Influence of polymeric polarity on the interface of nanocomposites

A polar polymer and a non-polar polymer are selected as polymeric matrix. Nano-TiO₂ is selected as filler and incorporated with such two polymers to construct nanocomposites, respectively. Their thermal behaviors are tested by differential scanning calorimetry. Meanwhile, their dielectric responses and ac electrical strengths are measured. Results indicate that T_g of epoxy nanocomposites is lower than that of neat epoxy resin due to the existence of nanoparticles. However, thermal behavior has no change in LDPE nanocomposites. The dielectric responses also indicate a great deal of difference between the both nanocomposites. However, ac electrical strength first increases then decreases with increasing nanoparticles loading for both kinds of nanocomposites. From the results, it seems that there is a weak relationship between T_g and electrical strength. The polarity of polymer may influence the bond strength between nanoparticles and polymeric matrix. This bond strength affects the arrangement and the mobility of polymeric molecule chain at the interface, which may cause the changes of T_g.