Publicação
Lewis acid/base character and crystallisation properties ofpoly(butylene terephthalate)
| Resumo: | Two grades of poly(butylene terephthalate) were analysed by means of inverse gas chromatography(IGC) and the results correlated with the respective crystallisation properties. The following parameterswere determined by IGC: the dispersive component of the surface tension, the enthalpy and the entropyof adsorption of selected polar and apolar probes, and the Lewis acidity and basicity constants, KaandKbrespectively. The interpretation of the values determined for Kaand Kbis in agreement with the FTIRspectra relating to the carboxyl end-group and the hydroxyl end-group concentrations in these polymers.The differences in the molecular weight values and in the end-group type and concentration, betweenthe two grades of PBT, do not cause differences in the crystallisation activation energy. This observationsuggests that there is a leading contribution of the Lewis basic sites to the crystallisation activation energyof the grades of PBT that were analysed. However, the lower value of Kaand the greater molar mass ofone of the PBT grades lead to a corresponding lower crystallisation degree. |
|---|---|
| Autores principais: | Santos, José M.R.C.A. |
| Outros Autores: | Guthrie, James T. |
| Assunto: | Inverse gas chromatography Poly(butylene terephthalate) Lewis acid/base properties Crystallisation |
| Ano: | 2015 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | Two grades of poly(butylene terephthalate) were analysed by means of inverse gas chromatography(IGC) and the results correlated with the respective crystallisation properties. The following parameterswere determined by IGC: the dispersive component of the surface tension, the enthalpy and the entropyof adsorption of selected polar and apolar probes, and the Lewis acidity and basicity constants, KaandKbrespectively. The interpretation of the values determined for Kaand Kbis in agreement with the FTIRspectra relating to the carboxyl end-group and the hydroxyl end-group concentrations in these polymers.The differences in the molecular weight values and in the end-group type and concentration, betweenthe two grades of PBT, do not cause differences in the crystallisation activation energy. This observationsuggests that there is a leading contribution of the Lewis basic sites to the crystallisation activation energyof the grades of PBT that were analysed. However, the lower value of Kaand the greater molar mass ofone of the PBT grades lead to a corresponding lower crystallisation degree. |
|---|