Some Mechanical Properties of Resorcinol-Formaldehyde Latex (RFL) Tire Cord Adhesive

Abstract

Films of resorcinol-formaldehyde latex (RFL) films were made by casting on mercury. The tensile stress-strain curves and tensile and bending moduli were determined for films with different heat-curing conditions and different resin/latex ratios. The heat treatments (240° for 30 min conditions were more severe than in normal hot-dipping and vulcanizing) showed no significant change on the mechanical properties of the films. Changes in the latex/resin ratio produced gradual (not sudden or stepwise) changes in the mechanical properties. The dynamic Young's modulus and loss factor for a standard formulation film from -20°C to +120°C showed small changes, indicating a one-phase system of resin and latex. This evidence was supported by microscopic and electron microscopic evidence. Standard RFL film was shown to be a tough material of adequate extensibility (16%) and a modulus (2.3 × 106 g. cm-2) Intermediate between that of rubber skim stock and nylon tire cord. Its mechanical loss factor shows that it does not contribute unduly to the heat generated in a tire.