摘要 :
The properties of a VK-51 high-strength epoxy film adhesive containing different reinforcing fabric fillers are given. The effect of reinforcing fillers—fabrics based on a mixture of lavsan and viscose fibers (90 : 10%) and BNK-4...
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The properties of a VK-51 high-strength epoxy film adhesive containing different reinforcing fabric fillers are given. The effect of reinforcing fillers—fabrics based on a mixture of lavsan and viscose fibers (90 : 10%) and BNK-40 latex or based on 100% lavsan fiber (VK-51A adhesive), a T-10-80 fiberglass (VK-51 AS adhesive), and an A3(S)-type fiberglass mesh (VK-51MA adhesive)—on the properties of the adhesive and adhesive joints on its basis is shown.
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We demonstrate that the inclusion of subsurface microfluidic features in a soft polymer surface, whose internal pressure can be varied, may be used to modify the effective radius of curvature of the contact and thus switch the mag...
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We demonstrate that the inclusion of subsurface microfluidic features in a soft polymer surface, whose internal pressure can be varied, may be used to modify the effective radius of curvature of the contact and thus switch the magnitude of the adhesion of the surface to a harder counterface from one state to another - in other words to control the 'stickiness' of the surface. In these circumstances, adhesion depends on van der Waal forces and can be described by the classic treatment of Johnson, Kendall and Roberts. The pressurization of the subsurface chambers results in the rapid emergence of surface features with reduced radii of curvature which drastically decreases the area available for contact so providing a reduction of up to 90% in the adhesion force of a surface from its original 'sticky' state. It is demonstrated that this mechanism can provide a quick, reversible and clean detachment.
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Micropillar adhesives have gained increasing attention because they generate high pull-off forces. The generation of high friction, however, has been proven difficult with such geometries, because micropillars tend to buckle under...
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Micropillar adhesives have gained increasing attention because they generate high pull-off forces. The generation of high friction, however, has been proven difficult with such geometries, because micropillars tend to buckle under shear loading. Here, we fabricated orthogonal arrays of composite poly-dimethoxysiloxane (PDMS) micropillars with a stiff core and spin-coated them with PDMS solutions to form a soft coating, as well as bridges between neighboring micropillars. We used 10 wt% and 5 wt% PDMS solution to obtain thick or thin bridges, respectively. The micropillars had an average height of about 60 μm and a diameter of 40 μm. Adhesion and friction measurements were performed with three types of adhesives (i.e., without bridges and with either thin or thick bridges) as well as unpatterned samples as reference, on stiff glass substrates and on deformable PDMS substrates. We found that, on PDMS substrates, bridging resulted in increased friction, compared to non-bridged micropillars. Friction increased with increasing bridge thickness, presumably due to buckling prevention. The adhesives were also subjected to 99 repeating friction cycles to test the effect of micropillar bridging on the durability of the adhesives. The results showed that adhesives with thick micropillar bridges preserved their friction performance over the cycles, whereas adhesives with no bridges or thin bridges exhibited a gradual decay of friction.
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The adhesion property between asphalt binder and aggregate significantly influences structural stability, service performance, and damage evolution of the asphalt mixture. However, the understanding of adhesion property is still i...
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The adhesion property between asphalt binder and aggregate significantly influences structural stability, service performance, and damage evolution of the asphalt mixture. However, the understanding of adhesion property is still immature. Some research gaps still exist and need to be investigated further, including the adhesion mechanism cannot explain the moisture damage phenomenon well, the adhesion characterizations under different scales are weakly associated, and the key factors that play the dominant role in the adhesion property are not clear enough. In this paper, in order to have a comprehensive understand about adhesion property between asphalt binder and aggregate, the common and recent researches about mechanism, evaluation methods and indexes, influence factors, improvements of adhesion property between asphalt binder and aggregate has been reviewed. In addition, further recommendations are also suggested for a better understanding the adhesion property to improve the service life of roads. (C) 2020 Elsevier Ltd. All rights reserved.
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The rapid growth in the miniaturized mechanical and electronic devices
industry has created the need for temporary attachment systems that can
carry out pick-and-place and transfer printing tasks for fragile and tiny parts.
Cur...
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The rapid growth in the miniaturized mechanical and electronic devices
industry has created the need for temporary attachment systems that can
carry out pick-and-place and transfer printing tasks for fragile and tiny parts.
Current systems are limited by a fundamental trade-off between adhesive
strength and state-changing trigger force, which causes the need for a rapidly
switchable adhesive. In this study, an elastomeric microstructure is presented
combining a trapezoidal-prism-shaped (TPS) and a mushroom-shaped
microstructure, which overcomes the trade-off with the help of the TPS
structure. The optimal design exhibits a strong adhesive strength of 87.8 kPa
and a negligible detachment strength of <0.07 kPa with a low trigger shear
stress of 10.7 kPa on smooth glass surfaces. The large tip-to-stem ratio (50 to
20 μm) enhances the suction effect, allowing the microstructure to maintain
its adhesive performance even in wet conditions. Pick-and-place manipulation
tasks of a single and an array of ultralight parts from micrometer to millimeter
scales are performed to demonstrate the capability of handling fragile and tiny
parts. Moreover, it demonstrates the ability to transfer parts across water and
air interfaces. This proposed microstructure offers a facile solution for
manipulating microscale fragile parts in dry and wet conditions.
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摘要 :
Octopus suckers offer remarkable adhesion performance against nonporous surfaces and have inspired extensive research to develop artificial adhesives. However, most of existing octopus-inspired adhesives are either passive without...
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Octopus suckers offer remarkable adhesion performance against nonporous surfaces and have inspired extensive research to develop artificial adhesives. However, most of existing octopus-inspired adhesives are either passive without an actuation strategy or active but not energy efficient. Here, a novel design of a magnetically actuated, energy-efficient smart adhesive with rapidly tunable, great switchable, and highly reversible adhesion strength inspired by the elastic energy storage mechanism in octopus suckers is reported. The smart adhesive features two cavities separated by an elastic membrane with the upper cavity filled with magnetic particles while the lower one empty. The deformation of the elastic membrane can be actively controlled by an external magnetic field to change the cavity volume, thus generating a cavity-pressure-induced adhesion. Systematically experimental and theoretical studies reveal the fundamental aspects of design and operation of the smart adhesive and give insights into the underlying adhesion mechanisms. Demonstrations of this smart adhesive in transfer printing and manipulation of various surfaces in both dry and wet environments illustrate the potential for deterministic assembly and industrial or robotic manipulation.
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The paper describes new developments by the All-Russian Scientific Research Institute of Avia- tion Materials in the field of mechanical rubber adhesives and technologies for their use in aeronautical engi- neering. The basic prop...
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The paper describes new developments by the All-Russian Scientific Research Institute of Avia- tion Materials in the field of mechanical rubber adhesives and technologies for their use in aeronautical engi- neering. The basic properties of cold-setting rubber adhesives and adhesives designed for bonding rubbers with metals in the process of vulcanization are given. The advantages of the new adhesives relative to existing adhesives or those used previously are shown.
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The paper presents selected aspects of the effect of primers on adhesive properties and strength of aluminium sheet adhesive joints, made using polyurethane adhesives. The strength of adhesive joints was determined based on two cu...
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The paper presents selected aspects of the effect of primers on adhesive properties and strength of aluminium sheet adhesive joints, made using polyurethane adhesives. The strength of adhesive joints was determined based on two cure time variants: 15 and 64h. It was found that the longer cure time at a humidity of 33% is more desired, as it leads to a substantial increase in strength of the tested adhesive joints. In addition, two variants of surface preparation were applied: degreasing and degreasing followed by the application of a primer (a pro-adhesive agent). It was observed that the primer application prior to the application of an adhesive leads to a significant increase in strength compared to the variant where the adhesive application is preceded only by degreasing. Moreover, the aluminium sheet surface that was subjected to cataphoretic painting and priming exhibits better adhesive properties. It has a higher value of both surface free energy and its dispersion and polar components compared to the surface that was only subjected to degreasing.
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Recent developments and trends in the field of eco-efficient bio-based adhesives are reviewed.Eco-efficient means efficient with regard to both ecological and economical aspects.The recent developments in tannin adhesives without ...
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Recent developments and trends in the field of eco-efficient bio-based adhesives are reviewed.Eco-efficient means efficient with regard to both ecological and economical aspects.The recent developments in tannin adhesives without the use of any aldehyde-yielding compounds under the conditions of use,or even without the use of any hardeners,are described.Lignin adhesives are discussed next.Developments in protein adhesives,particularly the recent development in soy protein adhesives,are then addressed.Several new trends in carbohydrate adhesives,namely as modifiers of existing adhesives,by forming degradation compounds such as furanic compounds which can then be used as adhesives building blocks,and directly as wood adhesives,even in the form of liquified wood,are addressed.Unsaturated oil adhesives based on epoxidized unsaturated vegetable oils are also described,as well as an example of cashew nut shell oil modified by a new and inexpensive method of ozonolysis to yield an adhesive by self-condensation of the material.The review addresses last the new process of solid wood welding by mechanical friction without the use of any adhesive,in which the wood interfacial region itself is used as the binder.
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