Adhesion Theories and Effect of Surface Roughness on Energy Estimation and Wettability of Polymeric Composites Bonded Joints: A-Review (original) (raw)
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Influence of Adherend Surface Roughness on the Adhesive Bond Strength
Latin American Journal of Solids and Structures, 2016
Surface treatment of the adherends prior to adhesive bonding plays an important role in the enhancing of strength and durability of bonded joints. In this work, an investigation on effect of adherend surface roughness on adhesive bond strength was performed. Single strap joints with different adherends (mild steel and aluminium) bonded with an epoxy resin (Araldite® 2015) were tested. The adherend surface was treated by mechanical abrasion process using an emery paper. Contact angle measurement and SEM analysis to understand the wettability and the failure mechanism of the joints were performed. It was found that an optimum surface roughness exists for a maximum bonding strength and the roughness range depends on the adherend material. The joint strength changes are associated not only simply by the increased bonding area, surface texture or mechanical interlocking, but also by the chemical characteristics of the surface and the chemical bond between them.
Polymers and lightweight composites rapidly replace metals in high-tech engineering applications in automotive, aerospace, shipbuilding, civil and other engineering applications. Due to chemical inertness, hydrophobicity, surface contamination and migrating functional and processing additives, most polymers require surface modification to ascertain high strength and reliability of bonded products. In structural bonding, the key objective is creation of permanent bond between bonded elements. The overarching aim is creating such strong adhesion forces between bonded material and adhesive that the bond becomes unbreakable and the adhesive or substrate become the weakest element of the structure, thus enabling application of verifiable engineering design principles ascertaining reliable performance of structures throughout entire service life under the influence of all static, dynamic and environmental loads and impacts. Theoretical and engineering aspects of the problem, including criteria for attaining such bond properties, including experimental data, are comprehensively discussed in this paper. Examples of industrial applications of the technology are provided.
Influence of Acrylic Adhesive Viscosity and Surface Roughness on the Properties of Adhesive Joint
The Journal of Adhesion, 2015
The aim of this paper is to study the influence of viscosity and surface roughness on the wetting and their effect on the bond strength. For this purpose, an acrylic adhesive with different viscosities was synthesized and some properties, such as viscosity and surface tension, were studied before adhesive curing took place. Furthermore, the contact angle and the lap-shear strength were analyzed using aluminum adherends with two different roughnesses. Scanning electron microscopy was used to determine the effect of the viscosity and the roughness on the joint interface. The results showed that the adhesive exhibits an optimal value of viscosity. Below this value, at low viscosities, the low neoprene content produces poor bond strength due to the reduced toughness of the adhesive. Additionally, it also produces a high shrinkage during curing, which leads to the apparition of residual stresses that weakens the interfacial strength. However, once the optimum value, an increase in the viscosity produces a negative effect on the joint strength as a result of an important decrease in the wettability.
Adherend surface roughness effect on the mechanical response of adhesive joints
arXiv: Applied Physics, 2020
The present contribution focuses on the effect of adherend surface roughness on the strength of adhesive joints, which are particularly cost-effective and extensively applied in a wide range of industrial applications. However, the reliability of such solutions is a critical concern for the integrity of commercial products. To gain a deeper understanding on the effect of roughness, an extensive experimental campaign is proposed, where thermoplastic substrates are produced with a specified roughness, whose characterization has been performed using a confocal profilometer. Elastic strips are then bonded onto such substrates using Silicone adhesive while controlling the adhesive thickness. Peeling tests are finally carried out and the effects of joint parameters such as surface roughness, adhesive thickness, and loading rate are discussed in detail. Eventually, it is demonstrated that the surface roughness can increase the adhesion energy of joints depending on the value of a ratio bet...
The Bulletin of the Polytechnic Institute of Jassy, Construction. Architecture Section, 2016
The adhesive bonding is one of the most suitable joining technique for structures made of composite materials. Adhesive bonding of fiber reinforced polymer (FRP) composite products is utilised in various applications such as: strengthening techniques, reparing the surface of different FRP elements and as a general alternative, when mechanical fastenings are not suitable. The adhesion between the adhesive and the adherents arises from the fact that all materials have attraction forces acting between their atoms and molecules. The bond strength depends on the intensity of the attraction forces and on the interaction between the adhesive and the surfaces of the adherents. This paper presents a review of the existing adhesion theories suitable for FRP composite products. Also, varios research programs related to the adhesion mecanisms between FRP elements are presented in this paper.
Progress in Organic Coatings, 1988
The influence of a thin adhesive layer (AL) of a polymer on the wet adhesion of an epoxy coating on an aluminium substrate has been studied by the peel and tape test method. It is shown that thin layers considerably improve the stability of adhesive joints in the presence of water. The mechanism of this improvement and the mechanical properties required for such thin layers are discussed. Some experimental evidence for improved wet adhesion of polymer binders to an aluminium support is presented and the mechanism explained. These results on interfacial processes contribute to a better understanding of the mechanism of adhesion.
Influence of nano toughened epoxies in the bonding characteristics of adhesive joints
Adhesive joints are proving to be an excellent solution for joining similar or dissimilar substrates due to their elevated and enhanced bonding characteristics. They are found to frequently replace the traditional joints due to their ability to distribute load. Hence, the substantiation of the joint strength lies in the strengthening of the adhesion characteristics. Among the many parameters which promote the adhesive strengthening, the fusion of nano particles (NPs) has occupied a prominent area of research due to their promotional ability to enhance the mechanical properties of the joint. Hence the need is there to conduct a comprehensive review into the types of NPs, methodologies of dispersion, the % by wt of NP addition, and the changes that take place in the mechanical and chemical perspectives in the adhesive layer as well as the interface zones between the adhesive and the substrate. So, the paper is committed to conduct a comprehensive but relevant review in this direction of adhesive strengthening paving the way for adhesive joint strength substantiation.
Quantitative determination of interfacial adhesion in composites with strong bonding
European Polymer Journal, 2010
An approach was proposed for the quantitative determination of adhesion strength in composites, in which adhesion is created by other mechanisms than secondary interactions. The approach is based upon a model, which gives debonding stress as a function of interfacial adhesion. Debonding stress was determined by acoustic emission experiments. The mechanism of deformation was checked by SEM experiments and the approach was verified on composites with known interfacial adhesion. The results showed that the use of functionalized polymer in PP/CaCO 3 composites resulted in adhesion strength one order of magnitude larger than without the coupling agent. The application of various surface modification techniques in PP/glass bead composites yielded different adhesion values covering a range of about one order of magnitude. The quantitative determination of interfacial adhesion makes possible the design and optimization of most surface modification techniques in particulate filled and short fiber reinforced composites.
Effect of Surface Pre-treatments and Ageing on the Adhesive Strength of Polymer Joints
Polymer Korea
In this study, the effects of pre-treatment and ageing on the adhesive strength of polymer materials PE, PP and PVC are investigated experimentally. The experiments are carried out under mechanical abrasion, corona discharge and plasma methods at temperatures of-20, 0, 20 o C and ageing for different times for 30, 60, 90 days at 50 o C. The shear stress increased for PVC at-20 o C, using both corona discharge and plasma methods. The shear strength of adhesively bonded joints reduced at an ageing temperature of 50 o C and it continued to gradually reduce during ageing time from 30 to 90 days. The lowest strength was obtained at 50 o C and 90 days' ageing.
Adhesive bonding of dissimilar materials
Machines. Technologies. Materials., 2020
The paper is focused on research results of dissimilar materials joining by adhesive bonding. Galvanized and non-galvanized steel sheets with a thickness of 0.8 mm were joined together. To compare the effect of the presence or absence of the Zn layer on the strength of the adhesive joints, control joints were made, consisting only of galvanized and only of non-galvanized materials. The materials were joined on one hand without any surface preparation, and on the other hand prepared by degreasing and mechanical roughening with sandpaper. Epoxy/PVC-Polymerblend adhesive with glass beads was used for bonding to check the thickness of the adhesive. The tensile lap-shear strength was tested according to DIN EN 1465. The joints made of galvanized materials only proved the highest, the joints made of nongalvanized materials only proved the lowest shear strength. The mixed joints did not reach the joint strength of galvanized materials, but exceeded the joint strength of non-galvanized materials. The adhesion of the adhesive to non-galvanized substrates seems to be the limiting factor of the strength of mixed joints.