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Influence of branching on melting behavior and isothermal crystallization of poly(butylene terephthalate)
Author(s) -
Righetti Maria Cristina,
Munari Andrea
Publication year - 1997
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1997.021980212
Subject(s) - branching (polymer chemistry) , crystallization , nucleation , differential scanning calorimetry , isothermal process , materials science , polymer chemistry , thermodynamics , melting point , kinetics , chemical engineering , composite material , physics , quantum mechanics , engineering
The melting behavior and the isothermal crystallization kinetics of linear and randomly branched poly(butylene terephthalate) System. name: poly(tetramethylene terephthalate). (PBT) samples were investigated by differential scanning calorimetry. The multiple endotherms typical of linear PBT were observed also in branched samples and were found to be influenced both by temperature and degree of branching. The isothermal crystallization kinetic constants, obtained applying Avrami's treatment, were analysed on the basis of Hoffman's secondary nucleation theory. A decrease in the crystallization rate was observed as the content of branching units increased. This result was correlated to surface effects: the product of the surface free energies σσ e was found to increase with the ramification content. As far as the nucleation process is concerned, the induction time was determined for all the samples at different crystallization temperatures, and the results suggested that in the presence of branching points the nucleation process is favoured.