ABSTRACTS
The following is a list of the abstracts for papers which will be presented in the INTERNATIONAL SYMPOSIUM ON HIGH TECH ADHESIVES AND ADHESIVE JOINTS: TESTING, CHARACTERIZATION AND APPLICATIONS to be held at the Hilton Savannah DeSoto Hotel, Savannah, GA, December 8-10, 2004. The listing is alphabetical by presenting author. This list is updated continually to add abstracts as they become available and make appropriate corrections. This list may be conveniently searched by using the editor provided with most popular browsers (e.g. Microsoft Explorer, Netscape, ... etc.)
Soyprotein Adhesives: Effect of Additives on the Properties
(Abstract not yet available)
Assessment and Prediction of Mechanical Long-term Properties of Adhesive With High Plasticity
Life prediction for adhesive joints employing laboratory tests requiring only days, weeks, or months is a complex problem. The tests are carried out with the hope of simulating important effects that may happen to a joint during its lifetime. Much experience is needed to understand the test concepts, carry out the tests, and evaluate the results. Initial strength values of bonded joints, such as shear or peel properties, are obtainable from the adhesive manufacturers or the literature. They are useful to compare different adhesives and to demonstrate the effect of parameters such as bond line thickness, overlap length or curing conditions, and, in some cases, the surface state. Due to the specific network structure of elastomeric adhesives their viscoelastic-plastic deformation behavior is strongly time- and temperature dependent. Therefore the main objective of this paper is to investigate the viscous properties of elastomer-based adhesives and to suggest concepts on how to use these results in design and engineering of adhesives joints with enhanced plasticity.
1) Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8527, JAPAN
2) University of Yamanashi, 4-3-11 Kakeda, Kofu, Yamanashi 400-8511, JAPAN
A FEM Stress Analysis and Strength Estimation of Stepped-lap Adhesive Joints under Static Bending Moments
The stress distributions in stepped-lap adhesive joints subjected to static bending moments are analyzed using three-dimensional finite-element calculations. The FEM code name employed is ANSYS. The effects of Young's modulus of the adhesive, adhesive thickness, a number of steps and scarf angle of the adherend on the stress distributions at the adhesive interfaces are examined in elastic deformation range. An optimal design method for increasing the joint strength of the stepped-lap adhesive joints under static bending moments is proposed from the comparisons of the effects of the above factors. As the results, it is found that the maximum value of the maximum principal stress 1 occurs at the edge of the butted adhesive interfaces. It is also observed that the maximum value of the stress 1 decreases as Young's modulus of the adhesive increases. In addition, the joint strength is estimated using three-dimensional FEM calculations in elasto-plastic deformation range. For the verification of the FEM calculations, the experiments were carried out to measure the strains in the joints under static bending moments using strain gauges. A fairly good agreement is observed between the numerical and the measured results concerning the strains.
1) Division of Mechanical Engineering, Osaka University of Education,Asahigaoka, Kashiwara city, Osaka 582-8582, JAPAN
2) Department of Applied Chemistry, Osaka Institute of Technology
Ohmiya, Asahi-ku, Osaka 535-8585, JAPAN
3) Division of Material Technology, Technical Research Institute of Osaka
Prefecture, Aayumino Izumi City, Osaka 594-11577, JAPAN
R-curve Behavior of CTBN and Cross-linked Rubber Particles Modified Epoxy Adhesives under Mode I Loading
Rubber-modified epoxy adhesives are attracted special attention because of satisfying high static strength and high toughness simultaneously. A large number of studies have been conducted on fracture toughness of several types of adhesive joints bonded by the rubber-modified resins. In most studies on rubber-modified epoxies, when the energy release rate reaches a critical value, the crack is observed to propagate rapidly. Recently, it has been reported that an increase in the plastic deformability of the matrix phase or in the content of rubber particles brings about gradually crack propagation of the adhesive joint bonded by the rubber-modified epoxy resins. For the adhesively bonded joints, however, the behavior of crack propagation is scarcely investigated. In the present work, the crack propagation behavior of two types of rubber-modified epoxy adhesives was investigated : the one is modified with CTBN and the other is with cross-linked rubber particles, where DCB specimens were used for examining the crack propagation behavior under mode 1 loading. The test data were illustrated as J-R curves. When compared the J-R curves bonded by the two adhesives, it is observed that the gradient of the cross-linked rubber particles modified adhesives is steeper than that of CTBN modified adhesive. To elucidate the difference between the gradients for the two adhesives, the elastic-plastic finite element analysis was conducted, where Gurson $B!G (Bs constitutive equation was applied to the analysis ; also, we considered that for the CTBN modified adhesive the rubber particles act as initial voids, while the nucleation of rubber particles was taken into account for the cross-linked rubber particles modified adhesives. It was found that the difference between the J-R curves could be explained from the characteristics of calculated void-volume fraction.
*To whom all corresponding should be addressed.
a) Key Laboratory for Advanced Metallic Materials Research and Processing Technology of Guangdong Province, South China University of Technology, Guangzhou 510640, P.R. CHINA
b) Department of Chemical Engineering, Iwate University, Morioka 020-8551, JAPAN
Polymer Plating of Triazine Dithiols on Magnesium Alloy And Their Direct Adhesion to Plastic
Polymer plating of triazine dithiols such as 1,3,5-triazine-2,4,6--trithiol monosodium (TTN), 6-diallylamino-1,3,5-triazine-2,4-dithiol monosodium (DAN) and 6-dipropylamino-1,3,5-triazine-2,4-dithiol monosodium (PN) on the surfaces of magnesium alloy AZ91 has been investigated to provide adhesion property with poly(phenylene sulfide) (PPS). TTN yielded three-dimensioned polymer films with a large amount of high reactive S-S bonds and a small amount of SH groups on magnesium alloy surfaces. DAN provided three-dimensionalized polymer films with a small amount of SH groups, high reactive S-S bonds and allylic groups on the surfaces. PN gave a linear polymer with a large amount of low reactive S-S bonds to PPS. Polymer films obtained from TTN showed the highest adhesion property in the three kinds of polymer films, because they have three-dimensioned polymer films with a large amount of high reactive S-S bonds on magnesium alloy surfaces. The current density of 5 A/m2 brought about high adhesion strength in the direct adhesion of PPS to polymer-plated magnesium alloy, because it provides favorite surface property for adhesion of PPS to polymer-plated magnesium alloys. Tensile shear strength was influenced by molding and cylinder temperatures, because both factors relate to the formation of chemical bonds at the interface between PPS and polymer films formed on magnesium alloys. The reaction of PPS with S-S bonds on polymer-plated magnesium alloy in a naphthalene chloride solution at 413 K was confirmed by using XPS analysis.
GERMANY
Identification and Determination of Adequate Material Parameters Essential for the Numerical Simulation of High-Tech Adhesive Joints
Mathematical modelling is well established in all industries. The use of adhesively bonded joints is increasing, especially at lightweight constructions. For a reliable simulation of bonded components the mechanical behaviour of the joint under operational conditions must be known. Needful material parameters of the adhesive typically are taken out of data sheets or are determined according to available norms and standards. These practices mostly disregard the heavily anisotropic behaviour of the adhesive in the interconnection, especially at thin layers. This leads to considerable false estimation of the bond line strength.
Now methods have been developed allowing the determination of the stress-strain behaviour of adhesively bonded joints close to reality. Tests cover mono- as well as bi-axial loading under static and dynamic conditions. Service stresses caused by temperature, internal pressure and medium flow are implemented. The procedures allocate demanded material parameters for a better approach of numerical models to real applications.
1) School of Materials Science and Engineering, Georgia Institute of
Technology, 771 Ferst Dr NW, Atlanta, GA 30332-0245
2) National Institute for Lasers, Plasma and Radiation Physics, P.O. Box
MG-36, RO-077125, Bucharest-Magurele, ROMANIA
3) School of Chemistry and Biochemistry, Georgia Institute of Technology,
Atlanta, GA 30332-0400
4) Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084
5) University of Bucharest, Faculty of Physics, P.O. Box MG-11, 3NanoÇôSAE, Bucharest-Magurele, ROMANIA
6) US Naval Research Laboratory, Washington, D.C. 20375-5345
Matrix Assisted Pulsed Laser Evaporation of Mussel Adhesive Protein Thin Films
We have demonstrated successful growth of mussel adhesive protein analog (DOPA modified- PEO-PPO-PEO block copolymer) thin films using matrix assisted pulsed laser evaporation (MAPLE). The MAPLE- deposited thin films were examined using Fourier transformed infrared spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. We have demonstrated that the main functional groups of the mussel adhesive protein analog are present in the transferred film. These adhesive materials have several potential medical and marine applications.
1) Materials and Manufacturing Laboratory, Department of Mechanical Engineering, and Mechanics, Lehigh University, Bethlehem, PA 18015
2) Department of Polymer Engineering, The University of Akron, Akron, OH 44325-0301
A Comprehensive Fatigue Life Predictive Model for Joints Bonded Using a Silver-Filled Electronically Conductive Adhesive
This paper describes a novel fatigue-life prediction methodology aimed at providing the design engineer a practical life predictive tool using experimental data for constant loading cyclic fatigue under mechanical or thermal loading conditions. This encompasses an integrated approach to joint testing, analysis, and modeling. Utilizing the proposed methodologies, we aim to predict the changes in fatigue life of the adhesive, based on the whole spectrum of test variables including temperature, humidity, and load-ratio. For this purpose, joints were prepared using stainless steel adherends bonded with a commercial silver-filled electronically conductive adhesive, and tested under monotonic and cyclic fatigue conditions, at 28oC, 20% relative humidity, 50oC, 90oC, and elevated humidity levels. Fatigue load vs. life (P-N) curves were generated using two specimen geometries at two different load-ratios (R), at a cyclic frequency of 150 Hz. Using the experimental data, a life predictive methodology was developed and validated based on superposition methods. Furthermore, the usefulness of the above mentioned fatigue life predictive capability was extended to varying stress states.
1) Materials and Manufacturing Laboratory, Department of Mechanical Engineering, and Mechanics, Lehigh University, Bethlehem, PA 18015
2) Department of Polymer Engineering, The University of Akron, Akron, OH 44325-0301
A Novel Cumulative Fatigue Damage Model for Assessing Residual Fatigue Life Under Variable Loading for Joints Bonded Using a Silver-Filled Electronically Conductive Adhesive
This paper describes a novel cumulative fatigue damage life predictive model aimed at providing the design engineer a fatigue life predictive tool using experimental data. This encompasses an integrated approach of joint testing, analysis, and modeling. . For this purpose, joints were prepared using stainless steel adherends bonded with a commercial silver-filled electronically conductive adhesive, and tested under monotonic and cyclic fatigue conditions, at 28oC, 20% Relative Humidity. Fatigue load vs. life (P-N) curves were generated at two different load-ratios (R), namely 0.1, and 0.5, at a cyclic frequency of 150 Hz, and fatigue life and failure behavior due to cumulative fatigue damage were assessed using a novel experimental program. Experimental results reveled that the combination of lower load-ratio (Pmin/Pmax), and higher applied load have the most detrimental effect on the failure of the joint, and most of the damage on the joint occurs during the latter part of the fatigue process. Finally, a novel analytical model for fatigue life prediction was proposed using experimental data, and a detailed stress analysis.
Correlation of Pullout Strength of Silver Wire Embedded in an Adhesive Matrix to Surface Mass Loss by Silver Migration
The substantial growth in electronics industry has created a need for environmental and user friendly alternatives to tin / lead (Sn/Pb) solders for attaching encapsulated surface mount components on rigid and flexible printed circuit boards. Electronically Conductive Adhesives (ECAs) have been explored in this manner to establish mechanical as well as electrical joints between printed circuit board and surface mount components. Applications of conductive adhesive are limited due to serious concerns associated with the long-term reliability data of current commercial ECAs. One critical concern in wire bonding applications is the significant decrease in the bond strength and consequent loss of the conducting properties of adhesive due to silver migration. In this study an effort is made to understand and model long-term silver migration phenomenon with respect to different parameters (duration of the migration, dry and wet conditions), and pull-out strength of silver wire embedded in an epoxy adhesive matrix. Morphology of embedded silver wire after migration and pull-out was also studied using scanning electron micrographs. Migration area increased with the duration of migration, and reduction in the pull-out strength was significant in wet condition as compared to dry condition. The increase in migration area was consistent with the reduction in pull-out strength in both wet and dry conditions.
1) Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8527, JAPAN
2) University of Yamanashi, 4-3-11 Kakeda, Kofu, Yamanashi 400-8511, JAPAN
Stress Analysis and Strength Estimation of Butt Adhesive Joints with Fillers under Static Tensile Loadings
The stress distributions in butt adhesive joints of similar adherends with fillers subjected to static tensile loadings are analyzed using finite-element calculations and the two-dimensional theory of elasticity. The FEM code name employed is ANSYS. The effects of Young's modulus, the location and size of the fillers on the stress distributions around the fillers at the adhesive interface are examined. An optimal design method for increasing joint strength of butt adhesive joints with fillers under static loadings is proposed from the comparisons of the effects of the above factors. As the results, it is found that the maximum principal stress 1 becomes maximum at the edges of the adhesive interfaces. It is also observed that the maximum value of the stress 1 decreases as the number of fillers increases. In additions, the strain distributions at the adhesive interface in the joints with fillers are also analyzed in elasto-plastic deformation range using three-dimensional FEM calculations. A method for estimating the joint strength is proposed using the obtained strain distributions at the adhesive interfaces. For verification of the FEM calculations, the experiments were carried out to measure the strains in the butt adhesive joints with fillers under static tensile loadings using strain gauges. The numerical results are compared with the experimental results.
Plant Protein Adhesives and Performance
A key component of crops is storage proteins. Based on USDA statistics, U.S. has potential to produce 140 billion lb plant proteins. Besides food and feed applications, these proteins have great potential for adhesive and other nonfood applications.
In general, most proteins have adhesive property. However, some proteins have higher adhesive strength and higher water resistance than others. Proteins from different sources present varied composition and structures, and consequently different adhesive performance. Adhesive performance can also be modified using physical, chemical, and enzymatic methods. This paper discusses recent research efforts on plant protein based adhesives, especially soy protein, and their potentials for wood and nonwood applications, protein structure and adhesive performance, and latex like adhesives derived from proteins.
Effects of Aging and Environment on Bonding Strength of Polyurethane Based Desmodur-VTKA Adhesive in Some Wood Materials
The aim of this study is to determine whether a special glue material existing in market made strength joint cold and hot water and boiling conditions in wooden materials or not, the selected glue material is called Desmodur-VTKA (i.e.polymarine) and based on polyurethane. For this purpose, oriental beech (Fagus orientalis lipsky), oak (Qercus petraea spp.) and scotch pine (Pinus sylvestris lipsky) woods were chosen as the test materials since these are widely used in furniture, decoration and building. Air conditionary, waiting in cold water, waiting in hot water, boiling and recurrence boiling operations have been applied to the samples which are glued with Desmodur-VTKA polymarine according to the procedure of BS EN 204 standards. Glue was passed this test successfully. The shear strength test was applied to the connection surface of samples according to the procedure of BS EN 205 standards. The test result showed that the highest shear strength (10.723 N/mm2) was obtained in oak with unprocessed samples. And the lowest shear strength (1.540 N/mm2) was obtained in oak after the all processed.
1) Technical Education Faculty of Zonguldak Karaelmas University, Karabük, TURKEY
2) Technical Programs, Safranbolu College, Zonguldak Karaelmas University, TURKEY
Improvement of Laminated Wood Material Properties by Impregnation with Some Chemicals
Scotc pine and eastern beech (for outer ply) and poplar samples (for core ply), sawed longitudinally were impregnated with tanalith-C 3310, borax, boric acid, borax+boric acid and di-ammonium phosphate chemicals according to procedure in the ASTM-D 1413-76 standards. Laminated wood materials (LWM) were prepared by using phenol formaldehyde (PF) and melamine formaldehyde (MF) adhesives. In the experiments, weight gains, density, compression and bending strength, modulus of elasticity (MOE), bonding strength properties were determined. Weight gains of 17.6 % - 71.2 % were obtained after polymerization for 96 h. While scotc pine LWM bonded with phenol formaldehyde and impregnated with T-C 3310 gave the highest weight gains (71.2 %), beech LWM bonded with PF showed the lowest value (17.6 %). The highest density as 24 %-25 % for beech and 21 % was obtained for pine LWM impregnated with T-C 3310 chemical. A maximum antiswell efficiency (ASE) of 12 % was obtained for beech. Both longitudinal compression and bending strength of wood-polymer composite gave important reducement due to their high weight gains (WPG). Improvement of 19 % in MOE test was also achieved for beech LWM samples bonded PF adhesive. The specimens impregnated with mixture of Boric acid and T-C 3310 showed a decreasing effect, specially, bonding strength of 26 % for beech and 21.9 % for pine after a weight gains test of 96 h. Both the densities and pH values of impregnation chemicals were not changed.
New Rheometer Measurement Geometry and the Characterisation of Solvent Absorption Effects in the Cure Behavior of Adhesives in Wood Joints
Step 1: A new type of filler for Phenol-Resorcinol-Formaldehyde (PRF) adhesives
A special suspension polymerisation technique was used to synthesize polymer microbeads in the micrometer range. These polymer microbeads were used as a novel filler for PRF resins and enabled extremely high substitution levels (up to 60 wt%), while retaining good all round performance.
Step 2: Rheometer measurements for online curing monitoring
The response behaviour of an adhesive to the application of stress should relate to application and performance characteristics. It therefore should be possible to use a rheometer to characterise resin application and curing behaviour. However, there is one fundamental shortcoming: the standard metal measuring geometries don't allow any solvent uptake and thus behave very differently to wooden surfaces.
Step 3: Development of a new rheometer geometry
A new rheometer geometry was developed which enables the effects of solvent uptake due to diffusion and capillary forces to be monitored. Using this geometry, the characteristics of resins made from a standard commercial resin, but modified with the newly microbead developed filler, were analyzed. Highly filled resins of this type showed very good tack development and enabled significant bonding strengths to be achieved, even without a chemical hardening reaction. It became obvious that the solvent uptake is driving the overall performance in the first one or two hours at ambient temperature.
*To whom correspondence should be addressed: Tel.: +64 7 343 5419;
fax: +64 7 348 0952; E-mail address: michael.witt@forestresearch.co.nz