive and decreased the water absorption rate from 190% to 108%. Furthermore, the adhesive exhibits outstanding flame-retardancy, with self-extinguishing capability rendering it suitable for industrial production. In addition, we also evaluated the performances of resulting adhesives cured with different diepoxides and triepoxides, and the comparisons of the adhesive in this work to commercial urea glue and soy protein-based adhesives were conducted. To our delight, the SPI-10CML adhesive presented comparable or even improved performances, showing its promising practical applications such as for fire doors.

Multiscale analysis of hierarchical flax-epoxy biocomposites with nanostructured interphase by xyloglucan and cellulose nanocrystals

Natural biological systems feature hierarchical nanostructured architectures achieving high strength and toughness. In this work, the spontaneous adsorption of xyloglucan (XG) and cellulose nanocrystals (CNC) onto flax fabrics is considered to develop hierarchical interphases with improved interfacial adhesion in epoxy-based biocomposites. A multi-scale analysis is carried out, from the nano & micrometric scale with the characterization of fibre surface topography, work of adhesion and interfacial shear strength (IFSS) between flax fibres and epoxy resin, to the macroscopic scale with the transverse mechanical properties of biocomposites. At the fibre scale, XG and CNC increase the surface roughness of flax fibres, as well as their adhesion to epoxy resin with IFSS improved by 60 %, up to 22.3 MPa. At the composite scale, the treatments have a major influence on the cohesion of flax cell walls and microstructure of the biocomposites. Transverse tensile tests reveal both cohesive and adhesive interfacial failure.

Towards the icephobicity evolution of metallic surfaces affected by transitional wettability

In light of the escalating demands for ice protection related applications in diverse fields, including wind energy, power lines and aerospace, there is a notable surge in interest and attention toward the icephobic materials. The increased focus reflects a growing recognition of the crucial role of materials that demonstrate superior resistance to icing phenomenon. However, the intricate correlation between material wettability and icephobicity remains inadequately elucidated. This study aimed to investigate the factors that influence the relationship between icephobicity and different wetting states. The impact of varying surface topographies was examined within the scope of this investigation. A comprehensive analysis was conducted to evaluate the anti-icing and de-icing performances of the surfaces, encompassing anti-frost, ice shear adhesion strength and electro-thermal heating de-icing aspects. Furthermore, the static and dynamic wettability, along with surface free energy measurements, were also performed to enhance the comprehension of icephobicity variation. The detailed water condensation on various surfaces was meticulously observed using environmental scanning electron microscopy (ESEM). The findings elucidated a strong correlation between the icing behaviour and surface topography. It was observed that the surface topography acted as an amplifier, intensifying the deteriorating effect in icephobicity: the formed glaze per unit area exhibited a significant increase with rough asperities; the ice adhesion strength suffered an obvious increase with rough surface and lower hydrophobicity as well as the prolonged ice detachment and overall energy consumption. Therefore, careful consideration should be devoted to the tailoring of surface morphology and wettability when designing and fabricating icephobic surfaces.