Synthesis and characterization of poly1-hexene/silica nanocomposites

SiO2 nano particles, with particle size of 12 nm, were first modified by substituting surface OH groups with O-hexyl moiety. Then, poly1-hexene/modified-SiO2 composites with various nano-SiO2 weight fractions were prepared by three different methods: in situ, solution, and melt methods and designated as PH-SiO2/Insitu, PH-SiO2/Sol and PH-SiO2/Melt, respectively. PH-SiO2/Insitu samples showed highly uniform particle dispersion up to 30 wt. % of silica while in PH-SiO2/Sol and PH-SiO2/Melt samples agglomeration of the silica nanoparticles occurred for filler contents ≥5 wt. % (i.e. 5, 10, 20 and 30 wt%). In the synthesized composites, the storage modulus significantly increased as high as 20.7 times when compared with neat poly1-hexene. Maximum decomposition temperature (Tmax) and char yield at 600 °C increased with increasing silica level. Rheological results showed that Gʹ> Gʺ over the frequency range, illustrating the elastic behavior of the composite samples. In fact, samples showed the characteristic of a non-Newtonian fluid with a strong shear thinning effect in which η* increased with increasing filler weight fraction. From the results, it can be expected that modified silica could replace silica nanoparticles in polyolefin nanocomposite reinforcement.