The following is a list of the abstracts for papers which will be presented in the INTERNATIONAL SYMPOSIUM ON ADHESIVES: SYNTHESIS, CHARACTERIZATION AND APPLICATIONS 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.)

Saburo Akiyama; Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-26-16, Nakacho, Koganei-shi, Tokyo 184-8588 JAPAN

A New PSA Film Without Backing Polymer Made by Domain Graded Method

The gradient structures formed in the thin films are quite interesting, if it develops new function. In this study, the domain graded polymer blend film has been constructed and confirmed with cross section EM in the casting film of fluorinated copolymer/2-ethylhexyl copolymer blend, where adhesive acrylate rich domains graded from bottom to air surface side. This means a new adhesive film without backing can be formed, where upper side covered no tacky matrix due to fluorinated copolymer. This graded structure could be effected by the difference of surface tension, Y and also solvent evaporation rate. Therefore, now instead of fluorinated copolymer, silicate-graft PMMA, which has the same low Y has also been used and taken the same domain graded results.

Ibraheem T. Badejo; Closure Medical Corporation, Raleigh, NC 27616

Cyanoacrylates in Medicine

The adhesive properties of cyanoacrylates were discovered by accident at a Tennessee Eastman Labs by a group of scientists led by Coover. Cyanoacrylates have the ability to rapidly polymerized and bond to many surfaces. The unique ability of cyanoacrylates to polymerize without a catalyst is attributed to the strongly electron withdrawing groups of the cyano (-CN) and the carboxyl (-COOR) moieties (structure below).

In 1965, Watson and Maguda made the first attempt to use industrial grade methyl cyanoacrylate in the clinically environment for tympanic membrane repair. This material was showed unacceptable tissue toxicity. Since then, further clinical studies have employed the use of higher homologues such as n-butylcyanoacylate which have shown very little to no tissue toxicity. On going research is being conducted on modifying the carboxyl moiety of the cyanoacrylate to improve its biodegradability and tissue toxicity.

Closure Medical Corporation is actively engaged in developing its proprietary cyanoacrylate technology into useful medical products to improve the treatment of various wound treatments and closures in medicine. In 1998, Closure Medical received the first FDA approval for the use of a formulated 2-octylcyanoacrylate (DERMABOND® * Topical Skin Adhesive) for the closure of lacerations. In 1999, Closure Medical received FDA approval for a proprietary cyanoacrylate formulation for the relief and treatment of oral ulcers. Also in 2000, Closure Medical completed human clinical trials for the use of its proprietary cyanoacrylate formulation for the treatment of minor cuts and abrasion.

This presentation will review the discovery, chemistry and the results of the above clinical studies and the use of cyanoacrylates in other clinical indications such as fixation of implants; non-surgical female sterilization; retinal repair; corneal repair; hair transplantation; brain arteriovenous malformation; dental surgery; closure of cerebrospinal fluid leaks; intestinal anastomnoses; and in veterinary medicine.

*DERMABOND® is a trademark of Ethicon, Inc.

Arthur J. Coury; Genzyme Corp., 1 Kendall Square, Cambridge, MA 02139-1562

Surgical Adhesives and Sealants for Topical and Implant Applications

Surgical adhesives and sealants are medical devices formed from liquid or solid substances applied to wounds to hold tissues together or prevent leaks. Together they comprise an emerging field of medical therapy and offer the clinician an alternative or supplement to sutures, staples and adhesive tapes. Adhesive and sealant precursor compositions can be of synthetic, natural or "hybrid" origin. When applied to tissue, they generally undergo or induce a chemical reaction, which produces a bond to the tissue and stabilizes the construct. The forces of attachment to the tissue can be the result of covalent, ionic or electrostatic interactions and generally involve a degree of mechanical interlock. Examples of chemical reactions induced upon application of the precursors include hardening of two part systems, photo-polymerization or moisture cure of one-part systems, coagulation of blood components and covalent coupling to tissue collagen. The intended duration of use of the adhesives and sealants can range from a few days to "permanent." Temporary devices are designed to degrade or slough in concert with the wound healing process and often produce excellent outcomes in terms of appearance, strength and functionality of the healed tissue. Attributes such as ease of application, safety, efficacy and applicability to a range of difficult wounds assure a growing role for surgical adhesives and sealants in modern medicine.

Russ Crook and Diane Guilfoyle1; 'Lucent Technologies Microelectronics Group, 9999 Hamilton Boulevard, Breinigsville, PA 18031-9359

1) Corning Incorporated, SP-PRO1, Coming, NY 14831

Contamination Insensitive UV Curable Adhesives Part II

We recently reported on the discovery of a family of UV curable epoxy siloxane resins with the unusual ability to bond to metal and glass surfaces that had been heavily contaminated. The contamination studies showed that when 304 stainless steel is precontarninated with either silicone or hydrocarbon release agents at 6.6 mg/sq.in. prior to bonding, no decrease in average lap shear strength was observed compared to the freshly cleaned adherends. Commercially available two part and UV curable adhesives could tolerate only 0.3mg/sq.in. above which they would physically falling apart in the bonding fixture. However, the average lap shear strength of the original formulation had average lap shear strengths that were approximately 5.52-6.89 MPa (800-1000 psi); too low to be of much use in most structural applications.

This paper will report on work that has continued on the development of these adhesive materials. Formulation has yielded a proprietary resin system that significantly increases the durability and strength of adhesive joints while over the original formulation while preserving the contamination insensitivity of the bond. The average lap shear strength of these resin systems now is approximately 15.2 MPa (2200 psi) with or without 5.0 rng/sq.in. of silicone mold release. After two weeks of 85%R.H. and 85C environmental aging, lap shear specimens made of precontaminated 304 stainless steel adherends with 5.0 mg/sq.in. of silicone grease had an average lap shear strength of 11.03 MPa (1600 psi). This represents a decrease of only 27% and still above many commercially available UV curable adhesives on clean 304 stainless steel.

Jeffrey Dormish and Reiner Witkowski*; Bayer Corporation, 100 Bayer Road, Pittsburgh, PA 15205

*Bayer AG, Dormagen, Germany

Polyurethane Dispersions for Adhesive Applications

This paper will provide an overview of aqueous polyurethane dispersions used in adhesive applications. It will contain a brief overview of common raw materials and production processes used for polyurethane dispersions, will review standard measures of performance and improvements possible upon crosslinking. The performance of solvent borne polyurethane adhesives will be used as a reference point. 'The examples used will focus on polyurethane dispersions suitable for bonding substrates such as, plasticized PVC.

Bruce Eu and Larry Salvati; Abbott Laboratories, D-9FT AP20, 100 Abbott Park, Abbott Park, IL 60064-6105

Why Adhesives Decrease Capillary Flow Rates in Lateral Flow Immunoassays? - a Materials Science Problem in Biotechnology

It has been widely recognized that inappropriate selection of adhesives in contact with nitrocellulose membranes of lateral flow immunoassays (rapid tests) will affect the stability of the capillary flow rates of these membranes. In the worst case, the flow time of the membranes can increase from a few minutes to almost half an hour after a few months of storage at room temperatures. This slow down in capillary flow greatly reduces the shelf life of rapid tests. The phenomenon has been attributed to either surfactant migration from the membranes to the adhesives or the hydrophobicity of the adhesive although the root cause for this problem was never identified. In this study, the data indicate that the slow down in capillary flow is controlled by the rheology of the adhesives rather than the chemical properties of the adhesives as one previously thought. The rheology of the adhesive can be quantified by measuring the adhesive's glass transition temperature (Tg) and storage modulus (G') by thermally stimulated current (TSC) and dynamic mechanical analyzer (DMA), respectively. A strong correlation was established between either the Tg or G' of the adhesive with the decrease in capillary flow rates. Adhesives with low Tg or G' will creep into membranes faster by the action of the surface energy of the membranes, this renders the membranes more hydrophobic and decreases the flow rate. The creep of adhesives was also supported by scanning electron microscope (SEM) examination on the cross section of the laminated membranes. X-ray Photoelectron Spectroscopy (XPS) results showed that migration of uncured silicone and surfactant from adhesives to membranes has a dramatic impact on the performance of these tests. Appropriate materials selection criteria for lateral flow immunoassays will be discussed.

Jeffrey T. Fields, Stephanie A. Stirn and Douglas A. Lange; Franklin International, 2020 Bruck St, Columbus, OH 43207

1-Part Polyurethanes for Fingerjointing Softwoods

The applications for polyurethane adhesives continue to grow due to the variable properties that can be achieved with these products. One area where they are gaining acceptance is in fingerjointing softwood shorts into various lumber products. PUR adhesives are being tested and used to address fiber recovery inefficiencies and process restrictions. This paper summarizes findings from multiple studies that have focused on application of PUR adhesive technology to this industry. These studies include bonding of frozen lumber, "green" lumber, variable moisture content lumber, rate of strength development, structural bonding, and pressure treatment. The findings indicate that PUR adhesives can offer viable solutions for most of these applications with some restrictions. Further study is recommended to better understand this new technology for wood bonding.

Freddy Romm1 , Oleg Figovsky2 and V. Karchevsky1

1) POLYMATE Ltd., POB 73, Migdal Emek, 10550 Israel

2) EUROTECH Ltd., 10306 Eaton Pl., Suite 220, Fairfax, VA 22030

Combined Thermodynamic / Monte-carlo Modeling of the Adhesive Bond Formation in a Microporous System

The model of the adhesive bond formation in a microporous system is

solved using a numerical approach based on the combination of the

thermodynamic model of microporous structure formation, described in

previous publications, with the casual model in the Monte-Carlo form. The

microporous structure is modeled as a cellular system. The thermodynamic

model provides the general equations showing the preferable group of cells

incoming to the adhesive interaction, with the probability of such

interaction, and the concrete cell is selected eventually, by the

Monte-Carlo method.

The proposed model is used for the evaluation of the surface area

corresponding to the adhesive bonds. The criterion for the better adhesion

- the maximum of the two-phase contact surface area.

Fernando Galembeck; Instituto de Quimica, UNICAMP, C.P. 6154, 13083-970 Campinas(SP), BRAZIL

Latex Particle Microchemistry and Macroionics, Determined by Spectroscopic Imaging (ESI-TEM) and Scanning Electric Potential Microscopy

(Abstract not yet available)

Valery F. Godinez-Azcuaga1, Richard D. Finlayson1, Ronnie K. Miller1, and Basavaraju B. Raju2

1) Physical Acoustics Corporation, 195 Clarksville Road, Princeton Junction NJ 08550-5303

2)U,S. Army Tank-Automotive and Armaments Command, Warren MI 48397-5000

Acousto-Ultrasonic NDE of Thick Hybrid Composites

Multi-layered composite armor plates are currently used in prototype armored vehicles. In order to ensure their integrity these plates need to be inspected nondestructively. The Acousto-Ultrasonic technique has demonstrated the ability to detect and image defects in thick hybridcomposite armor plates, A wave propagation model is used to predict the acoustic response of thick hybrid composite tumor in the frequency domain. With this information, inspection parameters such as incidence angle and frequency of the interrogating acoustic waves have been optimized for detection of delaminations at different depths within the composite, and a multisensor probe has been specially designed for this purpose. The Acousto-Ultrasonic system includes a very precise computer controlled scanning bridge, which can be attached to vertical surfaces by means of suction cups connected to a small, low weight, high power vacuum pump. It also includes an arbitrary waveform generator with a multiplexer that enables the board to send excitation pulses to each one of the acoustic sensors, and a multi-channel acoustic emission board capable of collecting and processing the acoustic signals in real time, The system is easy to transport, setup, use, and it is designed to be rugged and reliable. It is capable of generating C, scan images of composite armor plates with axis to only the external surface of the plates. The system can scan the rumor composite either, automatically, in places where the scanning budge can be attached to the vehicle, or manually in areas where access is limited by using the multisensor probe as a hand-held scanning device, In this case, the position of the probe is fed to the AU instrument by a 'wireless position tracking system. The software that controls the system is capable of generating simultaneous C-scans, resulting fxorn the combination of the pulsing acid receiving sensors. The system also includes controls for selecting the length, frequency, and shape of the signal used to excite the pulsing sensors. C-scans of samples with simulated delaminations are presented.

Jangsoon Kim and Earle Ryba; Deptartment of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802

Effect of the Crystalline Interphase on the Adhesion of Polyurethane to Aluminum

A study of the nature of the crystalline interphase in polyurethane/aluminum bonds and its effect on the adhesion strength is in progress. Polyurethanes with three OH numbers were bonded to aluminum by solution casting. The nature of the fracture surface upon tape peeling of the polymer was examined microscopically, and the bond strength was measuring using indentation debonding. It was found that the adhesion strength was related to the number density of polyurethane spherulites formed at the interface. Atomic force microscopy (AFM) was used to examine the shapes and orientation of these polymer crystals. Very careful sample preparation was carried out by washing and rinsing with a solvent. AFM images of the resulting residues on the aluminum surface showed a discernible initial stage of polyurethane crystallization, which begins on the Al surface by heterogeneous nucleation. Sheaf-like spherulite formation was observed, and ordering of the polymer particles was found.

The presence of the polyurethane spherulites on the aluminum surface also affects water transmission by the bond. Water vapor absorption was found to be dependent upon the area fraction and size of the spherulites.

Jin Kook Kim and Dai Gil Lee;Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, ME3221, Gusong-dong, Yusung-gu, Taejon-shi, Korea 305-701

Thermal Characteristics of Tubular Single Lap Adhesive Joints under Axial Loads

When an adhesive joint is exposed to high environmental temperature, the tensile load capability of the adhesive joint decreases because the elastic modulus and failure strength of structural adhesive decrease. In this paper, the elastic modulus and failure strength of adhesives as well as the tensile load capability of tubular single lap adhesive joints were experimentally and theoretically investigated with respect to the volume fraction of filler, the environmental temperature and the ratio of cross sectional area of steel adherends. Also the tensile load capability of adhesive joint was predicted by FEM analysis with respect to the volume fraction of filler and ratio of cross sectional area of steel adherends. Two types of fillers such as Al2O3(alumina) and chopped fiber E glass were used. From the experiment, it was found that the elastic modulus and failure strength of the adhesive increased in accordance with the increase of volume fraction of filler and decreased with the environmental temperature rise. Also it was found that the tensile load capability of the tubular single lap adhesive joint decreased as the environmental temperature increased but the tensile load capability of the tubular single lap adhesive joint had no correlation with the volume fraction of filler because the fabrication thermal residual stresses was generated by CTE difference between the adherend and adhesive. Also it was found that the tensile load capability of the tubular single lap adhesively bonded joint was maximum when the cross sectional areas of steel adherends were same.

E. Siores1, H. S. Ku1, J. A. R. Ball2, and M. MacRobert1

1) Industrial Research Institute Swinburne (IRIS), Swinburne University of Technology (SUT), Henry Street, Hawthorn, VIC 3122, Australia.

2) Electrical, Electronic & Computer Engineering, University of Southern Queensland (USQ), West Street, Toowoomba, 4350 Australia.

Applications of Variable Frequency Microwave (VFM) On Adhesives

Microwave processing of adhesives is a relatively new technology advancement alternative that provides new approaches for enhancing material properties as well as economic advantages through energy savings and accelerated product development. However, the most commonly used facilities for microwave processing materials are of fixed frequency, eg 2.45 GHz. This paper presents a state-of-the-art review of microwave technologies, processing methods and industrial applications, using variable frequency microwave (VFM) facilities. The technique offers rapid, uniform and selective heating over a large volume at a high energy coupling efficiency. This is accomplished using a preselected bandwidth sweeping around a central frequency employing tunable frequency sources such as travelling wave tubes (TWTs) as the microwave power amplifier. Successful applications of these modern facilities by the authors include the characterisation of glass or carbon fibre reinforced thermoplastic matrix composites, the characterisation of primers, eg two-part five-minute rapid araldite, and the joining of the above mentioned composite materials with, or without, primers. Microwave energy has been used to rapidly cure several types of two part epoxy based adhesives, eg rapid araldite. Bond strengths obtained using microwave techniques are compared with adhesives joints cured in ambient conditions.

Ludwik Liebler; ELF-ATOCHEM/CNRS, UMR 167, 95 Rue Danton B.P. 108, 92303 Levallois Cedex, FRANCE

Switchable Adhesives

(Abstract not yet Available)

Joseph J. Marcinko; Huntsman Polyurethanes, 286 Mantua Grove Road, West Deptford, NJ 08066

Exploring Isocyanate / Lignocellulosic Composite Adhesion

(Abstract not yet available)

F. Arán-Aís, A.M. Torró-Palau, A.C. Orgilés-Barceló; INESCOP, Footwear Research Institute, 03600 Elda, Alicante, Spain

T.P. Ferrándiz-Gomez, J.M. Martín-Martínez; Adhesion and Adhesives Laboratory, University of Alicante, 03080 Alicante, Spain

Improving Tack of Polyurethane Adhesives by Adding Rosin Resin as Internal Tackifier

Several thermoplastic polyurethane elastomers (TPUs) containing different hard/soft (h/s) segment ratios (1.05, 1.4) were prepared using the prepolymer method. MDI (dyphenylmethane-4,4'-diisocyanate) and polyadipate of 1,4-butanediol (Mw=2440) were reacted to produce a prepolymer containing free isocyanate at the end, to which a chain extender (rosin resin + 1,4-butanediol mixtures, 0-50%) was added. The main feature of this procedure was the addition of the rosin resin as internal tackifier to impart improved immediate adhesion to the TPUs. The TPUs obtained were characterized using gel permeation chromatography, FTIR and 1H-NMR spectroscopy, wide angle X-Ray diffraction, differential scanning calorimetry, stress controlled rheology and stress-strain measurements. The TPUs were used as raw material to prepare MEK solutions of polyurethane adhesives, which adhesion properties were obtained from T-peel tests of PVC/polyurethane adhesive/PVC and leather/polyurethane adhesive/PVC joints. The addition of a rosin resin as internal tackifier increased the average molecular weight, more markedly in the TPUs containing higher hard/soft segment ratios; furthermore the elastic and viscous moduli were decreased. An increase in the h/s segments ratio of the TPUs produced slower kinetics of crystallization and a high immediate T-peel strength. Finally, the increase in the rosin resin content in the chain extender mixture also produced an increase in the immediate T-peel strength.

Osama Musa; National Starch and Chemical, 10 Finderne Avenue, Bridgewater, NJ 08807

Novel Donor/Acceptor Chemistry for High-Performance Adhesives

The electronics packaging industry has always placed an emphasis on rapidly-curing, high-reliability adhesive materials. For many applications, epoxide-based formulations offer a number of advantages. However, some limitations of these systems (e.g. cure speed and moisture absorption) have led us to investigate alternate chemistry. In this presentation, some aspects of our work with "pseudo charge transfer" chemistry will be discussed. In these systems, an electron acceptor functionality forms a "charge transfer" complex with an electron-donor functionality.

Our synthetic approaches towards both electron-accepting and electron donating materials will be discussed. In addition, preliminary evaluation (e.g. curing kinetics, die shear strengths, and thermogravimetric weight loss) of these materials in prototype die attach formulations will be presented.

Donna M. Narsavage-Heald1 and Raymond A. Pearson2

1) Department of Chemistry, University of Scranton, Scranton, PA

2) Materials Science and Engineering, Lehigh University, Bethlehem, PA

Effect of Adhesion Promoters on the Wet Adhesive Strength of Epoxy to Glass

Several silane and titanate adhesion promoters were investigated for use with bisphenol F, imidazole cured epoxy resin on a glass substrate. The adhesion promoters were applied to the glass surface before applying the epoxy resin. Adhesion was measured using a double-cantilever beam test after exposure of the samples to 85 C and 85 % relative humidity. In the control sample (untreated glass), the adhesion dropped significantly after 4 days of exposure. As expected, the adhesion promoters allowed retention of adhesive strength. As a separate study, adhesion promoters were also added directly to the epoxy resin. Their effectiveness in retaining adhesion will be reported.

Dr. Richard Pethrick; Department of Pure & Applied Chemistry, University of Strathclyde, Thomas Graham Bldg., 295 Cathedral Street, Glasgow G1 1XL, UK

Dielectric Assessment of Ageing in Adhesive Bonded Structures

(Abstract not yet available)

C. Saikumar; Central Leather Research Institute, Adyar, Chennai 600 020, INDIA

Adhesives in Leather Industry - Perspectives for the Changing Needs

Adhesion is a surface physico - chemical phenomenon. The

nature of the adhesive joint and its physical properties depend strongly on the character of surface of the substrate and the interaction of adhesive with the surface. The adhesives are used in a far wider array of applications ranging from packaging to high tech areas of air-crafts and space-crafts. Leather is a unique bio-material. It has a three dimensional fibrillar textured Surface. The use of adhesives in leather industry has been mostly confined to the production of foot-wear and to some extent in leather goods and garments. Leather articles and footwear are made using synthetic dissimilar materials. wherein adhesion is between leather and other substrates like cotton fibre, nylon, polyester and other synthetics. The use of adhesives in such instances require careful selection and application depending on the end use of the leather product. The present overview discusses at length, the various aspects of usage of adhesives in leather industry keeping; in view the perspectives for the changing needs that are emerging in the third millenium. Description of adhesives widely in use and the improvements required to meet the ecological aspects and online production are discussed in terms of their formulations and physical properties, cure and surface preparations.

Erol Sancaktar; Dept. of Polymer Engineering, University of Akron, Akron, OH 44325-0301

Recent Examples for the Application of Excimer Laser Methods in the Field of Adhesion

The first example involves the use of excimer laser in preparing metal adherend surfaces for adhesion. We used a nonchemical process, which involved the exposure of metal substrate surfaces to pulsed excimer laser radiation at 248 nm wavelength (KrF) to form superior bonding morphology on aluminum, titanium and copper substrates. This process provides safe and efficient alternative to the existing surface etching/modification techniques based on potentially volatile and hazardous chemical organic compounds including harsh acids and chromates. In addition, no post-treatment priming appears to be necessary to maintain the enhanced adhesion strength. For ablation purposes, the high-energy laser pulses are directed on the substrate surface in predetermined geometric patterns to create a surface morphology by melting and rapidly resolidifying the metallic substrate. During cure of substrates treated in this fashion, the polymer adhesive interlocks with the surface topography (projections and ridges) produced by laser irradiation and provides higher strength bonds due to increased mechanical interlocking and chemical bonding. Experiments with single lap specimens comprising aluminum substrates bonded with epoxy resin revealed about 70% improvement in joint deformability, as well as 24% improvement in joint strength, when laser treated, in comparison to the untreated specimens. The improvement in joint strength was 15% when compared with Chromic Acid Anodized (CAA) samples.

The second example involves the application of laser irradiation for optimized welding of polypropylene (PP) using the ultrasonic method. The methods considered for comparison purposes included the following: Improving the joint design by joint interface orientation; Modification of surface polarity by grafting monomers onto polypropylene backbone (PP-g- MA); Thermal and chemical surface pretreatment. Excimer laser ablation surface treatment increases the weld strength 200% for PP and 65% for PP-g-MA in comparison to the untreated material. Irradiation leads to the degradation of the polymer by the disruption of its linear structure. As a result, oxygen in air can react with the radical ends to produce oxidation products, increasing the surface polarity. Furthermore, subsequent to laser irradiation, the required melt flow velocity, Vm, is attained by the molten PP, which is necessary to obtain acceptable strength in the joint plane.

Erol Sancaktar; Dept. of Polymer Engineering, University of Akron, Akron, OH 44325-0301

Mechanics of the Surface Topography Effects in Adhesion

The adhesive joint is traditionally studied with the assumption that it is composed of three entities, namely, the adhesive, the adherend, and the interphase. When not in composite form, the first two entities are usually less complex then the interphase, as we can easily apply the classical formulations of continuum mechanics to describe their mechanical behavior. The interphase, which exists between the adhesive and the adherend has properties different from those of the bulk adhesive, or the adherend because of the action of the mechanical and chemical adhesion processes, adherend surface treatment, and surface topography. In most engineering joints the adherend surfaces have distinct topographies, which result in a collection of miniature joints in micron, and even nano scale when bonded adhesively. If the interphase is not considered as a discrete collection of individual chemical bonds, the methods of continuum mechanics can still be applied to this collection of miniature joints by assuming continuous, or a combination of continuous/discontinuous interphase zones. Thus, the displacement at the interphase need not be continuous at every location. The analysis of a miniature joint contributing to the overall adhesion in a macro joint can be performed in a fashion similar to that for the macro joint itself, which is usually studied with the employment of the methods of elasticity, viscoelasticity, plasticity, fracture, damage, and/or failure, mechanics. In this paper, some preliminary analysis techniques are presented to help incorporate the effects of the adherend surface topography as a discrete entity in the adhesive joint composite. First, the effects of different surface topographies on the mechanical behavior of the adhesive joint are illustrated. The effects of substrate volume, and stress gradient concepts are illustrated next, by using single straight sections in the form of tapered joints. Examples of multi-stepped double scarf joints with void, and disbond effects are illustrated subsequently. Finally, a new mathematical procedure is presented to utilize the complementary energy method, by minimization, in order to find an approximate analytical solution to the 3-D stress distributions in bonded interfaces of dissimilar materials.

Gon Seo; Faculty of Applied Science, Chonnam National University, Kwangju 500-757, S. Korea

Copper Film as a New Adhesive Between Steel Cord and Rubber Compound

(Abstract not yet available)

Jaykumar (Jay) Shah; Scapa Tapes North America, 746 Gotham Parkway, Carlstadt, NJ 07072

Factors Affecting Performance of Pressure Sensitive Adhesives

Adhesive bonding is most suited to those applications where welding can not be used. A pressure sensitive adhesive is a special class of adhesives. It is permanently tacky and bonds to surfaces with light pressure. There are no chemical or physical reactions involved and it requires no time limit to bond. Pressure Sensitive Chemist has the challenging task of developing adhesive systems that have the right balance of performing properties. The chemist has to consider several factors that can effect the performance in the end use. We will cover the most important factors that require careful considerations while designing the formula.

Ralf Frenzel1, Sylvia Schmidt1, Dieter Pleul1, Michael Thieme2, and Frank Simon1

1) Institute of Polymer Research, Hohe Straße 6, D-01069 Dresden

2) University of Technology Dresden, Institute of Materials Science, D-01062 Dresden

Aluminium Surfaces with Non-Adhesion Properties

Several authors observed that leafs of certain green plants are well-cleaned by rain. The reasons of this phenomenon which has been established by Barthlott and Neinhuis as Lotus-effect are the rough structure of the epidermis and minute hydrophobic wax crystals forming an overlaying microstructure [1].

The self-cleaning effect developed during the evolution process can be an example for the design of metal or polymer surfaces applied as construction elements, facades, warps, reflectors etc. One of the most important and progressive construction material is aluminum. The aim of our work was to find principles to treat coat aluminum surfaces to fit them with ultrahydrophobic and non-soiling properties. First, we carried out different procedures to roughen the aluminum surface. Then, the micro-structured surface was coated by silane molecules which were able to form hydrolysis-stable covalent bonds to the oxidized aluminum surface. Other synthetic routes were the irreversible adsorption of fluorinated polymers, polyelectrolytes or polyelectrolytes/fluorinated surfactants, respectively.

The results of the different procedures were evaluated by measuring the contact angles with water as a test liquid. We found dynamic contact angles of Qa > 150 (advancing contact angle) and a very small hystersis between advancing and receding contact angle. The measured contact angles illustrate clearly the self-cleaning properties of the treated aluminum sheets.

[1] Barthlott, W.; Neinhuis, C. Planta 202 (1997) 1-8

Ralf Frenzel1, Dieter Pleul1, Hans-Jürgen Adler2, and Frank Simon1

1) Institute of Polymer Research, Hohe Straße 6, D-01069 Dresden, GERMANY

2) University of Technology Dresden, Institute of Polymer and Textile Chemistry, D-01062 Dresden, GERMANY

Phosphonic Acids to Functionalize Titania Surfaces. Synthesis and Formation of Ultrathin Surface Films.

In the last few years an enormous number of studies on the formation of self-assembly layers have been published. The investigations have been focussed on the adsorption of thioles onto precious metal surfaces and silanes onto oxidized silicon wafers.

The use of n-alkyl phosphonic acids opens a novel route to build up molecular thin films onto inorganic metal oxide surfaces. Especially, substrate materials showing distinct Brønsted-amphoteric properties, like titania and alumina, seem well suited for this surface modification procedure. In addition, to the established thioles and silanes, also the synthetic potential of n-alkyl phosphonic acids allows the introduction of a second functional group in w-position. This second functionality offers a wide range of possibilities to control the surface properties and reactivity of the coated metal oxides.

As model system we used the 12-bromododecane phosphonic acid. It can be obtained by the one-side reaction of 1,12-dibromododecane with triethylphosphite [1]. Some substitution reactions seem appropriate to introduce amino, mercapto and thiosulfate functionalities. The adsorption behaviour of the differently functionalized n-alkyl phosphonic acids is strongly influenced by the character of the second functional group. While the bromo, mercapto and non-functionalized dodecane phosphonic acids adsorb onto titania, the sodium salt of the 12-thiosulfato dodecane phosphonic acid does not undergo any adsorption.

The structure of the ultra thin films were characterized by means of angle-resolved X-ray photoelectron spectroscopy (ARXPS). The variation of the electron take-off angle influences the observed intensities of key elements in the substrate and the adsorbed film, respectively. The data were modelled to calculate film thickness, homogeneity and the molecular orientation in the adsorbed films.

[1] Mäge, I.; Jähne, E.; Henke, A.; Adler, H.J.P.; Bram, C.; Jung, C.; Stratmann, M.: Progress in Organic Coatings, 34 (1998) 1-12

James S. Tonge, Glenn V. Gordon, Michael S. Owen and Michael J. Owen; Dow Corning Corporation, 2200 W. Saltzburg Road, Auburn, MI 48611

Pressure-sensitive Adhesives: Factors Controling the Peel Forces from Silicone Release Liners

Understanding the contributions to peel force pressure-sensitive adhesives (PSA) usually centers on the constituents of the organic adhesive and the nature of the surgace to which it is to be applied. The surfaces studied are generally rigid, high surface energy materials - such as metals, minerals, papers and plastics - and not the flexible, low surface energy silicone release coatings. The adhesives are normally formed on or against laminate constructions. In this study, we will outline the effects of silicone release coating elements on the magnitude of release forces against commercial organic PSA's. The nature of polymer, cross-linker and release modifier on the viscoelastic properties of the silicone release coating will be highlighted.

Lawrence Crane, Afranio Torres and Erin Yaeger; Loctite Corporation, 1001 Trout Brook Crossing, Rocky Hill, Ct 06067

R. Wayne Johnson, Ph.D.; Laboratory for Advance Electronic Packaging, Auburn University

Reworkable Underfills Development, Processing and Reliability

As leaded surface mount devices are replaced by various area array packages such as flipchip, chip scale packages and ball grid arrays, new challenges have arisen in providing the desired package reliability. This challenge includes the stress on the solder ball joints as found in flip chips and the various mechanical stress the CSP and BGA devices are subjected to. The solution to this problem has traditionally been by utilizing underfills to provide the requisite reliability. The use of standard, snap cure or fluxing underfills means the loss of reworkability, such as provided by standard surface mount components. This paper will describe the process of developing, processing and reliability of new reworkable underfills. The paper will focus on recently developed reliability data for CSP's as well as flipchip devices. The applicability of the material in the development of a wafer applied reworkable fluxing underfill will also be addressed.

Naim Akmal1 and Arthur M. Usmani2

1) Union Carbide Technical Center, South Charleston, WV 25303

2) ALTFC USA, Indianapolis, IN 46250

High Temperature Structural Adhesive Polymers

Adhesive bonded joints are much lighter than bolted joints. Yet, aircraft construction utilizes riveting thus contributing significantly to the weight problem. In aircraft, missiles and satellites, structural weight determines operational capabilities e.g., speed, range, and capacity for weapon weight. Furthermore in stealth application, use of structural adhesives instead of bolted joints will contribute toward evading radar detection. The stealth structures require high temperature adhesives. Such adhesives have not seen much research and development and this places a constraint to successfully develop lightweight stealth airframe and engine components.

Bonded joints must be resistant to degradation. We plan to describe non-shrinking high temperature adhesives that lend to minimum internal stress at the bond line in order to reduce dependency on bonded joints, These include easily processable high temperature adhesive polymers e.g., bispherlol fluorenone/bisphenol A polyesters and bisphenol fluorenone/phenolphthaleinlbisphenol A polyesters. Additionally, we have synthesized an acetylene-terminated fluorenone that is useful to cross-link the above-developed thermoplastics.