Search results for "Metallurgy"
showing 10 items of 1419 documents
Biologizing titanium alloy implant material with morphogenetically active polyphosphate
2015
As a further step towards a new generation of bone implant materials, we developed a procedure for biological functionalization of titanium alloy surfaces with inorganic calcium polyphosphate (Ca-polyP). This polymer has been demonstrated to exhibit morphogenetic activity. The coating of titanium oxidized Ti-6Al-4V scaffolds with biologically active amorphous Ca-polyP microparticles is formed by Ca2+ ion bridges to the silane coupling agent APTMS. This surface is durable and stable as an almost homogeneous Ca-polyP layer onto the metal. The homogenously coated Ca-polyP titanium scaffold was found to be biologically active and supported the growth and functional activity of bone cell-related…
Activity of Antimicrobial Silver Polystyrene Nanocomposites.
2012
A simple technique based on doping polymers within situgenerated silver nanoparticles (Ag/PS films) has been developed. In particular, an antiseptic material has been prepared by dissolving silver 1,5-cyclooctadiene-hexafluoroacetylacetonate in amorphous polystyrene, and the obtained solid solution has been heated for ca. 10 s at a convenient temperature (180°C). Under such conditions the metal precursor decomposes producing silver atoms that diffuse into the polymer and clusterize. The antimicrobial characteristics of the resulting polystyrene-based material have been accurately evaluated towardEscherichia coli (E. coli)comparing the cytotoxicity effect of 10 wt.% and 30 wt.% (drastic and …
Effect of stress and temperature on the thermomechanical degradation of a PE-LD/OMMT nanocomposites
2014
Thermomechanical degradation of nanocomposites is a topical issue that has not been fully investigated as demonstrated by the low number of papers available in the literature regarding this spe- cific aspect. In particular, with regards to low density polyethylene/clay nanocomposites, the degrada- tion behavior is very complex since it involves the degradation paths of both the polymer matrix and the organomodified nanoclay. In the present work, the effects of mechanical stress and temperature on the thermomechanical behavior of PE-LD/organomodified clay nanocomposites and the degradation paths were investigated by rheological, FT-IR and mechanical methods. The results have shown that the t…
Effect of physical aging on the low-frequency vibrational density of states of a glassy polymer
2003
The effects of the physical aging on the vibrational density of states (VDOS) of a polymeric glass is studied. The VDOS of a poly(methyl methacrylate) glass at low-energy (<15 meV), was determined from inelastic neutron scattering at low-temperature for two different physical thermodynamical states. One sample was annealed during a long time at temperature lower than Tg, and another was quenched from a temperature higher than Tg. It was found that the VDOS around the boson peak, relatively to the one at higher energy, decreases with the annealing at lower temperature than Tg, i.e., with the physical aging.
Relationship between structure of drawn polymers and molecular motion
1971
In order to study the relationship between structure and molecular motion, drawn polymers are more suitable than isotropic samples since their morphology can be characterized more easily by quantitative methods such as small angle X-ray scattering (SAXS) and electron microscopy (EM). The effects of changes in morphological structure on molecular motion are demonstrated by comparing the results of the SAXS and EM measurements with the dynamic mechanical behavior of drawn polyethylene. In addition the NMR broad line spectra of these samples were analyzed and the influence of annealing conditions and external stress was investigated.
An Appraisal by M.I.P of the Changes Induced in the Microstructure of Complex Sulfide Ores by Reactive Thermal Treatments in H2 and N2
1991
Summary Changes in the microstructure of complex sulfide ores resulting from reactive thermal treatments in either H2 or N2 were investigated qualitatively by combined scanning electron microscopy and X ray microanalysis, and quantitatively by mercury intrusion porosimetry (MIP) and mercury pycnometry. With increasing treatment temperature, we successively observed: 1) the development of fractures, preferentially at interfaces between the various mineral components, 2) the development of meso and macropores and the simultaneous swelling of the solids and 3) the crystallization or recrystallization of the metal or sufide phase products. In all cases the specific pore volume and mean pore dia…
Combined thermal evaporated and solution processed organic light emitting diodes
2011
Abstract Highly efficient, partly solution processed phosphorescent red, green and white organic light emitting diodes with small molecular weight host materials are prepared from commercially available starting compounds. Starting from an evaporated reference device, layers are stepwise replaced by solution processed layers. Replacing the evaporated hole transport layer by a solution processed polymer interlayer does not affect the performance and allows spincoating of the emissive layer after annealing of the polymer. Devices with, next to the spincoated hole injection and transport layer, a solution processed emission layer show similar characteristics and efficiencies as the reference d…
Controlled solvent vapour annealing for polymer electronics
2009
Solvent vapour annealing (SVA) is demonstrated as an attractive method to anneal polymer blend and block copolymer thin films at low temperatures. It is especially suitable for organic electronics, where sensitive materials with strong intermolecular interactions are used. We demonstrate the effect of solvent vapour exposure on the film properties of a perylene bisimide acrylate (PPerAcr) side-chain polymer with strong crystallinity at the perylene bisimide moieties. We record the film thickness, light absorption and fluorescence as a function of the relative solvent vapour pressure. At a certain threshold of relative solvent vapour pressure, we observe a disruption of the π–π stacking, whi…
Surface and bulk ordering in thin films of a symmetrical diblock copolymer
2013
Amphiphilic diblock copolymers have the ability to adapt their surface's molecular composition to the hydrophilicity of their environment. In the case of about equal volume fractions of the two polymer blocks, the bulk of these polymers is known to develop a laminar ordering. We report here our investigation of the relationship between bulk ordering and surface morphology/chemical composition in thin films of such an amphiphilic diblock copolymer. Upon annealing in vacuum, the expected lamella ordering in the bulk of the film is observed and we find the morphology of the film surface to be defined by the thickness of the as-deposited film: If the as-deposited thickness matches the height of…
Thermal Analysis, Mechanical and Rheological Behaviour of Melt Manufactured Polyethylene/Liquid Crystal Polymer Blends
2011
Modification of properties of conventional thermoplastics with thermotropic liquid crystal polymers, from one hand, allows decrease their viscosities, substantially facilitating processing conditions, and, from another hand, allows increase their exploitation properties. Orientation of the labile structure of liquid crystal polymer in extrusion or injection moulding causes specific reinforcement (so-called self-reinforcement) to occur in the blends containing liquid crystal polymer. Up to now the effect of self-reinforcement is mostly investigated in the blends, containing considerable amount of liquid crystal polymer. In this research the effect of minor amounts of liquid crystalline co-po…