Materials Science Forum Vols. 663-665

Abstract: The effect of magnetic field on the flow-phase diagram of discotic nematic liquid crystalline polymers (LCPs) is analyzed with the extended Doi theory in which the molecular shape parameter is defined at negative one. The evolution equation for the probability function of the LCP molecules is solved without any closure approximations. The transition among flow-orientation modes, such as tumbling, wagging and aligning defined similar to the rodlike LCPs, are strongly affected by the magnetic fields parallel to the flow direction.

Abstract: Fractal features of branch-like structures grown from isotropic melt of a cholesterol liquid crystal were investigated with differential scanning calorimetry, polarized optical microscope and computer-aided simulation, respectively. With box-counting method, we have calculated the fractal dimension to be about 2.558-2.604 for the branch-like aggregates. Our growth simulation and the calculated value of the fractal dimension suggests that the cluster-cluster aggregation model can be applied to the growing processes of branch-like structures from isotropic melt of a cholesterol liquid crystal.

Abstract: The effect of magnetic field on shear stress of disklike nematic liquid crystalline polymers (LCPs) is analyzed with the extended Doi theory in which the molecular shape parameter is defined at negative one. The evolution equation for the probability function of the LCP molecules is solved without any closure approximations. It can be seen that the shear rate regions of the sign changes of the time-averaged first normal stress differences are completely contrary with those conclusions achieved for the rodlike LCPs.

Abstract: We demonstrated that a lamellar phase of lyotropic liquid crystal formed by liquid dishwash could assemble themselves into crystal droplets when their isotropic phase was slowly changed into lamellar phase on the glass substrate. Characterization by means of polarized optical microscopy showed that a pattern of liquid crystal droplets was developed in the thin films formed by liquid dishwash. Our laser light diffraction experiments confirmed that these liquid crystal droplets could effectively diffract the incident red light from a helium-neon laser. On the basis of the Fraunhofer diffraction equation, we derived for the diameter of liquid crystal droplets. The diameter of liquid crystal droplet is 42.517 m, and almost agreement with the graph of polarized optical microscopy.

Abstract: With effective screen-printing technique, the flat-panel field emission lamp (FPFEL) based on carbon nanotube as cold cathode material was fabricated. The prepared CNT paste was printed on the cathode glass plate to form the field emitter and sealed into the device vacuum room of FPFEL. For improving the display image uniformity, the discrete anode indium tin oxide (ITO) zones method was adopted, and the anode voltage could be applied through the silver anode connecting line for the different anode ITO zones. The anode insulation wall was fabricated to support the anode glass plate, which the deforming of anode glass plate would be avoided. The emission image for the small vacuum-sealed FPFEL with printed carbon nanotube as field emitters was presented. The fully-sealed FPFEL possessed high luminance brightness and better field emission uniformity.

Abstract: A bent-core liquid crystal compound N,N-bis (4-propoxybenzylidene)benzene- 1,3-diamine was synthesized. Phase transition properties of the synthesized compound with the deferent heating rate were characterized with differential scanning calorimetry and polarized optical microscopy. , respectively. Our results demonstrated that the bent-core compound exhibited the completely undivided multi-phases in heating-rate ranges from 1oC/min to 6oC/min while it showed a broad-peak crystal phase in higher heating-rate ranges of 7-10oC/min for the first heating.

Abstract: Carbon nanotube used as cold cathode, the triode FED with staggered gate-electrode layer structure was fabricated with the screen-printing technique and conventional sintering process. Using superior mica plate as gate substrate material, the silver slurry was prepared to form the staggered gate electrode. The insulation layer was also manufactured over the gate substrate surface. The design and fabrication of the staggered gate-electrode layer was described in detail. By means of glass frit, the whole panel structure was vacuum-sealed. With the fabricated staggered gate-electrode layer, the modulation of electron emission from CNT field emitter by the gate voltage was confirmed. The packaged tridoe FED possessed better field emission uniformity, good image display performance and high display image brightness.

Abstract: Polymer dispersed liquid crystal (PDLC) devices were prepared by the method of polymerization induced phase separation. The transmittances and textures of the PDLC devices in OFF state and ON state were characterized by an ultraviolet-visible spectrometer and a polarized optical microscope, respectively. Our results demonstrated that the transmittances of our PDLC devices can be up to 95% when it is in ON state and that the transmittances of our PDLC devices is only about 20% when it is in OFF state.

Abstract: Screen-printing process was adopted to prepare the carbon nanotube cathode. For improving the field emission performance of cold-cathode material, the optimized carbon nanotube cathode fabrication structure was given, and the detailed manufacture process was also described. The photoetched cathode indium-tin-oxide (ITO) stripes including the narrow bar ITO connecting line was fabricated to form the cathode electrodes. The annular silver conducting layer was adopted between the cathode ITO stripes and the carbon nanotube field emitters. The whole display device was packaged by means of glass frit, and vacuum-sealed through the exhaust tube. The fabricated field emission display could display some dot matrix number and characters, which possessed better field emission performance, higher display brightness and good field emission uniformity.

Abstract: Polymer dispersed liquid crystal film was prepared by the method of polymerization induced phase separation. The optical morphologies of the PDLC film were characterized by polarized optical microscope with a hot stage. Our results demonstrated that the morphology of the PDLC film depended on temperature of PDLC system.