Sol-gel synthesis and morphology, thermal and optical properties of epoxidized natural rubber/zirconia hybrid films

Sol-gel technique was employed to synthesize epoxidized natural rubber/zirconia hybrid films by varying the addition of zirconium(IV)-n-propoxide in the range from 10 to 50 wt.% during the synthesis process. The prepared films were characterized using Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), field emission scanning electron microscopy (FESEM), thermogravemetric analysis (TGA), differential scanning calorimetry (DSC) and refractive index measurements. The possible interaction between zirconia and epoxidized natural rubber (ENR-50) was revealed by both FTIR and UV–vis measurements. The prepared hybrid samples exhibited very good optical transparency. Hybrid films obtained with 30 wt.% zirconium(IV)-n-propoxide addition revealed that the zirconia nanoparticles are uniformly and homogeneously distributed to the ENR-50 matrix with the particle size in the range from 50 to 70 nm. The thermal stability and glass transition temperature (Tg) of the hybrid materials could be increased by the addition of zirconia. The refractive indices of the hybrid materials significantly improved with an increase of zirconia addition.