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Experimental determination of sequence length distribution of hard segments in polyester-polyurethanes

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Resumo:A new analytical procedure based on selective acid hydrolysis was developed to measure the chain length distribution of hard segments (HSCLD) of polyester-polyurethanes. It was tested with polymers made from 4,4'-methylenebis(pheny1 isocyanate), 1,6-hexanediol, and a,w-dihydroxypoly- (hexamethylene adipate) with number-average molecular weight 2200. Heating samples with 0.25 M HC1 solution in dimethyl sulfoxide with 8.2% water for 36 h leads to nearly complete hydrolysis of the ester groups, leaving the urethanes largely unaffected. The resulting mixture of oligomers can be analyzed by size exclusion chromatography, using dimethylformamide at room temperature as the solvent. Experimentally measured HSCLDs were most often very different from those theoretically predicted for homogeneous reaction.
Autores principais:Barreiro, M.F.
Outros Autores:Dias, Rolando; Costa, Mário Rui
Assunto:Sequence Polyester-Polyurethanes
Ano:1994
País:Portugal
Tipo de documento:artigo
Tipo de acesso:acesso restrito
Instituição associada:Instituto Politécnico de Bragança
Idioma:inglês
Origem:Biblioteca Digital do IPB

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