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Titolo:
FREE-VOLUME MICROSTRUCTURE AND ITS RELATIONSHIP TO THE CHAIN DYNAMICSIN CIS-1,4-POLY(BUTADIENE) AS SEEN BY POSITRON-ANNIHILATION LIFETIME SPECTROSCOPY
Autore:
BARTOS J; BANDZUCH P; SAUSA O; KRISTIAKOVA K; KRISTIAK J; KANAYA T; JENNINGER W;
Indirizzi:
SLOVAK ACAD SCI,INST POLYMER SK-84236 BRATISLAVA SLOVAKIA SLOVAK ACAD SCI,INST PHYS SK-84228 BRATISLAVA SLOVAKIA KYOTO UNIV,INST CHEM RES UJI 611 JAPAN DEUTSCH KUNSTSTOFF INST DARMSTADT D-64289 DARMSTADT GERMANY
Titolo Testata:
Macromolecules
fascicolo: 22, volume: 30, anno: 1997,
pagine: 6906 - 6912
SICI:
0024-9297(1997)30:22<6906:FMAIRT>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUMERICAL LAPLACE INVERSION; HOLE SIZE DISTRIBUTION; CURED EPOXY POLYMERS; GLASS-TRANSITION; AMORPHOUS POLYMERS; PRESSURE-DEPENDENCE; MOLECULAR-DYNAMICS; CIS-1,4-POLYBUTADIENE; POLYBUTADIENES; TEMPERATURES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
65
Recensione:
Indirizzi per estratti:
Citazione:
J. Bartos et al., "FREE-VOLUME MICROSTRUCTURE AND ITS RELATIONSHIP TO THE CHAIN DYNAMICSIN CIS-1,4-POLY(BUTADIENE) AS SEEN BY POSITRON-ANNIHILATION LIFETIME SPECTROSCOPY", Macromolecules, 30(22), 1997, pp. 6906-6912

Abstract

The annihilation characteristics of the orthopositronium (o-Ps) in the structurally simplest elastomer cis-1,4-poly(butadiene) has been measured in the temperature range from 15 to 313 K and interpreted in theframework of the free volume concept. The temperature dependence of the mean lifetime of the o-Ps, tau(3), and its relative intensity, I-3,reflect a fine interplay between the free volume and microscopic chain dynamics. In addition to a pronounced break on the tau(3)-T plot at the glass transition temperature, T-g, a further two bends exist. The first, in glassy state, is relatively slight. The other one, in an elastic state, can be correlated with the melting temperature T-m of the crystalline phase. The order agreement between the temperature coefficients of free volume hole expansion a(h) and the mean square displacement of chain atoms alpha a(()[u2](>) from a recent neutron scattering study indicates a microscopic cause for the hole size growth with temperature. The decrease of I-3 with temperature T above 120 K correlateswith the onset temperature of the so-called fast motion from neutron scattering measurements as well as with the so called Vogel temperature T-o for the primary segmental dynamics. The N-like shape course above T-g correlates with the cold crystallization from DSC measurements. In the melt region above 265 K, the slightly dependent tau(3) and I-3 quantities correspond to a formation of the bubble states of the o-Ps in the soft matrix. Finally, the temperature dependence of free volumehole distributions exhibits the essential changes from relative narrow distributions in the glassy state to wide distributions above T-g and ones that do not change much in the melt region of the polymer matrix.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/07/20 alle ore 18:40:20