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Composition Ratios (composition + ratio)

Distribution by Scientific Domains

Polymers and Materials Science	80%

Selected Abstracts

Gas-phase-assisted surface polymerization of methyl methacrylate with Fe(0)/TsCl initiator system

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007
Yoshito Andou
Abstract To obtain a high polymer coated Fe(0) surface, gas-phase-assisted surface polymerization (GASP) of methyl methacrylate (MMA) was investigated using a zero-valent iron (Fe(0))/p -toluene sulfonylchloride (TsCl) initiator system, resulting in successful high polymer production on the solid surface. GASP was found to be initiated by radical species that might have been generated via redox reactions with Fe(0), Fe(II), Fe(III), and TsCl. From 1H-NMR analysis, the p -toluene sulfonyl group was found at one end of the polymer chain. The molecular weight of obtained PMMA drastically decreased with increase in the composition ratio of Fe(0) in the initiator system, and increased with increase in polymer yield. From the results, it was assumed that the physically controlled polymerization of MMA proceeded by immobilized active species at gas,solid interfaces. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1879,1886, 2007 [source]

Effect of Sample Configuration on the Morphology of Foamed LDPE/PP Blends Injection Molded by a Gas Counterpressure Process

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2007
Georgi Kotzev
Abstract Blends of isotactic poly(propylene) and low-density polyethylene with different composition ratios were prepared through direct melt compounding on a twin-screw extruder. The specimens with various geometric configurations were injection-molded using a gas counterpressure process, using blends to which 0.5 wt.-% of a blowing agent was added. The influence of blend composition and specimen geometry on the structure and morphology of the samples was investigated by SEM and WAXS. The thermal behavior of the blends was analyzed by DSC. It was found that the morphology of each region depended on the composition ratio and specimen geometry. [source]

Synthesis of Well-Defined Statistical and Diblock Copolymers of Acrylamide and Acrylic Acid by Inverse Miniemulsion Raft Polymerization

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 18 2010
Liu Ouyang
Abstract Well-defined statistical and diblock copolymers with acrylamide and acrylic acid were synthesized by inverse miniemulsion RAFT polymerization. Statistical copolymers with various composition ratios were synthesized. Compositional drift was observed during polymerization. Acrylamide was polymerized with a water-soluble initiator (VA-044) at 60,°C to give the RAFT-agent-containing acrylamide homopolymer with a narrow molecular-weight distribution (PDI,<,1.3), which was then chain-extended with acrylic acid to obtain the diblock copolymer. [source]

Effect of Sample Configuration on the Morphology of Foamed LDPE/PP Blends Injection Molded by a Gas Counterpressure Process

Combustion Measurements of Fuel-Rich Aluminum and Molybdenum Oxide Nano-Composite Mixtures

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2010
Tim Bazyn
Abstract Fuel rich nano-composite powders of aluminum and molybdenum oxide were tested for ignition and combustion behind the incident and reflected shock waves in a shock tube. The powders consisted of approximately 10,,m particles, each of which contained Al and MoO3 mixed by mechanical alloying on the nano-scale. These powders were aluminum rich with composition ratios of 4,:,1, 8,:,1, and 16,:,1 Al,:,MoO3 by mass. Ignition tests were performed behind incident shocks for temperatures in the range of 900 to 1500,K. From these tests, ignition delay times were obtained, and some information on combustion duration was also derived. Samples were tested in air at 0.2,MPa, and compared against nano-Al, 2.7,,m Al, and 10,,m Al baselines. Ignition results for the baseline Al cases were as expected: 10,,m Al not igniting until 2000,K, 2,,m Al igniting down to ,1400,K, and n-Al igniting as low as 1150,K. The thermite samples showed considerable improvement in ignition characteristics. At the lowest temperature tested (900,K), both the 8,:,1 and 4,:,1 samples ignited within 250,,s. The 16,:,1 sample (94% Al) ignited down to 1050,K , which represents an improvement of roughly 1000,K over baseline Al with only a small energetic penalty. In all cases, the ignition delay increased as the amount of MoO3 in the composite was reduced. The 4,:,1 nano-composite material ignited as fast or faster than the n-Al samples. Ignition delay increased with decreasing temperature, as expected. Emission spectra and temperature data were also taken for all samples using high-speed pyrometry and time-integrated spectroscopy. In these cases, measurements were made behind the reflected shock using end-wall loading, though the conditions (temperature, pressure, and gas composition) were identical to the incident shock tests. Spectroscopy showed strong AlO features in all the samples, and the spectra fit well to an equilibrium temperature. Broadband, low resolution spectra were also fit to continuum, gray body temperatures. In general, the observed temperatures were reasonably close to 3500,K, which is similar to the combustion temperatures of pure aluminum under these conditions. [source]