Dual modification of natural rubber/halloysite nanotubes composites by silane and maleated natural rubber

As the performance of natural rubber (NR) and halloysite nanotube (HNT) composites is uncertain due to low compatibility between the materials, malleated natural rubber (MNR) is then used as a compatibilizer to encourage filler–rubber compatibility. However, the properties of these composites remain unsatisfactory, and the treatment of HNT requires further improvement. Therefore, this study introduced acid treatment and silane coupling agents to increase the interactions between NR and HNT. Besides, this study also introduced the methods of compounding the rubber composites, either with single-stage or two-stage treatments. The application of a two-stage treatment to acid-treated HNT has given tensile strength a 26.5% improvement. Two-stage treatment enabled better silanization, while acid-treated HNT provided effective silanols for such interactions. The use of silane with acid-treated HNT was found to enhance the tensile strength, modulus, and tear strength of the composites, which was clearly due to better filler–rubber interactions. The Payne effect, which decreased up to 64.03% after applying a two-stage treatment, served as further confirmation of better filler–rrubber interactions. This conclusively proved that modifying both the rubber matrix and HNT enhances the performance of NR/HNT composites.