Morphology Development and Melt Viscoelastic Properties of PTT/PET/TLCP Ternary Blend

Abstract

The morphology development and melt linear viscoelastic properties of PTT/PET/TLCP ternary blends were studied and results were compared with PET/TLCP and PTT/TLCP binary blends. The blend samples were prepared by melt mixing of the blends component both in an internal mixture and a modular twin screw extruder. The morphological studies were perform on cryogenically fracture samples using SEM. The meltstate linear viscoelastic properties of samples were studied by using a rheometric mechanical spectrometer (RMS). Differential scanning calorimeter was employed to examine the crystallinety of the sample. The SEM results showed a matrix disperses type morphology in which thermotropic liquid crystalline polymers (TLCP) phase was uniformly dispersed in polymer matrix. The average diameter of the TLCP particle in PET/ TLCP blend was found to be comparable with that in ternary blends but smaller compared to PTT/TLCP blend. For all the blends, the average TLCP diameter was smaller for the samples prepared by extruder compared to those produced by internal mixer. These results suggested lower compatibility between PTT and TLCP phase compared to that between PET and TLCP. The melt viscoelastic properties of the PTT/PET binary blend seemed to obey the additive rule suggesting that the PET and PTT melts are miscible. It was also shown that the viscoelastic properties of ternary blends was predominately controlled by matrix components and indicating that TLCP phase remains as dispersed droplets in the matrix. The results obtained of DSC showed a single crystallization temperature peak (Tc ≈ 155 ºC) for PET/PTT binary and PET/PTT/TLCP ternary blends; the results which could support the SEM and viscoelastic results.