ADHESION BEHAVIOR OF NYLON TIRE CORD/ADHESIVE-RUBBER SYSTEMS

In static and dynamic adhesion tests, the behavior of nylon tire cord/resorcinol‐formaldehyde–latex (RFL) adhesive/rubber systems was shown to be strongly influenced by the dipping and curing conditions, cord size, and the thickness of rubber layer adjacent to cords. The nature and extent of these effects were different in three types of adhesion tests which differed in stress concentrations they induced at the cord–rubber interface. The influence of stress concentration due to increased cord size was clearly seen in dynamic adhesion tests where the peel strengths of two‐ply cord/rubber samples were measured after flexing them under tension over a pulley for predetermined periods at 230°F. In these tests, the adhesion of samples with large cords weakened more rapidly than that of small cords. The static adhesion level attained with nylons 6 and 66 and other polyamide fibers was strongly dependent on the conditions (time, temperature) under which the RFL adhesive was applied and cured. At any given exposure, adhesion initially increased rapidly with the RFL curing temperature and attained a maximum above a temperature which is characteristic of the polyamide. For nylon 66, optimum adhesion was attained with different combinations of RFL curing temperatures (390–460°F) and times (20–120 sec). Finally the adhesion of nylons 6 and 66 is discussed from thermodynamic considerations based on entropy change. Copyright © 1969 John Wiley & Sons, Inc.