The performance of rubber composite relies on the compatibility between rubber and filler. This is specifically of concern when preparing composites with very different polarities of the rubber matrix and the filler. However, a suitable compatibilizer can mediate the interactions. In this study, composites of natural rubber (NR) with halloysite nanotubes (HNT) were prepared with maleated natural rubber (MNR) and modified palm stearin (MPS) as dual compatibilizers. The MPS dose ranged within 0.5–1.5 phr, while the MNR dose was fixed at 10 phr in all formulations. It was found that the mixed MNR/MPS significantly enhanced modulus, tensile strength, and tear strength of the composites. The improvements were mainly due to improved rubber-HNT interactions arising from hydrogen bonds formed in the presence of these two compatibilizers. This was clearly verified by observing the Payne effect. Apart from that, the MPS also acted as a plasticizer to provide improved dispersion of HNT. It was clearly demonstrated that MNR and MPS as dual compatibilizers improved rubber-HNT interactions and reduced filler-filler interactions, which then improved tensile and tear strengths, as well as dynamical properties. Therefore, the mix of MNR and MPS had a great potential to compatibilize non-polar rubber with HNT filler.

In this study, maleic anhydride (MA) grafted natural rubber (NR), known as maleated natural rubber (MNR), was melt-prepared with the MA content varied within 1–8 phr. MNR was used as the main matrix, with Halloysite Nanotubes (HNT) as a filler, in order to obtain composites with improved performance. The compounds were investigated for their filler–filler interactions by considering their Payne effect. On increasing the MA content, scorch and cure times increased along with maximum torque and torque difference. The MNR with 4 phr of MA exhibited the least filler–filler interactions, as indicated by the retention of the storage modulus after applying a large strain to the filled compound. This MNR compound also provided the highest tensile strength among the cases tested. It is interesting to highlight that MNR, with an appropriate MA content, reduces filler–filler interactions, and, thereby, enhances the HNT filler dispersion, as verified by SEM images, leading to improved mechanical and dynamical properties.