ROLE OF ADHESION IN VISCOELASTIC PROPERTIES OF RUBBER-TIRE CORD COMPOSITES

In the reported experiments, dynamic mechanical measurements have been carried out on samples of rubber and PET cord-rubber composites, with and without adhesive, as a function of strain amplitude, temperature, pretension, angle of strain application and time of cycling. The results show that mechanical loss and dynamic modulus depend on these variables as well as the presence and type of adhesive at the cord-rubber interface. It is concluded that adhesion plays a significant role in the viscoelastic properties of a composite and it is an important factor along with the properties of components in the analysis of tire performance in terms of composite properties. This study clearly shows that the maximum adhesion may not be the optimum adhesion in tire technology. The most relevant question, i. e. , the determination of the optimum level of adhesion for a specific tire, however, remains unanswered. The viscoelastic properties of the composites decrease with time of cycling but the rate of decrease depends upon the level of adhesion in the starting material. This result could be important in the development of a more realistic dynamic adhesion test.