post-curing epoxy hot-melts. First investigations of model resins were rather promising. Professor H. Brockmann (Co-author: Dr Barwich, both University of Bielefeld, FRG) continued in this theme with a lecture on the reaction behaviour of hot-curing epoxy adhesives. The chemical behaviour of dicyandiamide (curing agent) and monuron (accelerator) is now understood and can be optimized in technical processes. Professor Vohwinkel (FH Osmabnack, FRG) lectured on cold-curing epoxy resins and their use at higher temperatures. In this context, he presented the influence of formulations, elastifications, additives and recipes on mechanical values.

The section 'Test Techniques' comprised three lectures. Professor Hahn (University of Paderborn) reported on the influence of construction and limitation of manufacturing processes. Dr H.- G. Cordes (Tivoli Werke AG, Hamburg) expressed his thoughts concerning test philosophy of ageing processes. An essential demand was standardization of test methods. Dr Sch~ifer (IFAM, Bremen, FRG) closed the section with a lecture on electronmicroscopical investigations of bondings.

During the first lecture of the section 'Processing', Dr Sauer, RWTH Aachen (Co-author: Dr Reiner, Siebe-Engineering, Neuwied, FRG) presented results of mechanical adhesive preparation and application in context with quality control. He described a procedure for an exact selection and design of suitable mixing systems as well as the determination of the best application parameters. Dipl-Ing E. Cordes (DB AG, Bremen, FRG) discussed the need for the substitution of solvent-based adhesives. For an acceptable solution he asked for teamwork between adhesive producers and users. Then, Dr W. Brockmann (IFAM, Bremen) lectured on the research project 'Fertigungstechnologie Kleben FFK'.

Professor Strassburger (Thyssen AG Duisburg, FRG) began the last section 'New Materials' with a lecture on manufacturing behaviour during the joining of fine sheets of modern steel sheets. Dr Thorbeck (Lufthansa, Hamburg, FRG) gave an account of composite repairs of aeroplanes. He presented the different problems and demands for this repair technique of these modern materials. During the last lecture of the conference, Dr Smernos (SEL AG, Stuttgart, FRG) described new developments for new base materials of boards for the future.

The multiplicity of the presented works made it evident that such a conference needs an international character. Therefore, the FSK-conference 1989 in Bremen gave a very good summary of our actual knowledge in adhesive bonding. For this reason the lectures will be published in a DECHEMA- monograph. This may be ordered from: DECHEMA~ Postfach 97 01 46, 6000 Frankfurt/M 97, FRG).

A Gross

4th Symposium on adhesion

Muehlhausen, GDR, 10 -13 October 1989

The 4th Symposium on 'theoretical and practical aspects in adhesion between condensed phases' took place at Muehlhausen, GDR from the 10 to 13 October 1989.

The Institute of Polymer Chemistry 'Erich Correns' of the Academy of Sciences of the GDR at Teltow- Seehof was again organizer of this event which takes place every two years. Fifty-five participants from England, FRG, GDR, Switzerland, USSR and Western Berlin followed the invitation from Professor C. Bischof and Dr A. Bauer to this now traditional event.

The content of the 20 lectures dealt with basic problems in theoretical concepts of adhesion, its experimental realization and special practical uses. It was not only the lecturers which gave a great deal of interesting facts and information, but other participants with their questions and comments determined the high level of discussion.

The following remarks are intended to give a short overview on the variety of the papers presented.

The opening lecture was given by W. Brockmann (Bremen, FRG) on 'Adhesion research at the end of scientific possibilities or at a new beginning'. Actual theoretical and methodical restrictions in the resolution of interface structures were named. For the successful case the use of microscopical models and their correlation with real joint properties would give a new beginning in adhesion science.

K.W. Allen (London, England) spoke on 'Some aspects of the fundamental theories of adhesion'. Diffusion processes, electrostatic interactions, mechanical interlocking and adsorption (or specific) interactions were mentioned as explanations of the main phenomena of adhesion. Some inferences were drawn about their relative significance in different circumstances and about their simultaneous action to reinforce each other.

Results on polymer adsorption on metallic surfaces obtained by mass-and/or electron spectroscopy were presented by O.F. Posdnyakov and S.Ch. Tabarov (Leningrad, USSR). Correlations were discussed between adsorption values and adhesion strength.

Problems of application of bonding technologies in electronics were the topic of the lecture by E.H. Schindel-Bidinelli (Rorbas, Switzerland). Especially, problems of electrical and bondline corrosion in joints caused by using electrically conductive adhesives were pointed out.

Adsorption of polybutadiene epoxides on inorganic interfaces as a pre-reaction step was reported by Brigitte Heublein (Jena, GDR). Mechanisms were

INT.J.ADHESION AND ADHESIVES APRIL 1990 109

proposed for reactions following this step and bonding states in the interface were discussed.

J. Gaehde (Berlin, GDR) had investigated the action of chromium dioxide surfaces in a polyurethane matrix. Dependent on polyurethane structure and storage temperature, changes in the polymer structure were also obtained due to existing CrOlI) in this system.

XPS-investigations of PMMA-films on ambient aluminium surfaces were carried out by W. Possart (Teltow, GDR) with the aim of obtaining results on special interactions on such interfaces. The role of the underlying physical model of spectra-origin and of its mathematical description were emphasized.

Monika Bauer (Teltow, GDR) presented results on reaction mechanisms and by this means formed structural elements of cyanurate polymers. Possibilities and limitations in the application of such polymers as adhesives, dependent upon its properties were investigated. The possibility was pointed out for using such cyanurates as models of reactive systems for investigating the type and strength of adhesion.

The influence of surfactants on the structure of epoxide and polyurethane systems was reported by R.A. Veselovsky (Kiev, USSR). The importance of this influence for adhesion processes was shown by experimental results.

The chemical modification of polyethylene terephthalate in order to modify its glass transition temperature and crystallization behaviour was the topic of the lecture of E. Schaaf (Teltow, GDR). Such modification makes it possible to vary the application properties of these polyesters for the necessities of solvent lacquers or hot melts.

J.A. Mulin (Leningrad, USSR) presented an extensive and specified system of semi-empirical equations for calculating the adhesion strength of polymers. Main constituents of these equations were well-known or experimentally determined polymer properties. All equations were fitted by adjustable parameters.

Investigations on charge and heat transport through adhesive joints were the subject of L, Dorn's ('I'Ll West Berlin) lecture. Measuring methods were presented and influences of technological parameters of joining determined in this way were discussed.

Possibilities of electrochemical impedance spectroscopy for characterizing the real metal surfaces were demonstrated by G. Reinhardt (Dresden, GDR). Such characteristics are essential for interactions between metals and polymers.

Results on the influence of plasma treatment on the strength of polymer/metal joints were the content of J. Ffiedrich's (Berlin, GDR) lecture. Appearing redox

reactions on joint-interface mainly due to the plasma treatment lead to improved adhesion but also decreases mechanical strength of the polymer by damaging the polymer structure.

The influence of roughness on contact angle measurement was analysed by R.-D, Schulze (Teltow. GDR) by an example of a tow molecular liquid on a polymer surface. A connection between empirical and theoretical description of this phenomenon was found, the experimental application was demonstrated and interpretation limits of roughness from contact angle measurements were pointed out.

Problems in reliability of solder connections between leadless ceramic chip carriers and thick-layer substrates were demonstrated by J~ Albrecht (Berlin, GDR). Existing leaching effects and formation of intermetallic phases in joint zones were held responsible for failures of solder connections.

Questions of adhesive technology in microelectronics as applied to adhesion research were presented by C. Bischof (Teltow, GDR). By means of requirements of microelectronics on bonding technology on main adhesive classes and its purposeful modification as well by means of application examples the necessity was pointed out for deeper insight in molecular interactions between interfaces by more interdisciplinarity in basic research.

Influences on the properties of circuit boards based on copper foil coated phenol-formaldehyde-prepregs (FR-2) dependent upon adhesive systems and the technological conditions of coating were shown by D. Maeusebach (Bernau, GDR).

In order to ensure adhesion of polyethylene foils on steel Sabine Friedrich (Potsdam, GDR) and her colleagues oxidized the steel surface. Under special conditions the polyethylene foil can be removed together with the oxide layer from the metal. This joint proved moisture-sensitive with a characteristic moisture-conductivity dependence.

The great interest of colleagues of different scientific affiliations in problems of adhesion was obvious also at this symposium. Therefore, the desire for a regular exchange of experiences and information in this field and in interdisciplinary reflection especially, exists and increases. Many participants agreed with the suggestions of the organizers to organize the 5th meeting in 1991 in a similar manner.

J. Schneider

The complete lectures are to be edited as a special booklet, available from: Dr A. Bauer, Institute of Polymer-Chemistry 'Erich Correns: Kantstrasse 55, DDR- 1530 Teltow-Seeh of. in June 1990.

110 INT.J.ADHESION AND ADHESIVES APRIL 1990