Effects of heat and moisture on characteristics, tensile properties of RFL‐coated rayon cords, and their adhesion with NR/SBR matrix

ABSTRACT The objective of this study was to evaluate the effects of heat and moisture on the characteristics and tensile properties of resorcinol‐formaldehyde‐latex (RFL)‐coated rayon cords and their adhesion to the natural rubber (NR)/styrene‐butadiene rubber (SBR) matrix. The water absorption ratio, shrinking percentage, breaking force, and elongation at break of the cords, which were treated under various temperature‐humidity conditions, were tested, and an attenuated total reflection (ATR)‐Fourier transform infrared (FTIR) spectroscopy was used to investigate the chemical changes of the outer RFL layer. The static adhesion was investigated by an H pull‐out test, and the evolution of the adhesive properties of the RFL‐coated rayon cord/rubber matrix was tracked by an elastomer testing system. A scanning electron microscope (SEM) was employed to observe the interfacial fracture caused by both H pull out and fatigue. The results of this investigation show that the moisture absorption significantly affects the characteristics and the mechanical properties of rayon cords. The chemical state of the RFL layer and the static adhesion of the cord/rubber matrix were not obviously affected, but the interfacial fatigue life was extended due to the decrease of the load in the second of three fatigue stages, which was caused by a reduction in the modulus of the rayon cords. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45559.