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