Nanoimaging and spectroscopic analysis of rubber/ZnO interfaces by energy-filtering transmission electron microscopy

Energy-filtering transmission electron microscopy (EFTEM) was employed for investigating interactions between rubber and ZnO particles in the accelerated vulcanization process. Combining elemental mapping and electron energy loss spectroscopy (EELS) by EFTEM enabled the characterization of the interfaces with spatial resolutions of less than 10 nm and with high elemental detection sensitivity. We found that a sulfur- and zinc-rich compound was generated around ZnO particles, and that product was then revealed to be ZnS-generated as a byproduct in the accelerated vulcanization process. Through this study, it is indicated that the accelerated vulcanization with ZnO does not occur uniformly in the rubber matrix; it occurs locally around ZnO particles at a higher reaction rate, implying that the rubber network structure is not uniform on the nanoscale.