Nano silica Modified nano silica Sodium isopropyl xanthate Modified nano silica NR chains Vulcanization More chain entanglements between NR chains and modified nanosilica Highlights Sodium isopropyl xanthate (SIPX) is an efficient accelerator for silica modification. SIPX-bound nanosilica improves cure time of natural rubber (NR) compounds. Improved silica -rubber interaction is achieved by SIPX modification. Thermal aging properties of NR composites are improved by SIPX-NS addition.