Effect of modified nano-silica/EVA on flow behavior and wax crystallization of model oils with different wax contents

The nano-hybrid pour-point depressant (PPD) was prepared with organically modified nano-silica covering in EVA. The effects of modified nano-silica/EVA on the flow behavior and wax crystallization of model oils with different wax contents were evaluated. Compared with pure EVA and nano-silica/EVA, modified nano-silica/EVA exhibited a better effect, when doped with 500 ppm, the pour point of the model oil containing 20 wt% wax was reduced from 33°C to 0°C. However, it is noteworthy that pour point cannot accurately reflect the effect of YSiO2/EVA as cold flow improver for a high wax content. The crystal morphology and crystallization behavior of the model oils at low temperature were also observed using polarizing optical microscopy (POM). The results indicated that modified nano-silica/EVA can reduce the size of the wax crystals and disperse the wax crystals by heterogeneous nucleation.