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Titolo:
MOLECULAR MOBILITY IN SEMI-IPNS OF LINEAR POLYURETHANE AND HETEROCYCLIC POLYMER NETWORKS
Autore:
BARTOLOTTA A; DIMARCO G; LANZA M; CARINI G; DANGELO G; TRIPODO G; FAINLEIB A; SLINCHENKO EA; PRIVALKO VP;
Indirizzi:
UNIV MESSINA,DIPARTIMENTO FIS,CONTRADA PAPARDO,SALITA SPERONE 31 I-98166 SANT AGATA ME ITALY UNIV MESSINA,DIPARTIMENTO FIS I-98166 SANT AGATA ME ITALY CNR,IST TECN SPETTROSCOP I-98166 SANT AGATA ME ITALY UNIV MESSINA,INFM I-98166 SANT AGATA ME ITALY NATL ACAD SCI UKRAINE,INST MACROMOL CHEM UA-253160 KIEV UKRAINE
Titolo Testata:
The Journal of adhesion
fascicolo: 1-4, volume: 64, anno: 1997,
pagine: 269 - 286
SICI:
0021-8464(1997)64:1-4<269:MMISOL>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
RELAXATION;
Keywords:
ANELASTICITY; INTERNAL FRICTION; ANHARMONICITY; GLASS TRANSITION; POLYMERS; CROSS-LINKED TRIMERIZED CYANATE; PRIMARY AND SECONDARY RELAXATIONS; THERMO MECHANICAL PROPERTIES;
Tipo documento:
Article
Natura:
Periodico
Citazioni:
9
Recensione:
Indirizzi per estratti:
Citazione:
A. Bartolotta et al., "MOLECULAR MOBILITY IN SEMI-IPNS OF LINEAR POLYURETHANE AND HETEROCYCLIC POLYMER NETWORKS", The Journal of adhesion, 64(1-4), 1997, pp. 269-286

Abstract

A study of the thermal and mechanical properties of new semi-interpenetrating polymer networks (IPN's) based on linear polyurethane (PU) and crosslinked trimerized dicyanate (TDC) reveals the existence of structures characterized by the absence of chemical interactions. Two distinct glass transitions are observed in the thermograms, as an indication of the fact that the two polymeric components preserve their molecular structure. The interpenetration affects markedly the glass transition temperatures revealed in the pure components in consequence of modifications in the local environments of the relaxing molecular units in the two phases. The primary and secondary relaxations of these systems show features which can be explained by accounting for the free-volume decrease due to the inclusion of PU in the network of TDC. Below the glass transition two molecular relaxations have been observed whichhave bean ascribed to the secondary relaxation motions characterizingeach polymeric component. Both relaxations exhibit a marked non-exponentiality which has been well accounted for in terms of a Gaussian distribution of relaxation times. The results of this analysis suggest that the local motions of TDC, ascribed to phenylene groups in the crosslinks between the cyanate units, are severely restricted by the inclusion of PU, while those of PU are slightly influenced by the presence of TDC.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/12/20 alle ore 18:26:54