Tensile Adhesion Strength Research Articles

Antimicrobial adhesive films by plasma-enabled polymerisation of m-cresol

This work reveals a versatile new method to produce films with antimicrobial properties that can also bond materials together with robust tensile adhesive strength. Specifically, we demonstrate the formation of coatings by using a dielectric barrier discharge (DBD) plasma to convert a liquid small-molecule precursor, m-cresol, to a solid film via plasma-assisted on-surface polymerisation. The films are quite appealing from a sustainability perspective: they are produced using a low-energy process and from a molecule produced in abundance as a by-product of coal tar processing. This process consumes only 1.5 Wh of electricity to create a 1 cm2 film, which is much lower than other methods commonly used for film deposition, such as chemical vapour deposition (CVD). Plasma treatments were performed in plain air without the need for any carrier or precursor gas, with a variety of exposure durations. By varying the plasma parameters, it is possible to modify both the adhesive property of the film, which is at a maximum at a 1 min plasma exposure, and the antimicrobial property of the film against Escherichia coli, which is at a maximum at a 30 s exposure.

Structural Heteropolysaccharide Adhesion to the Corneal Glycocalyx

The cornea presents unique challenges to wound care. The cornea is constantly exposed to bacterial colonization, has ongoing risk of wound‐related astigmatism, and is cumbersome for traditional wound dressings. A potential solution to these challenges is provided by the corneal glycocalyx.Recent high pressure rapid freezing fixation techniques suggest that the glycocalyx is much thicker than previously believed. In the case of the cornea, the glycocalyx may provide an opportunity for wound care anchored to the transmembrane carbohydrate surface layer.To probe the surface glycocalyx we used a plant‐derived structural heteropolysaccharide called pectin. Pectin has been shown to mirror the structure of the glycocalyceal surface layer of visceral organs. To test the adhesivity of pectin to the corneal glycocalyx, high methoxyl citrus pectin was molded into tape form. Bovine globes were obtained from a local abattoir and used same day. Experiments were performed with custom fixtures using a materials analyzer (TA‐XT plus, Stable Micro Systems). To assess pectin adhesion to cornea, pectin was compressed onto the corneal surface then withdrawn, recording force and distance. A corneal incision was sealed with pectin and subject to increased pressure, until leak. At least three biologic replicates were analyzed, expressed as mean ± one standard deviation. Significance was assessed by Student’s T‐test. Pectin films on cornea were also fixed with formalin and imaged using a scanning electron microscope (Philips XL30 ESEM).Pectin films were flexible, translucent, thin (80um), and did not distort an Amsler grid. Pectin was significantly more adherent (3.2±0.54 N) to the bovine cornea than control polymers nanocellulose fibers (1.2±0.4 N), sodium hyaluronate (1.7±0.7 N), and carboxymethyl cellulose (1.3±0.1)(p<0.05). The work of adhesion, reflecting the area under the adhesion curve, was also significantly greater (p<0.05, asterisk, Figure 1). The cornea incisions sealed with pectin were resistant to pressure fluctuations ranging from ‐51.3±8.9 mmHg to +214.4±68.0 mmHg, both extremes beyond physiologic human intraocular pressures. Sudden or complete sealant failure was not observed. Consistent with these findings, scanning electron microscopy demonstrated a low‐profile tape densely adherent to the bovine cornea (Figure 2).The tensile and peel adhesive strength of the pectin biopolymer suggests a mechanism of polymer‐polymer entanglement with the corneal glycocalyx. As a therapeutic option for corneal wounds, the entangled pectin provides not only a protective barrier, but also an opportunity for pectin‐embedded drug delivery.

Oxide Free Wire Arc Sprayed Coatings—An Avenue to Enhanced Adhesive Tensile Strength

Conventionally, thermal spraying processes are almost exclusively carried out in an air atmosphere. This results in oxidation of the particles upon thermal spraying, and thus, the interfaces of the splats within the coating are oxidized as well. Hence, a full material bond strength cannot be established. To overcome this issue, a mixture of monosilane and nitrogen was employed in the present study as the atomising and environment gas. With this approach, an oxygen partial pressure corresponding to an extreme-high vacuum was established in the environment and oxide-free coatings could be realized. It is shown that the oxide-free particles have an improved substrate wetting behaviour, which drastically increases the adhesive tensile strength of the wire arc sprayed copper coatings. Moreover, the altered deposition conditions also led to a significant reduction of the coating porosity.

Enhanced mechanical performances of epoxy asphalt adhesives modified by graphene oxide

The graphene oxide (GO) was used to improve the mechanical performances of epoxy asphalt (EA) by preparing GO/EA composite. The influence of the GO dosage on the micro-structure, curing rheology, mechanical and thermal properties of GO/EA was investigated. According to the XRD and Fourier transform infrared spectra, the GO was exfoliated in the EA matrix and modified EA by non-covalent strategy. GO decreased the rotational viscosity of EA and increased the pot life. The GO/EA with 0.1 wt.% GO showed excellent toughness that the elongation at break was increased by 164%, and the tensile and pull-off adhesion strength were nearly equal to that of EA. The addition of GO improved the original thermal decomposition temperature (T 5%), glass transition temperature (T g), compatibility and stiffness of the EA. The improved mechanical and thermal properties of GO/EA may be attributed to (1) excellent performances of GO and (2) inhibiting effect of GO on the EA curing process.

Amelotin Promotes Mineralization and Adhesion in Collagen-Based Systems.

Periodontitis is characterized by the destruction of tooth-supporting tissues including the alveolar bone. Barrier membranes are used in dentistry for tissue regenerative therapy. Nevertheless, conventional membranes have issues related to membrane stability and direct induction of bone mineralization. Amelotin (AMTN), an enamel matrix protein, regulates hydroxyapatite crystal nucleation and growth. To apply an AMTN membrane in clinical practice, we investigated the mineralizing and adhesive effects of recombinant human (rh) AMTN in vitro using a collagen-based system. Collagen hydrogel incorporated with rhAMTN (AMTN gel) and rhAMTN-coated dentin slices were prepared. AMTN gel was then applied on a commercial membrane (AMTN membrane). Samples were incubated for up to 24 h in mineralization buffer, and the structures were observed. The peak adhesive tensile strength between the dentin and AMTN membrane was measured. Using an enzyme-linked immunosorbent assay, the release kinetics of rhAMTN from the membrane were investigated. The AMTN gel resulted in the formation of hydroxyapatite deposits both onto and within the collagen matrix. Furthermore, coating the dentin surface with rhAMTN promoted the precipitation of mineral deposits on the surface. Interestingly, site-specific mineralization was observed in the AMTN membrane. Only 1% of rhAMTN was released from the membrane. Hence, the AMTN membrane adhered to the dentin surface with more than twofold greater tensile strength than that detected for a rhAMTN-free barrier membrane. RhAMTN can accelerate mineralization and adhesion in collagen-based systems. Furthermore, the AMTN membrane could inform the optimal design of calcified tissue regenerative materials. The online version contains supplementary material available at 10.1007/s12195-022-00722-2.

Assembly of Graphene Platelets for Bioinspired, Stimuli-Responsive, Low Ice Adhesion Surfaces.

Design and fabrication of functional materials for anti-icing and deicing attract great attention from both the academic research and industry. Among them, the study of fish-scale-like materials has proved that enabling sequential rupture is an effective approach for weakening the intrinsic interface adhesion. Here, graphene platelets were utilized to construct fish-scale-like surfaces for easy ice detachment. Using a biomimicking arrangement of the graphene platelets, the surfaces were able to alter their structural morphology for the sequential rupture in response to external forces. With different packing densities of graphene platelets, all the surfaces showed universally at least 50% reduction in atomistic tensile ice adhesion strength. Because of the effect of sequential rupture, stronger ice–surface interactions did not lead to an obvious increase in ice adhesion. Interestingly, the high packing density of graphene platelets resulted in stable and reversible surface morphology in cyclic tensile and shearing tests, and subsequently high reproducibility of the sequential rupture mode. The fish-scale-like surfaces built and tested, together with the nanoscale deicing results, provided a close view of ice adhesion mechanics, which can promote future bioinspired, stress-responsive, anti-icing surface designs.

Relationship between the Physicochemical and Electrostatic Charge Characteristics of Filler Materials on the Morphological and Adhesive Pull-Off Tensile Strength of Asphalt Mastics

Relationship between the Physicochemical and Electrostatic Charge Characteristics of Filler Materials on the Morphological and Adhesive Pull-Off Tensile Strength of Asphalt Mastics

Influence of Surface Roughness of Aluminum Alloy Substrate on Tensile Adhesive Strength of Plasma-Sprayed Yttria-Stabilized Zirconia Coatings

Influence of Surface Roughness of Aluminum Alloy Substrate on Tensile Adhesive Strength of Plasma-Sprayed Yttria-Stabilized Zirconia Coatings

Study of mechanical, acoustic, and microstructure properties of lightweight mortars produced with expanded clay

The inclusion of alternative materials in concrete production is very efficient, having a sustainable bias and improving the main properties of concrete. Expanded clay has been used to produce mortar and concrete, partially replacing the aggregate with the main purpose of reduces specific mass and the weight of the structure, also improves acoustic and thermal characteristics. This study proposes the use of expanded clay to a lightweight laying and coating mortar compared to conventional mortars. It was investigated the influence of expanded clay as a substitute for conventional fine aggregate in mortars in ratios of (5, 10, 15, and 20) %. Tests were carried out in the fresh (consistency index, mass density, incorporated air, and water retention) and hardened states (flexion tensile strength, axial compression, apparent mass density, and potential tensile adhesion strength) based on the Brazilian Technical Standards Association (ABNT). The microstructure was also investigated using a scanning electron microscope (SEM). The results show that the replacements improved the strength of the mortars, being 20% higher than expected by the standard. Expanded clay is a sustainable alternative and adds new properties (thermal and acoustic) to mortars.

Interlaboratory Comparison as a Source of Information for the Product Evaluation Process. Case Study of Ceramic Tiles Adhesives.

In this study, the results obtained by 19 laboratories participating in 2 editions of the interlaboratory comparison (ILC) determining 2 properties of ceramic tiles adhesives (CTAs), i.e., initial tensile adhesion strength and tensile adhesion strength after water immersion following EN 12004, were analyzed. The results show that participating laboratories maintain a constant quality of their work. The use of z-score analysis, under ISO 13528, allows for classifying 89.5% to 100% of laboratories as satisfactory, depending on the measurement’s kind and edition. The remaining laboratories are classified as questionable. The investigation of the predominant mode of failure of the CTA’s samples tested in the two editions shows significant differences. From the perspective of laboratories, the goal of the ILC has been achieved. From the standpoint of a manufacturer who evaluates a product’s properties when placing it on the market, the results indicate the necessity of a particular treatment of the product evaluation process because the variability of the obtained results is significant. It increases the possibility of the product failing to meet the assessment criteria verified by the construction market supervision authorities. The manufacturer must consider all possible variations in the risk analysis, including the ILC results, to improve the assessment process of CTAs.

3D Printed Buccal Films for Prolonged-Release of Propranolol Hydrochloride: Development, Characterization and Bioavailability Prediction

Gelatin-polyvinylpyrrolidone (PVP) and gelatin-poly(vinyl alcohol) (PVA) mucoadhesive buccal films loaded with propranolol hydrochloride (PRH) were prepared by semi-solid extrusion 3D printing. The aim of this study was to evaluate the effects of the synthetic polymers PVP and PVA on thermal and mechanical properties and drug release profiles of gelatin-based films. The Fourier-transform infrared spectroscopy showed that hydrogen bonding between gelatin and PVP formed during printing. In the other blend, neither the esterification of PVA nor gelatin occurred. Differential scanning calorimetry revealed the presence of partial helical structures. In line with these results, the mechanical properties and drug release profiles were different for each blend. Formulation with gelatin-PVP and PRH showed higher tensile strength, hardness, and adhesive strength but slower drug release than formulation with gelatin-PVA and PRH. The in silico population simulations indicated increased drug bioavailability and decreased inter-individual variations in the resulting pharmacokinetic profiles compared to immediate-release tablets. Moreover, the simulation results suggested that reduced PRH daily dosing can be achieved with prolonged-release buccal films, which improves patient compliance.

Prediction of the bond strength of FRP-to-concrete under direct tension by ACO-based ANFIS approach

In this study, a hybrid model integrating the ant colony optimization (ACO) algorithm and fuzzy c-means (FCM) clustering method into the adaptive neuro-fuzzy inference system (ANFIS) was proposed to predict the bond strength between fibre-reinforced polymer (FRP) sheets and concrete surface under direct tension. Eight parameters including the compressive strength of concrete, maximum aggregate size, tensile strength of FRP, thickness of FRP, elastic modulus of FRP, adhesive tensile strength, length of FRP and width of FRP are employed as the inputs, and the bond strength is used as the output variable. A comparison was conducted between some existing empirical models and the proposed hybrid ACO-based ANFIS model. The results confirmed that the developed ACO-based ANFIS model exhibits greater accuracy than the other eleven models, with higher coefficient of determination (R2 = 0.97) and Nash-Sutcliffe efficiency index (NS = 0.97), and lower root mean squared error (RMSE = 1.29 kN), mean absolute error (MAE = 0.81 kN) and mean absolute relative error (MARE = 0.053), while according to the Akaike information criterion (AIC) index, the accuracy of this model lies in its considerable complexity compared to others.

Mussel-Inspired Epoxy Bioadhesive with Enhanced Interfacial Interactions for Wound Repair

The balance between high mechanical properties and strong adhesion strength is crucial in designing and preparing a bio-based hydrogel adhesive for wound closure. Although the adhesion performance of bioadhesives has been remarkably improved by modification with catechol groups, their mechanical properties are yet to meet the biomedical requirements. In this study, mussel-inspired epoxy bioadhesives (CSD-PEG) were synthesized based on catechol-modified chitosan oligosaccharide (CSD) and polyethylene glycol diglycidyl ether (PEGDGE) through nucleophilic substitution. Notably, the CSD-PEG adhesive showed high mechanical and adhesion strengths, which were up to 50.7 kPa and 136.7 kPa, respectively. It was confirmed that a certain amount of the epoxy and catechol groups provided multiple interfacial interactions among the adhesives, substrates, and polymer chains for enhancing the performance of adhesives. The adhesives showed good binding and repairing effects for wound closure and favorable biocompatibility in vivo. The prepared CSD-PEG adhesives are expected to be a promising candidate for surgical tissue repair, wound closure, and tissue engineering fields. Statement of significanceCurrent reported adhesives composed of biopolymers generally suffer from poor mechanical properties or weak tissue adhesiveness. Therefore, to achieve simultaneously high mechanical and adhesion properties in a bio-based adhesive for wound closure is a big challenge. In this study, mussel-inspired adhesive hydrogels (CSD-PEG) were prepared based on catechol-modified chitosan oligosaccharide (CSD) and polyethylene glycol diglycidyl ether (PEGDGE). The tensile strength and adhesive strength of CSD-PEG on porcine skin reached 50.7 kPa and 136.7 kPa, respectively, which were higher than those for most reported biopolymeric adhesives, mainly due to the multiple interfacial interactions between the catechol and epoxy groups. The CSD-PEG bioadhesives also showed good binding and repairing effects for wound closure and tissue regeneration in vivo.

A new nanoparticle-reinforced silicone rubber composite integrating high strength and strong adhesion

A bulk modification method is developed in this paper to achieve a new nanoparticle-reinforced silicone rubber composite with high strength and strong adhesion. Different from existing modification methods, an adhesion promoter is added in order to improve the adhesive property in addition to the surface modified silica nanoparticle. Furthermore, the adhesion promoter also exhibits an excellent compatibility with the silicone rubber. The tensile strength and shear adhesive strength of the new composite can reach up to 10.4 MPa and 90 kPa, respectively, both of which are much higher than their counterparts in the popular silicone rubber product Sylgard184. Moreover, the strong adhesion performance of the composite exhibits a good stability in either several-hour use or many attachment/detachment cycles. The present composite shows apparent advantages over existing silicone rubber products in not only the direct use as an adhesive material, but also potential applications for manufacturing advanced adhesive devices such as wearable electronics.

Development of a novel direct dental pulp-capping material using 4-META/MMA-TBB resin with nano hydroxyapatite

In the case of dental pulp exposure, direct pulp capping is often performed to preserve vital dental pulp tissue. Numerous studies regarding the development of direct pulp-capping materials have been conducted, but materials with an appropriate sealing ability, which induce dense reparative dentin formation, have not been developed. Although nano hydroxyapatite (naHAp) is a bone-filling material with bioactivity and biocompatibility, the inductive effects of naHAp on reparative dentin formation remain unclear. In the present study, the effects of dental adhesive material 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate tri-n-butylborane [4-META/MMA-TBB or Super-bond (SB)], which included 10%, 30%, and 50% naHAp (naHAp/SB) on odontoblastic differentiation of dental pulp stem cells (DPSCs) and reparative dentin formation were investigated. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer analysis were performed to verify the existence of naHAp particles on the surface of naHAp/SB discs. The tensile adhesive strength of naHAp/SB was measured using a universal testing machine. As a result, 10% naHAp/SB and 30% naHAp/SB showed almost the same tensile adhesive strength as SB but 50% naHAp/SB showed significantly lower than the other experimental group. WST-1 proliferation assay and SEM analysis revealed that naHAp/SB did not affect the proliferation of DPSCs. Calcium release assay, quantitative RT-PCR, and western blotting analysis demonstrated that naHAp/SB did not release calcium ion but 30% naHAp/SB increased the expression of calcium-sensing receptor (CaSR) in DPSCs. Additionally, quantitative RT-PCR, western blotting analysis, Alizarin Red S- and von Kossa staining revealed that 30% naHAp/SB induced odontoblastic differentiation of DPSCs, which was inhibited by a MEK/ERK inhibitor and CaSR antagonist. Furthermore, 30% naHAp/SB promoted dense reparative dentin formation in an experimentally-formed rat dental pulp exposure model. These findings suggest that 30% naHAp/SB can be used as an ideal direct pulp capping material.

Functional Adhesion of Pectin Biopolymers to the Lung Visceral Pleura.

Pleural injuries and the associated “air leak” are the most common complications after pulmonary surgery. Air leaks are the primary reason for prolonged chest tube use and increased hospital length of stay. Pectin, a plant-derived heteropolysaccharide, has been shown to be an air-tight sealant of pulmonary air leaks. Here, we investigate the morphologic and mechanical properties of pectin adhesion to the visceral pleural surface of the lung. After the application of high-methoxyl citrus pectin films to the murine lung, we used scanning electron microscopy to demonstrate intimate binding to the lung surface. To quantitatively assess pectin adhesion to the pleural surface, we used a custom adhesion test with force, distance, and time recordings. These assays demonstrated that pectin–glycocalyceal tensile adhesive strength was greater than nanocellulose fiber films or pressure-sensitive adhesives (p < 0.001). Simultaneous videomicroscopy recordings demonstrated that pectin–glycocalyceal adhesion was also stronger than the submesothelial connective tissue as avulsed surface remnants were visualized on the separated pectin films. Finally, pleural abrasion and hyaluronidase enzyme digestion confirmed that pectin binding was dependent on the pleural glycocalyx (p < 0.001). The results indicate that high methoxyl citrus pectin is a promising sealant for the treatment of pleural lung injuries.

Reuse of Sintered Sludge from Municipal Sewage Treatment Plants for the Production of Lightweight Aggregate Building Mortar

In recent years, the sludge produced by municipal sewage treatment plants has become an important recyclable resource for producing green building materials. After the systematic processing of incineration and particle formation, the sintered sludge can be processed into fine lightweight aggregate to produce building mortar with the controlled leaching of heavy metals and radioactivity. In this paper, to increase its economic and environmental benefits, mortar with sintered sludge aggregate was made by cement admixing of fly ash or limestone powder. The water-to-binder ratio was set at three levels—0.82, 0.68, and 0.62—and either flay ash or limestone powder was used to replace equal masses of cement at 10%, 20%, or 30%. Eighteen groups of mortar were studied to evaluate their workability, air content, compressive strength, tensile adhesive strength, dry density, and thermal conductivity. The results indicate that with a proper water-to-binder ratio, and the replacement ratio of fly ash or limestone powder, the mortar can be produced with good workability, consistency, water-retention rate, layering degree, and setting time. The mortar made with sintered sludge lightweight aggregate, designated by the mix-proportion method for conventional lightweight aggregate mortar, did not meet the target strength, although the compressive strength of mortar was no less than 3.0 MPa, which meets the strength grade M2.5. The tensile adhesive strength reached 0.18 MPa. The mortar was super lightweight with a dry density less than 400 kg/m3, and a thermal conductivity within 0.30~0.32 W/(m⋅K). The effects of water-to-binder ratio and replacement ratio of fly ash or limestone powder on the above properties are discussed with test results. The study provides a basis for using sintered sludge lightweight aggregate for building mortar.

Biomaterial-Assisted Anastomotic Healing: Serosal Adhesion of Pectin Films.

Anastomotic leakage is a frequent complication of intestinal surgery and a major source of surgical morbidity. The timing of anastomotic failures suggests that leaks are the result of inadequate mechanical support during the vulnerable phase of wound healing. To identify a biomaterial with physical and mechanical properties appropriate for assisted anastomotic healing, we studied the adhesive properties of the plant-derived structural heteropolysaccharide called pectin. Specifically, we examined high methoxyl citrus pectin films at water contents between 17–24% for their adhesivity to ex vivo porcine small bowel serosa. In assays of tensile adhesion strength, pectin demonstrated significantly greater adhesivity to the serosa than either nanocellulose fiber (NCF) films or pressure sensitive adhesives (PSA) (p < 0.001). Similarly, in assays of shear resistance, pectin demonstrated significantly greater adhesivity to the serosa than either NCF films or PSA (p < 0.001). Finally, the pectin films were capable of effectively sealing linear enterotomies in a bowel simulacrum as well as an ex vivo bowel segment. We conclude that pectin is a biomaterial with physical and adhesive properties capable of facilitating anastomotic healing after intestinal surgery.

Application potentials and limits of rock reinforcement with polymer-based adhesives

Gravitational mass movements, such as rockfalls or landslides, represent geo-risks that require geotechnical safety measures in order to avert monetary damage and to protect human life. For the targeted stabilization and consolidation of rock masses, the gluing of rock which is known from mining and tunnel construction, is ideal. Here, an adhesive is grouted into the rock fissures which, when cured, hold the rock together by means of adhesive and cohesive forces. The selection of the right adhesive is of great importance, as it has a decisive influence on the mechanical properties of the rock and thus determines the success of the securing measure. Various adhesives such as resins and acrylate gel were examined in an extensive experimental laboratory program which was expanded to include numerical simulations with FLAC3D. The subject of the laboratory tests are jointed sandstone samples. The test program of the rock mechanical standard tests was supplemented by special tests, such as adhesive tensile strength tests to determine the adhesion between adhesive and sandstone. In order to assess the effectiveness of the adhesive bond, glued and intact sandstone samples were compared. Based on the experimental and numerical investigations, the application possibilities and limits of different polymer-based adhesives are shown and an application recommendation is given.

Adhesion Studies during Generative Hybridization of Textile-Reinforced Thermoplastic Composites via Additive Manufacturing.

Generative hybridization enables the efficient production of lightweight structures by combining classic manufacturing processes with additive manufacturing technologies. This type of functionalization process allows components with high geometric complexity and high mechanical properties to be produced efficiently in small series without the need for additional molds. In this study, hybrid specimens were generated by additively depositing PA6 (polyamide 6) via fused layer modeling (FLM) onto continuous woven fiber GF/PA6 (glass fiber/polyamide 6) flat preforms. Specifically, the effects of surface pre-treatment and process-induced surface interactions were investigated using optical microscopy for contact angle measurements as well as laser profilometry and thermal analytics. The bonding characteristic at the interface was evaluated via quasi-static tensile pull-off tests. Results indicate that both the bond strength and corresponding failure type vary with pre-treatment settings and process parameters during generative hybridization. It is shown that both the base substrate temperature and the FLM nozzle distance have a significant influence on the adhesive tensile strength. In particular, it can be seen that surface activation by plasma can significantly improve the specific adhesion in generative hybridization.