A thermotropic liquid crystalline polymer (TLCP), denoted as TLCP(1), was used as a processing aid for high density polyethylene (HDPE). The TLCP was a copolyester of hydroxybenzoic acid, hydroquinone and sebacic acid and was blended with HDPE to give 0.2, 0.5 and 2 wt% TLCP(1) blends. At a temperature of 185°C, when TLCP(1) is in the nematic regime, the processing window for HDPE was increased tenfold from a maximum shear rate of 100 s−1 for pure HDPE to 1170 s−1 for a 2 wt% TLCP(1) blend. There were large viscosity reductions of between 85% and 90% compared with the pure HDPE when the blended material was used at a wall shear stress value of approximately 2.4 × 105 Pa. This viscosity reduction was attributed to the TLCP(1) droplets changing shape from spheres to slender fibrils under shear flows.
We report the fabrication of opal structure using metallo-dielectric silica microspheres. Mono-dispersed silica microspheres were coated with silver using an electrode-less wet-plating technique. Thin slabs of opal were obtained by assembling the silver-coated microspheres between two glass plates using a forced-packing method. The optical properties of the resulting opal structure were studied in the infrared range. Good agreement is obtained with the predictions of a multiple scattering approach, provided that the silver layer is modelled as a silver composite.
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