Influence of Epoxide Levels in Epoxidized Natural Rubber (ENR) Molecules on Cure Characteristics, Dynamic Properties and Mechanical Properties of ENR/Montmorillonite Clay Nanocomposites

Abstract

Nanocomposites based on epoxidized natural rubbers (ENRs) with various levels of epoxide groups (i.e., 10, 20, 30, 40 and 50 mol%) and organoclay were prepared by melt mixing process. The organoclay employed in this study was montmorillonite clay modified by octadecylamine (OC-MMT). Cure characteristics, dynamic properties and mechanical properties of ENRs nanocomposites filled with 5 phr of OC-MMT were studied. In all cases, X-ray diffraction results indicated intercalation of ENRs into the silicate interlayer as an increase in the interlayer distance of layered silicates was observed. The maximum torque and torque difference of ENRs nanocomposites increased with increasing levels of epoxide groups in ENRs. Additionally, it was also found that the tan δ value at Tg of the ENR-50 nanocomposite was much lower than those of other types of ENRs nanocomposite. This indicates stronger interaction between ENR-50 and OC-MMT. However, ENR-50 nanocomposite showed the poorest elasticity in term of the tan δ value at the ambient temperature compared to other types of ENRs nanocomposites. A good balance between strength and elasticity was also observed in the ENR-30 nanocomposite. These results are also consistent with the observation that tensile strength and elongation at break of ENR-30 nanocomposite were higher than those of other types of ENRs nanocomposites.