**2. Experimental**

276 Viscoelasticity – From Theory to Biological Applications

many researchers [11-14].

characterized at 185 oC when the TLCP was in the nematic regime; substantial viscosity

It is worth noting that even in early studies of polymer blends containing TLCP, researchers had already attempted to introduce inorganic reinforcements into such blend systems [4]. The addition of inorganic fillers not only enhanced the mechanical properties of the blends but also reduced the anisotropy of the resulting materials [5]. Rheological characterization revealed that TLCP could reduce the melt viscosity of glass-filled thermoplastics [6]. Much work has been published on TLCP systems containing different inorganic solid reinforcements, such as glass fibres [7], carbon black [8], whiskers [9] and silica [10]. Most of the studies have used high inorganic solid reinforcement content and have focused on the

Layered silicates have long been used as fillers in polymeric systems to improve mechanical, thermal and other properties in the resulting polymer composites. In layered silicate itself, the local interaction between layers causing the presence of domains similar to those found in studies of liquid crystalline and ordered block copolymer systems have been analyzed by

It seems that intercalation or exfoliation of layered silicates in polymers should induce nanocomposites to exhibit similar rheological behaviour to that found in the nematic state structures in LCPs. Nanocomposites based on thermotropic liquid crystalline polymer and organically modified layered silicate have been studied by several groups with different foci. Zhang et al. [15] synthesized a series of liquid-crystalline copolyester/organically modified montmorillonite nanocomposites by intercalation polycondensation with different surfactant modified clay in LCP. X-ray diffraction and transmission electron microscope studies indicated that, after ion exchange with suitable surfactants, clay formed delaminated morphology and was well dispersed in LCP. Chang et al. [16] reported nanocomposites of TLCP with an alkoxy side-group and an organoclay (Closite 25 A) prepared by the melting intercalation method above the melt transition temperature of TLCP, with liquid crystallinity of the hybrids being lost when the organoclay content exceeded 6.0 %. Vaia et al. [17] directly annealed a powder mixture of TLCP and clay within the nematic region of TLCP under high hydraulic pressure. Reversible intercalation formed, with a loss of liquid crystallinity which was attributed to the confinement of LCP chains on the clay pseudo-2D geometry. An extensive study of a series of nanocomposites with a segmented main-chain liquid crystalline polymer having a pendent pyridyl group (PyHQ12) or a pendent phenylsulfonyl group (PSHQ12) and commercial Closite 20 A or 30B clays by examining rheological and other properties was reported by Huang and Han [18, 19] to demonstrate whether functionality of TLCP was essential to obtain highly dispersed clay in nanocomposites with TLCP as matrix. Only intercalated morphology formed when the nanocomposites were based on a TLCP without functionality. The formation of hydrogen bonds caused a very high degree of dispersion but a considerable loss in the degree of liquid crystallinity in a PyHQ12/30B nanocomposite. From the above studies, it can be seen that functionality in TLCP is necessary to obtain highly dispersed nanocomposites, but at the same time, there is the possibility of loss some degree of liquid crystallinity in the TLCP.

reductions of between 85% and 90% compared with pure HDPE were observed.

balance between the mechanical properties and processability of such blends.
