Spelling suggestions: "subject:"Methyl andmethacrylate"" "subject:"Methyl ethylmethacrylate""
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An ESR study of the radicals occluded during emulsion polymerisationsCutting, Graham Russell January 1996 (has links)
No description available.
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Novel stabilisers for polymerisations in supercritical carbon dioxideGriffiths, Rhiannon M. T. January 2002 (has links)
No description available.
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The usefulness of task-based exposure data incharacterising work tasks that produce potentially high short-term exposuresChester, Sean John 01 June 2009 (has links)
Introduction: Single sample TWA samples collected over an 8-hour shift have the
potential to mask elevated exposures, excursions or “peaks” that may have occurred
thus permitting situations where workers are over-exposed or indeed over-dosed. The
objectives of this study, undertaken in a small acrylic sheet manufacturing plant, are
therefore to identify tasks that have the potential to exceed short-term occupational
exposure levels and then simultaneously monitor employees undertaking these tasks for
8-hour TWA and Short-Term exposure concentrations. The results obtained from this
sampling are then compared to their respective legal limits and then finally correlated to
establish their statistical significance.
Materials and Methods: The study setting comprises a syrup room wherein two
employees are assigned per shift. Employees in this setting manufacture an acrylic
“syrup” which is achieved by dosing raw materials into any one of 13 mixing vessels.
Whilst mixing, these vessels also heat the ingredients until the required viscosity is
reached. This “syrup” comprising mostly of liquid methyl methacrylate, is then
decanted into a pressure vessel from where it is pipe-fed into a casting chamber and
finally poured between two glass sheets. When cured, the final product is stored and
sold as a clear or tinted acrylic sheet. All operations with this area are therefore
associated with facilitating the syrup manufacture. Personal 8-hour TWA and Task-
Based measurements of methyl methacrylate vapour were simultaneously obtained from
the breathing zones of six employees over five separate shifts. These employees
routinely work within the setting and also undertake tasks that have the potential to
exceed the Short-Term Occupational Exposure Limit (ST-OEL) for methyl
methacrylate vapour. Tasks were studied and those selected for quantitative monitoring
were captured using a qualitative risk assessment tool. These selections were based on
studying each task to establish the employee’s exposure probability and severity i.e.
whether performing the task could indeed lead to excessive Short-Term exposures.
Eight-hour TWA monitoring was undertaken using activated carbon 3M 3500 passive
monitoring badges which were attached to each of the subject’s breathing zone and left
over 80 % of the shift. The task-based measurements were obtained by using a Drager
PAC III electro-chemical monitoring instrument, which was also placed in each
each
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subject’s breathing zone, and provided real-time exposure data whilst the employees
were undertaking the various tasks.
Results: All measurements (N = 116) were obtained over a series of 5 full-shift
monitoring periods. When analysed, 8 of the 10 of the TWA samples returned results
that were below the 8-hour TWA OEL. Of the 106 task-based measurements obtained
for the nine identified tasks, when averaged, 89.1 % of results exceeded the ST-OEL.
When the TWA and ST measurements were correlated, only one of the nine tasks were
statistically significant in their correlation. This correlation coefficient was however
highly statistically significant (r = 0.339, p = 0.032 and r = 0.337, p = 0.022
respectively). Both negative and positive correlations were obtained however these were
statistically insignificant.
Discussion: A significantly higher proportion of the sample results were above the STOEL
than the 8-hour TWA OEL concentrations contributing to the argument that ST
exposure monitoring may add additional insight to employees’ exposure profiles. A
major limitation of the study is however the small sample size, which makes it difficult,
due to inter-worker variability amongst other factors, to extrapolate the results and their
corresponding interpretations to larger, more generalised occupational hygiene
monitoring scenarios.
Conclusion: The results obtained therefore support the assertion that the inclusion of
short-term monitoring is important in characterising employee exposures in situations
where these tasks are themselves potential sources of significant chemical exposures.
Recommendations: As a basis for undertaking any form of monitoring and particularly
in settings where short-term, task-based exposures may exist, the importance of
undertaking a systematic approach to hazard identification and risk profiling via the use
of a known risk assessment tool to compile a air sampling programme, has been
demonstrated in the results of this research. Further research that specifically addresses
the problem of characterising workplace exposures would be useful in larger study
populations as well as occupational settings which expose employees to the various
types of airborne contaminant e.g. fume, mists, particulates and gases.
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Radiopurity measurement of acrylic for the DEAP-3600 dark matter experimentNantais, Corina 16 January 2014 (has links)
The liquid argon target of the DEAP-3600 dark matter detector is contained by an extremely radiopure acrylic vessel. Alpha decays from the inner surface of the acrylic vessel are a source of background. If a fraction of the alpha energy is observed, or if the recoiling nucleus from the alpha decay is observed, the event will not be separated from a dark matter candidate event. In addition to the low level of inherent contamination from uranium and thorium, the Pb-210 from Rn-222 diffusion during manufacturing must be measured. The limit for the DEAP-3600 acrylic vessel is 1.1 × 10^−20 g/g Pb-210. By vaporizing a large quantity of acrylic and counting the concentrated residue with an ultralow background HPGe well detector and a low background alpha spectrometer, the bulk acrylic was found to have an upper limit of 10^−19 g/g Pb-210. The design, installation, commissioning, operation, and analysis for various aspects of the acrylic assay are described. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2014-01-14 19:27:47.533
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Modification of bis(ditertiarybutylphosphinomethyl)benzene for improved catalyst separation and stability /Parnham, Benjamin Lee. January 2007 (has links)
Thesis (Ph.D.) - University of St Andrews, May 2007. / Restricted until 3rd May 2012.
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Polymerization of monomers within hoop pine to enhance harness for appearance grade applications /Chen, Lan. January 2004 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliographical references.
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Restraining the aggregations of luminescent iridium complex and polybenzoxazine by blending with polymersMao, Chin-hsin 26 July 2007 (has links)
Luminescent molecules and polymers are active component in light-emitting diodes; however, the aggregation and excimer formation in concentrated solution or in the solid film states had limited their applications. Therefore, this study used poly(methyl methacrylate) (PMMA) as separator to prevent the formations of aggregate and excimer and to enhance quantum efficiency. Basically, two systems are involved:
(1) Inorganic phosphorescent irdium complex
PMMA was doped with inorganic iridium complex IrQB by using THF as solvent. IrQB/PMMA films prepared from dilute solutions exhibit two emissions centered at 560 and 640 nm, respectively; in contrast, only 640-nm emission was observed for films from concentrated solutions. Experimentally, these two bands showed variations on the emission intensity with increasing temperature. Aggregation of IrQB is suggested to be responsible for the 560-nm emission. Chain conformation of PMMA in the solution state strongly affects the incorporated IrQBs and their emission properties.
(2) Polybenzoxazines
Polybenzoxazines with the built-in fluorenscent fluorine moiety are linear in nature; however, the inherent hydrogen-bond (H-bond) interactions in polybenzoxazines decrease the inter-chain distance and cause the chain aggregation. With the added PMMAs, new H-bonding from the carbonyl groups in PMMA and the hydroxyl groups in polybenzoxazine enhances the mutual miscibility between these two components and decreases the possibility of aggregate formation in polybenzoxazines. Quantum efficiency is therefore promoted by this approach.
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The solid state polymerization of hydrated calcium acrylate and hydrated barium methacrylate.Costaschuk, Fred Michael. January 1970 (has links)
No description available.
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The kinetics and mechanism of the polymerization of methyl methacrylate initiated by organomagnesium compoundsBateup, Brett Oliver January 1974 (has links)
Reprints of 3 articles published by the author included in back of book / 1v. (various paging) : ill. ; 26 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1974) from the Dept. of Physical and Inorganic Chemistry, University of Adelaide
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Graft polymerization of methyl methacrylate onto polytetrafluoroethylene free radicalsDonato, Karen Ann. January 1985 (has links)
Thesis (M.S.)--Ohio University, November, 1985. / Title from PDF t.p.
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