Acrylamide-grafted saponified natural rubber via continuous UV irradiation for silica composites

Abstract

Acrylamide-grafted saponified natural rubber (FSP) was prepared using a continuous UV-induced grafting process. The saponification step reduced nitrogen content and modified the molecular characteristics of natural rubber, providing a suitable substrate for functionalization. Spectroscopic analyses confirmed the presence of acrylamide-derived functional groups on the rubber backbone. The influence of flow rate, lamp-to-sample distance, and monomer concentration on grafting efficiency was systematically investigated to determine optimal continuous processing conditions. When incorporated into silica-filled rubber compounds, FSP exhibited higher bound rubber content and a reduced Payne effect compared to unmodified SPNR, suggesting improved rubber–silica interaction. SEM observations were consistent with these trends. Mechanical properties were maintained or moderately improved, particularly at 10 phr AM. The results indicate that continuous UV grafting provides a controllable approach for enhancing rubber–silica compatibility without compromising mechanical performance.