179,340 research outputs found
Moisture conditions in coated wood panels during 18 months natural weathering at five sites in Europe
Wood moisture content of coated panels of Scots pine sapwood was recorded during 18 months natural weathering in Vienna by logging electric resistance and temperature near the surface. Eight coating systems with various film thicknesses were used, including three solvent borne alkyd stains, three water borne acrylic stains and two water borne acrylic paints. At five sites in Europe wood moisture content of panels coated with three solvent borne alkyd stains, a brow acrylic stain and a white opaque acrylic paint was recorded weekly by changes in panel mass. Fluctuations in wood moisture content were influenced by the film thickness, moisture protection and colour of the coating systems used. Degradation phenomena led to decreasing moisture protection of less durable coating systems over time of exposure. Differences between the exposure sites were relatively low, except the site in the UK where moisture conditions were higher
UV Degradation of the Optical Properties of Acrylic for Neutrino and Dark Matter Experiments
UV-transmitting (UVT) acrylic is a commonly used light-propagating material
in neutrino and dark matter detectors as it has low intrinsic radioactivity and
exhibits low absorption in the detectors' light producing regions, from 350 nm
to 500 nm. Degradation of optical transmittance in this region lowers light
yields in the detector, which can affect energy reconstruction, resolution, and
experimental sensitivities. We examine transmittance loss as a result of short-
and long-term UV exposure for a variety of UVT acrylic samples from a number of
acrylic manufacturers. Significant degradation peaking at 343 nm was observed
in some UVT acrylics with as little as three hours of direct sunlight, while
others exhibited softer degradation peaking at 310 nm over many days of
exposure to sunlight. Based on their measured degradation results, safe time
limits for indoor and outdoor UV exposure of UVT acrylic are formulated.Comment: 13 pages, 6 figures, 3 tables; To be submitted to Journal of
Instrumentatio
Long-Term Testing and Properties of Acrylic for the Daya Bay Antineutrino Detectors
The Daya Bay reactor antineutrino experiment has recently measured the
neutrino mixing parameter sin22{\theta}13 by observing electron antineutrino
disappearance over kilometer-scale baselines using six antineutrino detectors
at near and far distances from reactor cores at the Daya Bay nuclear power
complex. Liquid scintillator contained in transparent target vessels is used to
detect electron antineutrinos via the inverse beta-decay reaction. The Daya Bay
experiment will operate for about five years yielding a precision measurement
of sin22{\theta}13. We report on long-term studies of poly(methyl methacrylate)
known as acrylic, which is the primary material used in the fabrication of the
target vessels for the experiment's antineutrino detectors. In these studies,
acrylic samples are subjected to gaseous and liquid environmental conditions
similar to those experienced during construction, transport, and operation of
the Daya Bay acrylic target vessels and detectors. Mechanical and optical
stability of the acrylic as well as its interaction with detector liquids is
reported.Comment: 17 pages, 13 figures Submitted to JINS
Acrylic purification and coatings
Radon (Rn) and its decay daughters are a well-known source of background in
direct WIMP detection experiments, as either a Rn decay daughter or an alpha
particle emitted from a thin inner surface layer of a detector could produce a
WIMP-like signal. Different surface treatment and cleaning techniques have been
employed in the past to remove this type of contamination. A new method of
dealing with the problem has been proposed and used for a prototype acrylic
DEAP-1 detector. Inner surfaces of the detector were coated with a layer of
ultra pure acrylic, meant to shield the active volume from alphas and recoiling
nuclei. An acrylic purification technique and two coating techniques are
described: a solvent-borne (tested on DEAP-1) and solvent-less (being developed
for the full scale DEAP-3600 detector).Comment: Proceedings of Topical Workshop on Low Radioactivity Techniques (LRT
2010), SNOLAB, Sudbury, Canada, Aug 28-29, 201
Phase Behavior of Polyelectrolyte Block Copolymers in Mixed Solvents
We have studied the phase behavior of the poly(n-butyl
acrylate)-b-poly(acrylic acid) block copolymer in a mixture of two miscible
solvents, water and tetrahydrofuran (THF). The techniques used to examine the
different polymers, structures and phases formed in mixed solvents were static
and dynamic light scattering, small-angle neutron scattering, nuclear magnetic
resonance and fluorescence microscopy. By lowering the water/THF mixing ratio
X, the sequence unimers, micron-sized droplets, polymeric micelles was
observed. The transition between unimers and the micron-sized droplets occurred
at X = 0.75, whereas the microstructuration into core-shell polymeric micelles
was effective below X = 0.4. At intermediate mixing ratios, a coexistence
between the micron-sized droplets and the polymeric micelles was observed.
Combining the different aforementioned techniques, it was concluded that the
droplet dispersion resulted from a solvent partitioning that was induced by the
hydrophobic blocks. Comparison of poly(n-butyl acrylate) homopolymers and
poly(n-butyl acrylate)-b-poly(acrylic acid) block copolymers suggested that the
droplets were rich in THF and concentrated in copolymers and that they were
stabilized by the hydrophilic poly(acrylic acid) moieties.Comment: 11 pages, 12 figures, to appear in Macromolecule
Development of battery separator material process Interim report
Dose rate of irradiation grafting for polyethylene film with acrylic aci
Silver-Zinc Battery Separator Material Development
Ethylene/acrylic acid separators for silver zinc battery application
Development of battery separator material process Quarterly report, 2 Jul. - 30 Sep. 1969
Battery separator materials from acrylic acid grafting solution with polyethylene film effect
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