X-ray scattering and thermal analyses were used to investigate the effects of organically modified layered silicates (OMS) on the paraelectric and ferroelectric phase transitions in poly(vinylidene fluoride-co- trifluoroethylene) [P(VDF-TrFE)]/OMS nanocomposites. Nanocomposites comprising a 75/25 P(VDF-TrFE) random co-polymer with either Nanomer I.30TC or Lucentite STN OMS were prepared with compositions ranging from 2 to 25wt% OMS. Wide-angle X-ray scattering (WAXS) studies show that the silicate gallery spacing increases modestly in the nanocomposites compared to the neat OMS powder, indicating a level of co-polymer intercalation. Thermogravimetric analysis indicates that thermal stability is improved in nanocomposites with higher OMS contents: they have substantial increase in weight remaining, both at 500°C and at 1000°C, compared to that predicted from the behavior of the neat co-polymer and OMS. Differential scanning calorimetry (DSC) and WAXS results show that thermal transitions in the nanocomposites depend on OMS content. Nanocomposites with 2% OMS exhibited a crystal nucleating effect, which results in significant increase in the amount of ferroelectric crystals formed during cooling. For greater OMS additions (10-25%), the amounts of para- and ferroelectric crystals are reduced. The larger OMS additions depress the melt-to-paraelectric transition temperature, while an increase in the paraelectric-to-ferroelectric transition temperature is observed for all compositions. Upon reheating, the ferroelectric phase transition shows significant hysteresis. We conclude that the addition of either Lucentite or Nanomer OMS to 75/25 P(VDF-TrFE) causes an increase in the temperature stability range for the ferroelectric phase.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry