Utilize este identificador para referenciar este registo: http://hdl.handle.net/10198/343
Título: Experimental determination of sequence length distribution of hard segments in polyester-polyurethanes
Autor: Barreiro, M.F.
Dias, Rolando
Costa, Mário Rui
Palavras-chave: Sequence
Polyester-Polyurethanes
Data: 1994
Editora: American Chemical Society
Citação: Barreiro, M.F.; Dias, Rolando; Costa, Mário (1994) - Experimental determination of sequence length distribution of hard segments in polyester-polyurethanes. Macromolecules. ISSN 0024-9297. 27:26, p.7650-7653
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.
Peer review: yes
URI: http://hdl.handle.net/10198/343
ISSN: 0024-9297
Versão do Editor: The original publication is available at: http://pubs.acs.org/journals/mamobx/index.html
Aparece nas colecções:DTQB - Artigos em Revistas Indexados ao ISI/Scopus

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