Preparation and characterization of natural rubber/silica nanocomposites using rule of similarity in latex

Rule of similarity and latex compounding techniques were combined for the first time to prepare natural rubber/nanosilica (NR/SiO₂) nanocomposite with core-shell nanosilica-poly (methyl methacrylate) (SiO₂-PMMA) particles and PMMA-modified natural rubber matrix (NR-PMMA). The microstructure of SiO₂ and nanocomposites with different SiO₂ contents was characterized by fourier transform infrared spectroscopy (FTIR); the morphology of nanocomposites was investigated with scanning electron microscopy (SEM); the tensile strength was characterized by tensile testing machine and the thermal stability of composites was studied by thermal gravimetric analysis. Results showed that PMMA chains have successfully grafted onto the surface of SiO₂, and the core-shell SiO₂-PMMA nanoparticles and NR-PMMA latex have been perfectly incorporated. SiO₂-PMMA nanoparticles are evenly distributed over the NR matrix with an average size in the range of 60–100 nm at the low content (SiO₂≤ 3 wt%), while aggregations are apparently observed when 5 wt% SiO₂ is loaded. In addition, NR/SiO₂ composities possess a considerable improvement in ageing resistance compared with the pure NR. The tensile strength of composite increases from 6.99 to 12.72 MPa, reaching the highest value at a 0.5 wt% SiO₂ loading, and then the figure decreases gradually because of the aggregation of SiO₂ nanoparticles. It is anticipated that the reported process is to provide a simple and economic way for preparing NR composites.