Preparation and properties of nanocomposites based on different polarities of nitrile-butadiene rubber with clay

Nanocomposites were prepared with different grades of nitrile-butadiene rubber (NBR) [with nitrile (CN) contents of 26, 35, and 42%] with organoclay (OC) by a melt-compounding process. The rubber/clay nanocomposites were examined by transmission electron microscopy (TEM) and X-ray diffraction (XRD). An increase in the polarity of NBR affected the XRD results significantly. The dispersion level of the nanofiller in the nanocomposites was determined by a function of the polarity of the rubber, the structure of the clay, and their mutual interaction. The intercalated structure and unintercalated structure coexisted in the lower polar of NBR. In addition, a relatively uniformly dispersed state corresponded to a more intercalated structure, which existed in the higher polar of NBR matrix. Furthermore, high-pressure vulcanization changed the extent of intercalation. The mechanical properties and gas barrier properties were studied for all of the compositions. As a result, an improvement in the mechanical properties was observed along with the higher polarity of NBR. This improvement was attributed to a strong interaction of hydrogen bonding between the CN of NBR and the OH of the clay. Changes in the gas barrier properties, together with changes in the polarity of the rubbers, were explained with the help of the XRD and TEM results. The higher the CN content of the rubber was, the more easily the OC approached to the nanoscale, and the higher the gas barrier properties were.