Organoclay/thermotropic liquid crystalline polymer nanocomposites. Part IV: organoclay of comparable size to fully extended TLCP molecules
Organoclay with a size of 100–200 nm was successfully prepared by a combination of wet ball milling and ultrasonication methods without changing its physico-chemical properties. A nanocomposite (TC3 FS) of 3.0 wt% treated organoclay in thermotropic liquid crystalline polymer (TLCP) was prepared. The treated organoclay was of comparable size to the fully extended TLCP molecules and it formed weak interactions with them. The liquid crystallinity of the TLCP was not greatly affected by the treated organoclay at the nematic temperature of the TLCP. Rheological characterization demonstrated that the viscosity of the TC3 FS was less than one order of magnitude higher than that of the TLCP in the linear viscoelastic region, and the steady shear viscosity of the two materials was comparable in steady shear experiments. Thus, TC3 FS is a promising viscosity reduction agent for high molecular mass polyethylene (HMMPE), functioning similarly to TLCP. The 1.0 wt% TC3 FS in HMMPE has more efficient viscosity reduction ability than the 1.0 wt% TLCP in HMMPE, with lower yielding stress and yield-starting shear rate, as well as a narrower yield shear rate region. The viscosity reduction ability of the TLCP was enhanced by the treated organoclay.
KeywordsShear Rate Liquid Crystallinity Polarize Optical Microscopy Linear Viscoelastic Region Viscosity Reduction
Y. H. Tang and P. Gao gratefully acknowledge the Research Grant Council of Hong Kong (Grant number HKUST6256/02) for financial support.