Effect of disaggregation and activation of sepiolite on interfacial interaction and mechanical properties of natural rubber/sepiolite composites prepared by latex compounding method

The demand for environmentally friendly and non-petroleum based natural rubber products is on the rise. Sepiolite, a one-dimensional clay mineral, has been found to be a suitable reinforcement for natural rubber through latex compounding. However, the aggregation of fibers and minerals may impact the overall properties of natural rubber composites. To overcome this challenge, the study utilized ultrasonic disaggregation and oxalic acid activation to prepare stable sepiolite suspensions with varying specific surface areas and surface activities. These suspensions were then mixed with natural rubber latex to prepare NR/sepiolite composites. The results showed that the dispersibility and bonding ability of sepiolite with natural rubber were improved due to the increased specific surface area and surface activity, resulting in more bonding sites. The mechanical properties of the composites were also found to be improved, with a significant increase in tear strength (from 61.9 to 67.6 N.-1) and tensile strength (from 23.0 to 29.5 MPa). This research lays a strong foundation for the utilization of sepiolite in rubber materials.