Adhesive Technology Research Articles

Методы увеличения магнитоэлектрического эффекта в композитных структурах: обзор

The article provides a review of various methods that can be used to increase the magnetoelectric (ME) effect in composite structures based on magnetostrictive and piezoelectric materials. It is shown that the use of adhesive technology and gradient structure, as well as thermal and thermomagnetic treatment of a magnetostrictive amorphous alloy of an ME structure make it possible to achieve a significant increase in the ME effect. To date, great efforts have been made to optimize the strain amplitude in the piezoelectric and magnetostrictive phases of multilayer ME materials. The use of various technologies in the manufacture of ME composites makes it possible, for example, to increase the sensitivity of magnetic field sensors for biomedical applications. Also, an increase in the ME effect opens up great prospects for further research.

Shear Stress Distribution in Double-lap Adhesive Joints Reinforced with Nylon Fabric: Numerical Investigation

Nowadays there are an increasing number of industrial fields in which adhesive technology finds application. The main reason for their growing interest in both science and production is due to the high structural efficiency of this type of joining. Numerous studies have investigated the stress distribution in the adhesive layer under unreinforced conditions. The present work analyzes the elastic shear stress distribution in double-lap adhesive joints between timber and float glass adherends, both in the classical configuration and with an introduction of a nylon reinforcement in the two-component (2K) structural epoxy adhesives layers. In particular, three geometric configurations were investigated: nylon placed on the inner adherend, outer adherend and both. The result showed how the presence of the nylon inclusion changes the stress distribution in the joint. Numerical modelling of the joints was carried out using FE ANSYS©19 software. The greatest reduction in peak adhesive stresses is achieved by placing the reinforcement at both interfaces of the adherends with the adhesives. In general, it can be observed that the insertion of the reinforcement layer leads to a reduction in peak shear stresses, resulting in a potential increase in the ultimate strength of the joint.

Contemporary Endodontic-Restorative Interface Techniques and Materials

The field of interface techniques and materials is constantly evolving with advancements in technology and research. In the past, the main focus of therapy was eliminating infection and preventing recontamination. The use of magnification and illumination techniques ensures preparation of access cavities, preserving tooth structure while improving visibility for procedures. Adhesive technology plays a role in establishing an endodontic restorative interface. This review highlights the flexibility of etch and self-etch systems, which can be adapted to various clinical scenarios. These systems do not create a bond but also help seal dentin tubules reducing the risk of micro leakage and bacterial ingress. Ultimately, this fortifies the longevity of treatments. The selection of materials is also explored in this review with composite resins gaining prominence due to their properties and versatility. Nano filled composites for restorations exhibit improved mechanical properties that provide durable solutions. To achieve outcomes, it is crucial to incorporate diagnostic tools, adopt conservative access cavity preparation techniques, carefully select appropriate adhesive systems and make strategic material choices. The review highlights the importance of staying vigilant, following up after treatment and taking an approach to overcome challenges in order to provide patient care. Moving ahead, the review suggests that we continue exploring materials and techniques to improve predictability and clinical outcomes at this junction reflecting our continuous commitment to delivering exceptional dental care.

Application of adhesive technology to a new type of glazed panel for curtain walls with an integrated frame

The adhesive technology offers several advantages over traditional joints, allowing the assembly of construction elements with a reduced number of components. The use of large glazed surfaces is a distinctive feature of modern architecture and is reflected in the curtain walls. In traditional applications, glazed panels simply transfer the stress to the substructure (frame), not assuming a structural role. This article reports the results of an experimental campaign on a new type of wooden panels for windows and curtain walls (patent application No. 1020000023128 and European patent 3071775) which provides for the structural collaboration between the frame and glass panels using adhesives. This solution (glazed panels adhesively bonded to the wooden frame) adequately responds to the performance requirements of the highest class of resistance to wind load for windows (C5 – UNI EN 12207), limiting the maximum displacement within 1 mm (maximum deflection of the order of 1/1500).

Resinous deposits in Early Neolithic pottery vessels from the northeast of the Iberian Peninsula

The use of resinous substances, certainly one of the earliest technologies developed by humans, was well-known by Holocene hunter-gatherers at the onset of the Neolithisation process across Europe. Recent research has revealed the use of birch bark tar in the central Mediterranean far from this taxon’s endemic regions both in the Paleolithic and Neolithic periods and shows that the first farmers from the Fertile Crescent hafted lithic tools and waterproofed artefacts using bitumen.The generalised absence of these natural products in south-western Europe may have thus forced a reformulation of Early Neolithic technologies by exploring and benefitting from existing knowledge in local European hunter-gatherer societies. However, information on resin use from the western Mediterranean is still scarce. Here, we report on the analysis of organic residues from 168 pottery sherds by gas chromatography and gas chromatography-mass spectrometry from 10 archaeological sites in this region dating from the second half of the VIth millennium to the first half of the Vth millennium cal BC. In a limited number of samples, minor amounts of several diterpenoids diagnostic of aged Pinaceae resins were detected as mixtures with fats.The presence of pine in the palynological and carpological record supports the human exploitation of this taxon, but its minimal incidence in the anthracological record suggests that other species were selected as fuelwood. This supports the hypothesis that Pinaceae resins were used in association with pottery sporadically but ubiquitously either as its contents, or as post-firing treatments to waterproof the vessels. This demonstrates the development of adhesive technologies and resin-involved labour processes specific to Early Neolithic societies.

Automotive OEMs offered solvent-free and environmentally sustainable threadlocker

As reported earlier this year, Henkel Adhesive Technologies has developed a threadlocker coating for applications in the automotive sector. The company says that it expands its range of automotive preapplied threadlocker coatings and combines high-speed throughput of a flowable product with sustainability advantages of a water-based material. Here we take a closer look at the technology and how it is being used.

Modelling and measuring complexity of traditional and ancient technologies using Petri nets.

Technologies and their production systems are used by archaeologists and anthropologists to study complexity of socio-technical systems. However, there are several issues that hamper agreement about what constitutes complexity and how we can systematically compare the complexity of production systems. In this work, we propose a novel approach to assess the behavioural and structural complexity of production systems using Petri nets. Petri nets are well-known formal models commonly used in, for example, biological and business process modelling, as well as software engineering. The use of Petri nets overcomes several obstacles of current approaches in archaeology and anthropology, such as the incompatibility of the intrinsic sequential logic of the available methods with inherently non-sequential processes, and the inability to explicitly model activities and resources separately. We test the proposed Petri net modelling approach on two traditional production systems of adhesives made by Ju/'hoan makers from Nyae, Namibia from Ammocharis coranica and Ozoroa schinzii plants. We run simulations in which we assess the complexity of these two adhesive production systems in detail and show how Petri net dynamics reveal the structural and behavioural complexity of different production scenarios. We show that concurrency may be prevalent in the production system of adhesive technologies and discuss how changes in location during the process may serve to control the behavioural complexity of a production system. The approach presented in this paper paves the way for future systematic visualization, analysis, and comparison of ancient production systems, accounting for the inherent complex, concurrent, and action/resource-oriented aspects of such processes.

Copper Ions Absorbed on Acrylic-Acid-Grafted Polystyrene Enable Direct Bonding with Tunable Bonding Strength and Debonding on Demand.

Recycling adhesively bonded polymers is inconvenient due to its expensive separation and removal of adhesive residues. To tackle this problem, adhesive technologies are needed allowing debonding on demand and which do not contaminate the surface of the substrate. Direct bonding enabled by oxygen plasma treatment has already achieved substantial adhesion between flat substrates. However, debonding takes place by water, thus limiting the applications of this technology to water-free environments. The work presented in the following shows that this drawback can be overcome by grafting acrylic acid and adding copper(II) ions on the surface of polystyrene. In this process, the number of functional groups on the surface was significantly increased without increasing the surface roughness. The bonding strength between the substrates could be increased, and the process temperature could be lowered. Nevertheless, the samples could be debonded by exposure to EDTA solution under ultrasound. Hence, by combining acrylic acid grafting, variations in the bonding temperatures and the use of copper(II) ions, the bonding strength (5 N to >85 N) and the debonding time under the action of water can be tuned over large ranges (seconds to complete resistance).

Early Phase Enamel Bond Performance of a Two-step Adhesive Containing a Primer Derived from a Universal Adhesive.

To investigate the changes in the enamel bond performance of a two-step adhesive containing a primer derived from a universal adhesive in the early phase before 24 h and compare them to those of other adhesives. The Knoop hardness number (KHN) of the cured adhesive layers and resin composite was measured. A new two-step adhesive using universal adhesive technology, G2-Bond Universal, was tested. Two conventional two-step adhesives, Clearfil SE Bond 2 and OptiBond eXTRa, and an established universal adhesive, Scotchbond Universal Plus Adhesive, were used as comparison materials. Twelve specimens per group were used to measure the shear bond strength (SBS) to bovine enamel in different etching modes. The bonded specimens were stored in distilled water at 37°C for 5 min or 1, 6, 12, or 24 h before SBS testing. The KHN of the adhesive layer and resin composite was determined after the same storage periods as for SBS testing. All adhesives exhibited increased SBS with prolonged storage periods, irrespective of the etching mode. The KHN of the adhesive layer and resin composite increased over time. There were strong positive correlations between the SBS and KHN of the adhesive layer and resin composite. Phosphoric acid pre-etching of enamel effectively increases enamel bond performance. The two-step adhesive G2-Bond Universal demonstrated significantly higher bond strength in the early phase than the other adhesives in self-etch mode.

Fatigue fracture behavior of cured epoxy adhesive containing a surface crack

Adhesive joining technology is important for reducing the weight of an automobile body. As joints can be defective, it is necessary to accurately assess the risk of defects. Dumbbell-shaped bulk specimens were prepared using an epoxy adhesive. A semi-circular artificial crack was introduced in the center of the specimen to conduct the fatigue tests. As a result, it was found that defects smaller than a certain size did not reduce the strength. Using the defect inspection and fatigue test results, a method was proposed to guarantee the strength of the adhesive joints. The test material was extremely sensitive to a crack; however, the linear cumulative damage rule did not hold. Furthermore, the creep life was considerably longer than the fatigue life due to the relaxation effect.

Effects of Flexural Rigidity on Soft Actuators via Adhering to Large Cylinders

This study proposes a soft pneumatic actuator with adhesion (SPAA) consisting of a top fluidic-driven elastic actuator and four bottom adhesive pads for adhering to large cylinders. Finite element models were developed to investigate the bending properties under positive air pressure and the effect of “rib” height on the flexural rigidity of the SPAA. A synchronous testing platform for the adhesive contact state and mechanics was developed, and the bending curvature and flexural rigidity of the SPAA were experimentally measured relative to the pressure and “rib” height, respectively, including the adhesion performance of the SPAA with different rigidities on large cylinders. The obtained results indicate that the SPAA can continuously bend with controllable curvature under positive air pressure and can actively envelop a wide range of cylinders of different curvatures. The increase in the “rib” height from 4 to 8 mm increases the flexural rigidity of the SPAA by approximately 230%, contributing to an average increase of 54% in the adhesion performance of the SPAA adhering to large cylinders. The adhesion performance increases more significantly with an increase in the flexural rigidity at a smaller peeling angle. SPAA has a better adhesion performance on large cylinders than most existing soft adhesive actuators, implying that is more stable and less affected by the curvature of cylinders. To address the low contact ratio of the SPAA during adhesion, the optimization designs of the rigid–flexible coupling hierarchical and differentiated AP structures were proposed to increase the contact ratio to more than 80% in the simulation. In conclusion, this study improved the adhesion performance of soft adhesive actuators on large cylinders and extended the application scope of adhesion technology. SPAA is a basic adhesive unit with a universal structure and large aspect ratio similar to that of the human finger. According to working conditions requirements, SPAAs can be assembled to a multi-finger flexible adhesive gripper with excellent maneuverability.

Research on a New Loading Method for Nano TiO2 Photocatalytic Asphalt Pavement

The main goal of our work was to study a new loading method for photocatalytic asphalt pavement that could effectively solve the problems of photocatalytic degradation efficiency and durability. We adhered nano TiO2 particles to the microscopically textured structure on the surface of glass microbeads by cold alkaline corrosion and high-temperature adhesion technology. We observed good adhesion of nano TiO2 on glass microbeads by a microscopic performance characterization of the composites. The improvement in the light transmittance of the composite material improved the catalytic efficiency of nano TiO2 to a certain extent. Three different groups were established to verify the durability of the nano TiO2 loading method. The result shows that the exhaust gas degradation rate of the spray embedding group did not decrease significantly with the increase in road friction time. Our research provides a new idea for the design of exhaust degradation pavement.

Influence of Silicone Additives on the Properties of Pressure-Sensitive Adhesives.

Research was carried out on the influence of various silicone compounds on the properties of pressure-sensitive adhesives. Silicone-based pressure-sensitive adhesives have good self-adhesive properties and are used in many different industries. However, their thermal resistance is relatively low. In order to improve this property, modifications were made to these adhesives. Compositions were tested, such as viscosity or thermogravimetric analysis, as well as tests of finished products in the form of self-adhesive tapes, i.e., peel adhesion, tack, cohesion at room and elevated temperature, SAFT test (Shear Adhesive Failure Temperature), pot-live (viscosity) and shrinkage. During the tests, an increase in thermal resistance (225 °C), lower shrinkage (0.08%), and lower viscosity was achieved (16.5 Pas), which is a positive phenomenon in the technology of pressure-sensitive adhesives. Thanks to this research, the properties of silicone self-adhesive adhesives have been significantly improved.

Threadlocker combines high throughput with sustainability of water-based materials

Henkel Adhesive Technologies has developed a threadlocker coating for applications in the automotive sector.

The Effect of the Setting Force on the Fatigue Resistance of a Blind Rivet Nut Set in CFRP

Weight reduction is often a key factor in modern mechanical design, therefore materials such as carbon fibre reinforced plastics (CFRP) are increasingly used and integrated within multi-material structures using adhesive technologies, which require high effort and are difficult to disassemble. The capability of a blind rivet nut (BRN) to join different materials without these disadvantages has created a growing industrial interest in the fastener. However, installing a BRN in CFRP laminate induces a significant stress concentration in the plate, which potentially causes damage. Given that ‘damage free’ joints are demanded by the industry, the BRN is often not considered as a suitable joining technique. In the present research, an experimental campaign is performed to investigate the fatigue resistance of a BRN joint in CFRP. It is demonstrated that the resulting compressive stress after installing a BRN can enhance the fatigue resistance of the specimen. The results increase the potential of the BRN as a fastener for CFRP.

A double crosslinking adhesion mechanism for developing tough hydrogel adhesives

Tough hydrogel adhesives that consist of a robust gel network and can strongly adhere to wet tissues have shown great promise as the next generation of bioadhesives. While a variety of chemistries can be utilized to construct the tough gel network, the covalent conjugation methods for tissue adhesion are still limited. Here we report, for the first time, the use of side product-free amine-thiolactone chemistry which initiates a double crosslinking adhesion mechanism to develop tough gel adhesives. Thiolactone groups can conjugate with tissue-surface amines via a ring-opening reaction. The resultant thiol end groups can be further crosslinked into disulfide linkages, enabling the formation of a robust and stable adhesion layer. The thiolactone-bearing tough hydrogel composed of methacrylate-modified gelatin, acrylic acid, and thiolacone acrylamide exhibited good biocompatibility and mechanical properties, and strong adhesion to various types of engineering solids and tissues. We also demonstrated its ability to function as a tissue sealant and drug depot. The novel adhesion mechanism will diversify future design of bioadhesives for hemostasis, drug delivery, tissue repair, and other applications. Statement of significanceTough hydrogel adhesives with excellent tissue-adhesive and mechanical properties have demonstrated tremendous promise for hemostasis, tissue repair, and drug delivery applications. However, the covalent chemistry for tissue adhesion has been limited, which narrows the choice of materials for the design of bioadhesives and may pose a safety concern. Here, for the first time, we report the use of side product-free amine-thiolactone chemistry, which involves a double crosslinking adhesion mechanism, for developing tough hydrogel adhesives. We demonstrate that thiolactone-bearing tough hydrogels exhibit favorable biocompatibility and mechanical properties, and superior adhesion to both engineering solids and tissues. Our new adhesion technology will greatly facilitate future development of advanced bioadhesives for numerous biomedical applications.

The state-of-the-art of adhesion and locomotion technologies for exploring small celestial bodies

This paper attempts to present a comprehensive review of adhesion and locomotion technology for exploring small celestial bodies (SCBs). The long-term landing, adhesion, and locomotion of space robots on the surface of SCBs can maximize the scientific value of exploration missions. They can also provide technical reserves and support for future SCBs resource exploitation and crewed missions. Based on this background, the current progress and planning of SCBs exploration missions are first reviewed. Due to the special microgravity environment and complex surface characteristics of SCBs, adhesion and locomotion on SCBs surfaces are extremely difficult. The surface environmental characteristics of SCBs and their influences and limitations on the adhesion and locomotion of space robots are analyzed. The progress of classic adhesion and locomotion technology on SCBs is classified and studied, including anchoring adhesion, instantaneous adhesion, and locomotion technologies. Based on the research of climbing and soft robots, various bionic adhesion and locomotion techniques are introduced, with emphasis on their application prospects in SCBs exploration missions. Finally, according to the trend of future SCBs exploration missions, the critical issues and research direction of related technologies are presented, and concluding remarks are provided.

Caterpillar-Inspired Insect-Scale Climbing Robot Using Dry Adhesives

Surface-to-surface transitions, vertical and inverted locomotion, and high payload capacity are important requirements for a climbing robot. Despite many previous approaches, the miniaturization of climbing robots that satisfy these requirements is still a big challenge. In this letter, we present an insect-scale wheeled climbing robot that employs a low-cost dry adhesive technology. The design, inspired by caterpillars, consists of 2 main links that are connected by a pivot joint. The prototype robot measures a length of 40 mm and a width of 10 mm, and it weighs 1.7 g. On a horizontal surface, the robot moves with a speed of 12.3 mm/s and can drag a load weight of 10 g (six times its weight) at a speed of 4 mm/s. The high torque-to-weight ratio achieved by two micro-geared ultrasonic motors permits vertical and inverted locomotion while carrying a high payload capacity (120% of the robot’s weight). The locomotion strategy for surface-to-surface transitions, i.e., movements at right angle corners, is substantiated by the functionality of the pivot joint. To satisfy the design requirements, many dry adhesive tapes are evaluated, and the climbing robot with an appropriate adhesion force is demonstrated.

Development of bus body technologies in terms of corrosion and durability

The object of this study is the technology of bus bodies and the formation of recommendations for design bodywork subject to the regulated durability of the body introduced into production. Advancing the technology of manufacturing bus bodies implies improving anti-corrosion protection, using new polymeric materials, and reducing the length of welds. The issue of corrosion resistance of bus bodies has been considered. It is established that the use of new polymeric materials will increase the corrosion resistance of bus bodies while existing technologies weakly protect against corrosion (resource up to 5 years). The peculiarity of this study is that the adhesion of new materials has been tested, with artificial aging, which confirms the durability of glued joints. According to the old technology, the body was exposed to anticorrosive treatment after welding the cladding with uncovered places left between the frame and body cladding, which provoked corrosion. The main idea is that in the new technology, the cladding is welded or glued after the body frame is fully coated with primer. New technologies and materials not used in the automotive industry have been proposed. Three variants of technologies were put into production. First: the welding of steel zinc sheets. In welding sites, the frame is covered with conductive primer. It was implemented for school buses (after 7 years, without damage). Second: gluing steel zinc sheets. It was implemented for city buses (after 6 years, without damage). Third: gluing sheets from composite materials not used in the automotive industry. The transition to new adhesive cladding technologies from composite corrosion-resistant materials instead of steel sheet, reduces by 2.5–3 times the length of welds (up to 20 years without damage). The studies have confirmed the strength of glued joints (cohesion rupture exceeds 95 %). The reliability of glued joints and high corrosion resistance of the body have been confirmed in the operation of buses. The scope of practical use of the results: bus-building plants. The reported results are suitable for production of all types while cataphoretic coatings are only for mass production

Henkel technology aids expansion of EV infrastructure and helps to protect medical devices

Two diverse – but equally important – applications of sealing technology developed by Henkel Adhesive Technologies form the subject of this focus article. The first involves the important role select protection and thermal control materials are playing in the expansion of infrastructure dedicated to servicing electric vehicles (EVs), whilst in the second, low-pressure moulding materials are being used to protect and seal medical electronics. In both cases, ruggedness, safety and reliability are essential.