THE EFFECT OF FIBRILATION ON THE TACK OF PRESSURE-SENSITIVE ADHESIVES

The formation and growth of fibrils during debonding seems to be cruci al to the peel strength and the tack of polymers to be used as pressur e- sensitive adhesives. The objective of this work is to study the inf luence of a number of parameters such as contact force and time, surfa ce roughness, temperature, and rate of separation on fibrilation, and to establish relations between the nucleation and growth of fibrils an d the mechanical behaviour as well as the molecular structure of the a dhesives. Measurements of a large number of model polymers lead to the conclusion that the average mass between entanglements, M-e, is an im portant factor governing fibrilation. Polymers with a high M-e above a bout 1 x 10(4) g/mol show fibrilation whilst materials with an entangl ement length below this limit debond by an apparently homogeneous defo rmation with lower-energy dissipation. (C) 1998 Elsevier Science Ltd. All rights reserved.