Home About us Contact
|
Home About us Contact | ||
|
|
||
Fabrication Procedure (fabrication + procedure)
Selected AbstractsMatrimid®/MgO mixed matrix membranes for pervaporationAICHE JOURNAL, Issue 7 2007Lan Ying Jiang Abstract For the first time, porous Magnesium oxide (MgO) particles have been applied to generate mixed matrix membranes (MMM) for the dehydration of iso-propanol by pervaporation. A modified membrane fabrication procedure has been developed to prepare membranes with higher separation efficiency. FESEM and DSC characterizations confirm that the MMMs produced have intimate polymer/particle interface; the nanosize crystallites on MgO surface may interfere with the polymer chain packing and induce chains rigidification upon the particle surface. It is observed that Matrimid®/MgO MMMs generally have higher selectivity, but lower permeability relative to the neat Matrimid® dense membrane. The highest selectivity is obtained with MMM containing 15 wt. % MgO. The selective sorption and diffusion of water in the MgO particles, and the polymer/particle interface properties combine to lead to the earlier phenomena. The investigation on the effect of feed water composition on the pervaporation performance reveals that the addition of MgO can show the selectivity-enhancing effects if the feed water concentration is lower than 30 wt. %. In the dehydration of isopropanol aqueous solution with 10 wt. % water, the selectivity of the MMMs is around 2,000, which is more than twice of 900 of neat polymeric membrane. This makes MMMs extremely suitable for breaking the azeotrops of water/iso-propanol. Gas permeation tests are also conducted using O2 and N2 to determine the microscopic structure of the MMMs, and to investigate the relationship between pervaporation and gas separation performance. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] Polymeric systems for amorphous ,9 -tetrahydrocannabinol produced by a hot-melt method.JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2006Part II: Effect of oxidation mechanisms, chemical interactions on stability Abstract The objectives of the present research investigations were to (i) elucidate the mechanism for the oxidative degradation of ,9 -tetrahydrocannabinol (THC) in polymer matrix systems prepared by a hot-melt fabrication procedure, and (ii) study the potential for controlling these mechanisms to reduce the degradation of THC in solid dosage formulations. Various factors considered and applied included drug-excipient compatibility, use of antioxidants, cross-linking in polymeric matrices, microenvironment pH, and moisture effect. Instability of THC in polyethylene oxide (PEO)-vitamin E succinate (VES) patches was determined to be due to chemical interaction between the drug and the vitamin as well as with the atmospheric oxygen. Of the different classes and mechanisms of antioxidants studied, quenching of oxygen by reducing agents, namely, ascorbic acid was the most effective in stabilizing THC in PEO-VES matrices. Only 5.8% of the drug degraded in the ascorbic acid-containing patch as compared to the control (31.6%) after 2 months of storage at 40°C. This coupled with the cross-linking extent and adjustment of the pH microenvironment, which seemed to have an impact on the THC degradation, might be effectively utilized towards stabilization of the drug in these polymeric matrices and other pharmaceutical dosage forms. These studies are relevant to the development of a stable transmucosal matrix system for the therapeutic delivery of amorphous THC. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:2473,2485, 2006 [source] Piezoelectric Multilayer Ceramic/Polymer Composite Transducer with 2,2 ConnectivityJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006Chang-Bun Yoon A multilayer piezoelectric ceramic/polymer composite with 2,2 connectivity was fabricated by thermoplastic green machining after co-extrusion. The multilayer ceramic body was composed of piezoelectrically active lead zirconate titanate (PZN),lead zinc niobate (PZN)-lead zirconate titanate (PZT) layers and electrically conducting PZN,PZT/Ag layers. After co-extruding the thermoplastic body, which consisted of five piezoelectric layers interspersed with four conducting layers, it was computer numeric-controlled machined to create periodic channels within it. Following binder burnout and sintering, an 18 vol% array of 190 ,m thin PZT slabs with a channel size of 880 ,m was fabricated. The channels were filled with epoxy in order to fabricate a PZN,PZT/epoxy composite with 2,2 connectivity. The piezoelectric coefficient (effective d33) and hydrostatic figure of merit (dh×gh) of the PZN,PZT/epoxy composite were 1200 pC/N and 20 130 × 10,15 m2/N, respectively. These excellent piezoelectric characteristics as well as the relatively simple fabrication procedure will contribute in widening the application range of the piezoelectric transducers. [source] Preparation and Properties of PVC Ternary Nanocomposites Containing Elastomeric Nanoscale Particles and Exfoliated Sodium-MontmorilloniteMACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2006Qingguo Wang Abstract Summary: A novel rigid PVC ternary nanocomposite containing NBR-ENP and untreated Na-MMT has been fabricated. X-ray diffraction XRD, TEM and SEM observations revealed that the untreated Na-MMT was exfoliated and most NBR-ENPs (about 90 nm) were separately dispersed in the PVC matrix. DMTA and TGA demonstrated that the PVC ternary nanocomposites had a higher glass transition temperature and a higher decomposition temperature than neat PVC, while the toughness increased simultaneously. Combustion tests showed that the exfoliated clay in the PVC/NBR-ENP/MMT ternary nanocomposites did not improve the flame retardancy after ignition under strong heat flux. Schematic diagram of the fabrication procedure of PVC/NBR-ENP/Na-MMT ternary nanocomposites. [source] The effect of crystallization technology and gate insulator deposition method on the performance and reliability of polysilicon TFTsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2008Despina C. Moschou Abstract Polysilicon TFTs were fabricated using solid phase crystallization (SPC) and also two different excimer laser annealing techniques (ELA) for polysilicon crystallization. Moreover, we tried two different gate oxide deposition methods, using PECVD or TEOS LPCVD. Comparing the characteristics of the fabricated TFTs, we were able to probe the effects of the polysilicon crystallization techniques and the gate oxide deposition methods on TFT performance and reliability. This way, an optimization of the TFT fabrication procedure could be possible. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Materials Fabricated by Micro- and Nanoparticle Assembly , The Challenging Path from Science to EngineeringADVANCED MATERIALS, Issue 19 2009Orlin D. Velev Abstract We classify the strategies for colloidal assembly and review the diverse potential applications of micro- and nanoparticle structures in materials and device prototypes. The useful properties of the particle assemblies, such as high surface-to-volume ratio, periodicity at mesoscale, large packing density, and long-range ordering, can be harnessed in optical, electronic, and biosensing devices. We discuss the present and future trends in the colloidal- assembly field, focusing on the challenges of developing fabrication procedures that are rapid and efficiently controlled. We speculate on how the issues of scalability, control, and precision could be addressed, and how the functionality of the assemblies can be increased to better match the needs of technology. [source] | |||||||||||||