The Role of Nano Silica on Rheological Properties and Morphology Development of PP/PBT Blend

An attempt was made to study the effect of the interfacial interaction of nano silica on morphology development of polybutylate terphetalate/polypropylene (PBT/PP) blends. For this purpose Two sets of PBT/PP blend samples with blend ratio of 80/20 and 20/80 and using two type of nano silica differing in surface modification (hydrophilic and hydrophobic) were considered. All of samples were prepared by melt compound using an internal mixer. SEM results shown that in both blend ratios, the hydrophilic nano silica is selectively, located in PBT phase. In PBT/PP (20/80) sample presence of hydrophilic nano silica in PBT droplets was evidenced by increased PBT droplet size due to suppressing of breakup process and in PBT/PP (80/20) similar results observed but with lower intensity due to hindrance effect. However, in nanocomposite samples contained hydrophobic nano silica, the nano silica distributed in matrix, dispersed phase and interface in blend with PBT matrix this decreased the size of PP droplets, This result of decrease in coalescence of droplets and in blend with PP matrix, different result observed on other hand evidenced increasing in the size of particle due to lager capillary number. Comparing the experimental viscoelastic result with the results predict from the emulsion model like (Palierne) was showed that there is good agreement for all virgin blend samples while in sample PBT/PP 80/20 with hydrophobic nano silica shows positive deviation at low frequencies as a result of better interfacial interaction of phases. As observed in DSC results, the presence of hydrophobic nano silica led to descending of crystallinity. The results showed that nano silica didn’t have nucleating effect. The same results in Palierne model observed for blend ratio of 20/80 but in this sample the positive deviation was due to aggregation of nano silica in the matrix. It was confirmed by SEM results.

Keywords:

Nano silica , Polymer blend , Linear viscoelasticity