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Titolo:
Molar mass distribution of linear and branched polyurethane studied by size exclusion chromatography
Autore:
Prochazka, F; Nicolai, T; Durand, D;
Indirizzi:
Univ Maine, UMR CNRS, F-72085 Le Mans 9, France Univ Maine Le Mans France 9 v Maine, UMR CNRS, F-72085 Le Mans 9, France
Titolo Testata:
MACROMOLECULES
fascicolo: 5, volume: 33, anno: 2000,
pagine: 1703 - 1709
SICI:
0024-9297(20000307)33:5<1703:MMDOLA>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
SCALING PROPERTIES; LIGHT-SCATTERING; GEL POINT; POLYESTERS; GELATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Nicolai, T Univ Maine, UMR CNRS, F-72085 Le Mans 9, France Univ Maine Le Mans France 9 R CNRS, F-72085 Le Mans 9, France
Citazione:
F. Prochazka et al., "Molar mass distribution of linear and branched polyurethane studied by size exclusion chromatography", MACROMOLEC, 33(5), 2000, pp. 1703-1709

Abstract

Linear polyoxypropylene (POP) diol and star POP triol were end linked using diisocyanate. Linear and branched polyurethanes (PU) of varying size wereformed by varying the stoichiometric ratio r of isocyanate and hydroxyl groups. End-Linked POP triol forms a gel for r > 0.55. Molar mass distributions of linear and soluble branched PU were determined using size exclusion chromatography as a function of r in the range 0-1. The fractions of the first few oligomers at different r are in good agreement with calculated values using mean field theory. Branched POP triol has a very broad molar mass distribution close to the gel point. At low degree of polymerization (DP < 10) the molar mass distribution is well described by mean field theory whilefor DP > 300 it is better described by the percolation model. The results imply that many earlier measurements on gel-forming systems reported in theliterature were done on samples in the crossover regime.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/07/20 alle ore 16:15:36