The Simplest Failure of Adhesion

Consider the simple melting failure of an adhesive joint as shown in Fig. 7.3. The joint was made by taking a plate of smooth glass, placing a large drop of water upon it, then laying a strip of polyethylene polymer onto the surface of the 

The polythene adhered to the ice below the fieezing point, giving a peeling force of abont 100 mN for a strip width of 10 nun. However, above the melting point, the polymer was released from the watCT easily with httle resistance, about 1 mN. This idea, that a liquid can be frozen onto a solid surface to produce a useful adhesive bonding, is one of the most powerful in adhesion technology it is the thermoplastic adhesive method. 

This process of freezing and melting the joint was quite reversible. It was obvious that mechanical forces did not play any part in destroying the adhesion between the pieces as the joint was melted. Clearly, therefore, mechanical stresses are not the most fundamental cause of adhesion failure in this instance. Adhesive joints fail when the molecular bonding is reduced by melting. 

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