SEM-EDX analysis and TOF-SIMS 3D imaging of a textile/rubber interface undergoing fatigue loading

Abstract

Unidirectional textile⿿rubber composites must exhibit a strong interface to reach admissible lifetime expectancy. Usually, this is achieved by coating the textile with Resorcinol-Formaldehyde-Latex (RFL). Nevertheless, former SEM observations of our composite revealed microcracks at the RFL/rubber interface. They appeared to propagate through fatigue loading, in correlation with hardening of RFL and interfacial rubber, both highlighted by nanoindentation tests. This mechanical damage was not correlated to chemical structure degradation which limited the development of more reliable interfacial materials⿿ formulations. In this perspective, EDX and ToF-SIMS are used in the present study to characterize RFL coated textile and composite's textile/rubber interface compositions, before and after different numbers of cycles of fatigue loading. Those analyses allow the identification of textile contaminants, potentially responsible for composite's initial interfacial microcracks: inorganic grains, polysiloxanes, fatty acids, latex surfactants and esters contaminants, attributed to diffusion from the RFL layer or from textile sizing. Concerning RFL hardening, four potential mechanisms can be raised: VP-latex complexation with metallic ions coming from rubber formulation, RF post-condensation or disproportion, migration of latex surfactants and thermo-oxidative degradations. This last mechanism seems to be the main one responsible for the hardening of interfacial rubber.