Glycidyl methacrylate-modified diatomite as reinforcing filler for natural rubber composite

Glycidyl methacrylate (GMA) was grafted onto diatomite (DE) to improve the interfacial bonding between GMA and rubber using “one-step”/“two-step” methods, respectively. The hydroxyl group on DE and the amine group on γ-aminopropyltriethoxysilane (KH550) react with the epoxy group on GMA in a ring-opening reaction during the process. The modified diatomite was characterized and analyzed by using Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence spectrometer (XRF), X-ray diffraction patterns, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Natural rubber/diatomite (NR/DE) composites were also prepared using a wet mixing method and investigated the interfacial interactions between different DE and NR in detail using dynamic mechanical analysis (DMA) and rubber process analyzer (RPA). The result showed the improved mechanical properties of NR/DE composites for both “one-step” and “two-step” methods; however, the “two-step” method is found to be more effective. Compared with the unmodified NR/DE composites, the “two-step” modified NR/DE composites exhibited an increase in 37.8% tensile strength, 25.1% tear strength, 11.7% abrasion resistance, and 24% wet slip resistance, respectively. In addition to these, GMA has minimal effect on the elongation at break retention of the rubber composites after aging. These results showed valuable insights for the further application of diatomite in rubber.

Graphical Abstract