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Powder Dispersion (powder + dispersion)

Distribution by Scientific Domains

Polymers and Materials Science	60%

Selected Abstracts

Electrostatics of pharmaceutical inhalation aerosols

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2009
Philip Chi Lip Kwok
Abstract Objectives This review focuses on the key findings and developments in the rapidly expanding research area of pharmaceutical aerosol electrostatics. Key findings Data from limited in-vivo and computational studies suggest that charges may potentially affect particle deposition in the airways. Charging occurs naturally in the absence of electric fields through triboelectrification, that is contact or friction for solids and flowing or spraying for liquids. Thus, particles and droplets emitted from pulmonary drug delivery devices (dry powder inhalers, metered dose inhalers with or without spacers, and nebulisers) are inherently charged. Apparatus with various operation principles have been employed in the measurement of pharmaceutical charges. Aerosol charges are dependent on many physicochemical parameters, such as formulation composition, device construction, relative humidity and solid-state properties. In some devices, electrification has been purposefully applied to facilitate powder dispersion and liquid atomisation. Summary Currently, there are no regulatory requirements on characterising electrostatic properties of inhalation aerosols. As research in this area progresses, the new knowledge gained may become valuable for the development and regulation of inhalation aerosol products. [source]

Cardanol: A New Dispersant for Alumina in Toluene

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2000
Kuttan Prabhakaran
Cardanol, which is a naturally occurring C15 unsaturated aliphatic chain-substituted phenol derived from cashew nut shell liquid, was used as a dispersant for alumina in toluene. Adsorption data, along with the results of sedimentation studies, green density, and slurry viscosity (as a function of dispersant concentration), suggest that cardanol adsorption initially proceeded through surface coverage by a phenolic group that lies flat on the surface and that the best powder dispersion occurred at surface saturation by more closely packed end-on adsorbed cardanol molecules. The alkyl-chain unsaturation significantly contributed to dispersion, such that the saturation by hydrogenation led to an increase in the slurry viscosity by a factor of ,2.5. Concentrated slurries generally showed shear-thinning flow behavior, and the measured viscosity of a highly concentrated (53 vol%) slurry was <1 Pa·s at a shear rate of 93 s,1. [source]

Effects of stearic acid on the interface and performance of polypropylene/superfine down powder composites

POLYMER COMPOSITES, Issue 12 2009
Xin Liu
To manufacture the hygroscopic sheets available for functional application, superfine down powder (SDP) and stearic acid modified superfine down powder (MSDP) were, respectively, blended and extruded with polypropylene (PP) to produce composite pellets, and the extruded pellets were hot-pressed into composite sheets. The chemical reaction between SDP and stearic acid was characterized using the attenuated total reflection attachment on the Fourier transform infrared. PP/MSDP composites showed more uniform powder dispersion in PP matrix, higher compatibility, and better mechanical properties than that of PP/SDP composites, which showed an evident decrease in tensile strength and elongation at break compared with pure PP. It was worth noting that the Young's modulus of PP/SDP composites was higher than that of pure PP, but lower than that of PP/MSDP composites. The addition of SDP led to a large increase in water absorption of PP/SDP composites. However, the water absorption of PP/MSDP composites decreased slightly compared with that of PP/SDP composites. Furthermore, the effects of SDP and MSDP on the microstructural and thermal properties of different composites were also investigated, respectively. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

Characterisation of pressure-treated skimmed milk powder dispersions: application of NMR spectroscopy

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2002
Colin D Hubbard
Abstract Skimmed milk powder (SMP) (bovine) and skimmed milk powder/sucrose dispersions before, during and after high-pressure treatment have been studied by nuclear magnetic resonance (NMR) spectroscopy (principally P-31). The P-31 spectra of samples at 293,K before and after pressure (400,600,MPa) treatment were not significantly different from one another, whether or not sucrose was present. This indicates that physicochemical changes relating to phosphorus-containing components occurring during a pressure cycle are either reversible or result in re-immobilisation, while protein components may be rearranged. The P-31 NMR spectra of these dispersions at 293,K under pressure (100,300,MPa) showed that pressure caused a considerable increase in the free inorganic phosphate concentration and that the increase was proportional to the magnitude of pressure. Decompression to ambient caused an exact reversal of this trend. These findings are discussed in terms of characterisation and properties of pressure-treated SMP dispersions by other methods and techniques. © 2002 Society of Chemical Industry [source]

Nanodiamond Tipped and Coated Conical Carbon Tubular Structures,

CHEMICAL VAPOR DEPOSITION, Issue 7-8 2008
Boris Chernomordik
Abstract Studies of diamond nucleation and growth on conical carbon tubular structures show that the nucleation preferentially occurs at the tips, but only occurs on the sidewalls when they are pretreated with diamond or other powder dispersions, forming a nanodiamond coating. The high-resolution transmission electron microscopy (HRTEM) studies reveal that the diamond nucleation on the sidewalls may proceed through the formation of diamond nuclei within the walls at subsurface damage sites caused during pretreatment. In the case of experiments with low atomic hydrogen conditions, carbon onion structures are observed on the sidewalls but only with pretreatments. [source]