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Swissbonding summit: Maurice Bowtell reports on the innovations and developments unveiled at the Swissbonding Conference in Switzerland.

Article Excerpt
The 18th international Swissbonding technical conference took place from 17-19 May this year at Rapperswil on the Lake of Zurich, again under the leadership of its president Professor Eduardo Schindel-Bidinelli of Swibotec/SWB, Bulach, Switzerland. It covered three sessions addressing the chemistry of adhesives with emphasis on pretreatment, applications, products, testing, recycling and environmental aspects. The meeting was attended by more than 200 delegates from 18 countries clearly with a strong European representation, but there was also a good input from the Far East. Also, the usefulness of the event was underscored by the fact that more than half (52%) of the attendees were end users, followed by producers of additives (30%). In addition, its success owed much to the variety of subject matter in the 32 papers presented.

A good example here was an academic presentation by Dr Walter Federle of the Department of Zoology, University of Wurzburg, Germany, who addressed the wet adhesion and rubber friction in the adhesive pads of insects. He said that many animals possess on their legs adhesive pads, which have undergone evolutionary optimisation enabling them to attach to various substrates and to control adhesive forces during movement.

HAIRY DESIGN

Dr Federle said that theoretical models show that adhesion can be increased by splitting the contact zone into many microscopic elastic subunits, which provides a functional explanation for the widespread 'hairy' design. In many hairy and in all smooth adhesive systems, adhesive contact is achieved by a thin film of liquid secretion between the cuticle and the substrate. By using interference reflection microscopy (IRM), the department assessed the thickness and viscosity of the secretion film in weaver ants. It was found that 'footprint' droplets deposited on glass are hydrophobic and form low contact angles.

In addition, the IRM of insect pads in contact showed that the adhesive liquid is an emulsion consisting of hydrophilic volatile droplets dispersed in a persistent hydrophobic phase. In the study, predictions derived from film thickness...

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