Stabilization and degradation of acetal copolymers.
Item
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Title
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Stabilization and degradation of acetal copolymers.
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Identifier
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AAI9111462
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identifier
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9111462
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Creator
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Pesce, Rose Ann.
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Contributor
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Adviser: Nan-Loh Yang
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Date
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1988
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Polymer
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Abstract
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Polyacetal copolymers are technically important macromolecules that are competitive with metals, ceramics and nylons in many applications. As the simplest form of aliphatic polyethers, they are of fundamental interest. The present investigation involves detailed studies aimed at the improvement of polyacetal stability.;Radical and acidolytic degradation of a model trioxane-ethylene oxide copolymer in solution were examined. Degradation products, identified by NMR spectroscopy, have been confirmed to be formaldehyde, formic acid and cyclic acetals (1,3-dioxolane, 1,3,5-trioxepane, 1,3,5-trioxane and 1,3,5,7-tetraoxane). The formation of these cyclic acetals is attributed to backbiting of the depolymerizing chain end.;A method for evaluating formaldehyde-accepting stabilizers for use in polyacetal systems has been developed. Based on acceptor-adduct equilibrium studies, conducted by titration, NMR spectroscopy and thermal analysis, the relative efficiencies of a series of acceptors was determined.;The need for polyacetals capable of binding stabilizers led to the synthesis of three new functionalized acetal copolymers. The first, a copolymer of trioxane and 1,3-dioxep-5-ene, yields a cis-2-butene stopper unit. This thermally stable copolymer has been found to have crystallinity comparable to trioxane-ethylene oxide copolymers. Examples of copolymer modification are reported. Resistance to bromine degradation has also been demonstrated. M{dollar}\sb{lcub}\rm n{rcub}{dollar} and M{dollar}\sb{lcub}\rm v{rcub}{dollar} have been found to be as high as 6 {dollar}\times{dollar} 10{dollar}\sp4{dollar} and 8 {dollar}\times{dollar} 10{dollar}\sp4{dollar} respectively.;The second, a copolymer of trioxane and glycerol formal, is thermally stable and has pendant hydroxy and methylol groups. M{dollar}\sb{lcub}\rm v{rcub}{dollar} is estimated to be less than 5 {dollar}\times{dollar} 10{dollar}\sp3{dollar}. Equilibrium studies of the glycerol formal comonomer are also discussed.;The third, a copolymer of trioxane and glycidyl acrylate, is a thermally stable, crosslinked copolymer with pendant acrylate groups. DSC analysis of copolymers with glycidyl acrylate feeds ranging from 4 to 24 weight percent shows crystallinities ranging from 36 to 11%.;Each of the new copolymers has a functionalized comonomer unit which serves as both a stopper against unzipping and a site for further modification.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
