*2.2.5. Advanced rheometric expansion system and capillary rheometer*

Controlled strain rheological measurements were carried out using an advanced rheometric expansion system (ARES) (TA instruments, USA) with a 200 g-cm transducer within the resolution limit of 0.02 g-cm. 50 mm cone and plate fixtures with nominal cone angle 0.04 rad and nominal gap 0.0508 mm, as well as 50 mm parallel plate fixtures were used for TLCP and its nanocomposite reported here. All measurements were performed at 185 C in N2 atmosphere, where TLCP had been shown to exhibit stable rheological properties under the nematic phase. Care was taken to ensure a controlled thermomechanical history as follows: the rheometer was heated to the testing temperature and allowed to reach equilibrium. Fresh samples, dried in a vacuum oven for 2 days at 120 oC, were loaded in the preheated rheometer, heated up to 185 oC then held for 10 minutes. Decreased gap to the testing gap and kept isotherm for 30 minutes to reach thermal and deformation equilibrium before measurements were started. The experiments were repeated no less than three times to check reproducibility. In each case, a fresh sample was used. For all tests reported here on HMMPE blends, 25 mm parallel plate fixtures were used. All measurements were performed at 190 C with a 2000 g-cm transducer within the

resolution limit of 0.2 g-cm and a 200 g-cm transducer within the resolution limit of 0.02 gcm. Before testing, equipment was preheated and equilibrated at the test temperature for at least 30 minutes [22].

Micro-Rheological Study on Fully Exfoliated Organoclay Modified Thermotropic Liquid Crystalline Polymer and Its Viscosity Reduction Effect on High Molecular Mass Polyethylene 281

further examined using TEM. Typical TEM photographs for the TC3 white nanocomposite are shown in Figure 2. The dark plates, 15-25 nm in length, are the organoclays with surfaces paralleling the observed plane. The organoclays were fully exfoliated and well dispersed in

**Figure 1.** WAXRD patterns of organoclay, TLCP and TC3 white at room temperature.

IR spectroscopy is very sensitive to polymer microstructure and has been widely used in the investigation of hydrogen bonding, macromolecular orientation and crystallinity in polymer materials. FTIR with liquid cell was used with chloroform as background. Figure 3 shows the FTIR spectra for chloroform solutions with TLCP and TC3 white under ultrasonic irradiation at room temperature. It can be seen that the peak at the wavenumber of 1060 cm-1 in TLCP shifts to the wavenumber of 1045 cm-1 in TC3 white. The absorption peak at 1060 cm-1 is believed to represent *C O* in the TLCP molecules. The peak shift is the result of weak interaction between the positively changed N+ ion in the surfactant 2M2HT residing on the surface of the organoclay Closite 20A with *C O*

the TLCP matrix without any agglomeration.

**Figure 2.** TC3 white TEM micrographs.

group in the TLCP molecules.

**3.2. Molecular interactions in nanocomposite** 

The rheological behaviors of the HMMPE blends were also characterized by a capillary rheometer (CR) (Göttfert Rheograph 2003A, Germany) at 190 oC and 230 oC. Here, the controlled piston speed mode was used with the round hole capillary dies (nominal L/D ratio equal to 30/1 and die entrance angle 180°). The real die diameters used here were recalibrated before use (Calibrated dies diameters D = 0.924 mm and 0.542 mm for the nominal D = 1.0 and 0.7 mm dies).

#### *2.2.6. Scanning electron microscopy & transmission electron microscopy*

The TC3 white film embedded in epoxy was ultra-microtomed with glass knives on an ultracut microtome (Leica ultracut-R ultramicrotomed, Germany) at room temperature to give sections with a nominal thickness of 75 nm. Transmission electron microscopy (TEM) images were obtained with a transmission electron microscope at 200 kV (JEOL 2010, Japan).

The morphology of the extrudates generated during the capillary rheometric experiment was examined by high resolution scanning electron microscopy (SEM) (JEOL 6700F, Japan) with the acceleration voltage 5 kv. All samples were sputter-coated with a ~200 *A* layer of gold to minimize charging. The samples were quenched by compressed air from a hose placed near the die exit, providing a cooling ring. This 'froze' the structure of the TLCP droplets or fibrils before they could relax completely. Micrographs of the surfaces of these samples were taken after etching with a 10 wt% aqueous sodium hydroxide solution at 75 oC for 30 minutes.

The extrudate embedded in epoxy was ultra-microtomed with glass knives on an ultracut microtome at room temperature to produce sections with a nominal thickness of 100 nm. The sections were transferred to Cu grids. To enhance the phase contrast, the sections were stained with a ruthenium tetraoxide vapor for 2 hrs. TEM images were obtained with a transmission electron microscope at 200 KV (JEOL 2010, Japan). The 'frozen' extrudate for SEM was used for ultra-microtome. All images were obtained from sample sections microtomed along the flow direction.
