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Crystal Domains (crystal + domain)
Selected AbstractsAn investigation into the morphology and electro-optical properties of 2-hydroxy ethyl methacrylate polymer dispersed liquid crystalsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Huey-Ling Chang Abstract Polymer dispersed liquid crystal (PDLC) films are fabricated using E7 liquid crystals, tetraethylene glycol diacrylate (TeGDA) crosslinking agent, and 0,66.49 mol % 2-hydroxy ethyl methacrylate (HEMA). The effects of different levels of HEMA addition on the microstructure and electro-optical properties of the PDLC samples are examined using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV-Vis spectroscopy, respectively. The results show that the refractive index of the PDLC films is insensitive to the level of HEMA addition. However, an increasing HEMA content improves the degree of phase separation during the polymerization process and increases the size and uniformity of the liquid crystal domain. As a result, the electro-optical properties of the PDLC films are significantly improved as the level of HEMA addition is increased. Overall, the results show that a PDLC comprising 40 wt % E7 liquid crystals, 33.51 mol % TeGDA and 66.49 mol % HEMA has a high contrast ratio (13 : 1) and a low driving voltage (10 V) and is therefore an ideal candidate for a wide variety of intelligent photoelectric applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Ceramic Membranes: Microstructural Engineering of Hydroxyapatite Membranes to Enhance Proton Conductivity (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Mater. The inside cover image showns a side view of a hydroxyapatite membrane with aligned crystal domains synthesized as described by Liu et al. on page 3941. The microstructure of the membrane is engineered to promote proton transport through orientation of the proton conducting paths. These novel structures have significantly higher proton conductivity than traditional hydroxyapatite ceramics and may offer improved performance in intermediate temperature fuel cells. [source] Microstructural Engineering of Hydroxyapatite Membranes to Enhance Proton ConductivityADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Dongxia Liu Abstract A new approach to enhancing proton conductivity of ceramics is demonstrated by aligning proton conductive pathways and eliminating resistive grain boundaries. Hydroxyapatite (HAP) membranes are synthesized by multistage crystallization onto palladium. The synthesis involves three steps: electrochemical deposition of HAP seeds, secondary hydrothermal crystallization onto the seed layer to promote c -axis growth normal to the substrate, and tertiary hydrothermal crystallization to promote a- axis growth to fill the gaps between the aligned crystals. The c -axis alignment with crystal domains spanning the membrane thickness significantly enhances proton conduction since protons are primarily transported along the c -axes of HAP crystals. The novel HAP membranes display proton conductivity almost four orders of magnitude higher than traditional sintered HAP ceramics. The HAP membranes on palladium hydrogen membrane substrates hold promise for use in intermediate-temperature fuel cells, chemical sensors, and other devices. The synthesis approach presented may also be applied to other ion-conducting membrane materials to enhance transport properties. [source] Atomic Force Microscopy Characterization and Interpretation of Thin-Film Poly(butylene adipate) Spherulites with Ring BandsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 15 2008Andreas Frömsdorf Abstract Atomic force microscopy characterization has been conducted to reveal the morphological difference between single-ring bands in poly(butylene adipate) (PBA). Furthermore, morphological features of the ring-less Maltese-cross spherulites are compared to the ring-band spherulites. Periodic changes in height seem to be common for either the ring-band or ring-less (Maltese-cross) crystal domains; however, the steepness in height change is greater for the ring-band crystal, while height change in the ring-less crystal exhibits a terrace-like layer pattern. In the ring-band crystal region, the lamellar stalks, which taper off to pointed needle-like stalks, monotonously protrude out of the layers of softer materials, with no signs of twisting, bending, or turning. In contrast, all lamellae in the ring-less (Maltese-cross) crystal region are uniform platelets arranged like flower petals in a layered pattern. [source] | ||||||||||