The gel content effect on rheological and physical properties of cured acrylonitrile-butadiene rubber/poly(ethylene-co-vinyl acetate)/organo-montmorillonite nanocomposites

The present work demonstrates the relationship between the tensile and hardness properties, crystalline structure as well as rheological behavior and gel content for the organo-montmorillonite (OMMT) filled poly(ethylene-co-vinyl acetate) (EVA)/acrylonitrile-butadiene rubber (NBR) nanocomposites. The NBR/EVA mixtures containing 5% (wt) OMMT were first provided and then cured with 0-2% (wt) dicumyl peroxide. The results of tensile experiments showed that while the elastic modulus and yield stress linearly increased, strain-at-break linearly decreased with gel content in the range studied. It was also found that the tensile strength and modulus at 100 and 300% strain increased exponentially, however, energy-at-break decreased in the form similar to an inverse S-shaped curve with gel content. The Cole-Cole plots revealed that the relaxation time increased progressively with the increase in gel content. Wide-angle X-ray diffractometry showed that the peak intensity ratio of I-110/I-200 was reduced by the addition of OMMT and increased somewhat with increasing in gel content. In addition, the Casson plot was employed to calculate the yield stress of the materials. The results indicated that the yield stress of the uncured nanocomoposite was higher than that of the simple blend and the value progressively increased with the increase in gel content.

Automated summary

This study investigated the properties of OMMT filled EVA/NBR nanocomposites, finding that an increase in gel content can enhance the elastic modulus and yield stress, while decreasing the strain-at-break. Moreover, the tensile strength and modulus exponentially increased with strain, but the energy-at-break decreased with gel content. Additionally, changes in relaxation time and crystalline peak intensity ratio were observed with increasing gel content in the materials' structure and rheological behavior.