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Titolo:
LOW-TEMPERATURE EXCESS SPECIFIC-HEAT AND FRAGILITY IN POLYMERS - CRYSTALLINITY DEPENDENCE
Autore:
DANGELO G; TRIPODO G; CARINI G; BARTOLOTTA A; DIMARCO G; SALVATO G;
Indirizzi:
UNIV MESSINA,DIPARTIMENTO FIS,CONTRADA PAPARDO SALITA SPERONE 31 I-98166 MESSINA ITALY UNIV MESSINA,INFM I-98166 MESSINA ITALY CNR,IST TECN SPETTROSCOP I-98166 MESSINA ITALY
Titolo Testata:
The Journal of chemical physics
fascicolo: 17, volume: 109, anno: 1998,
pagine: 7625 - 7631
SICI:
0021-9606(1998)109:17<7625:LESAFI>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
THERMAL-CONDUCTIVITY; GLASS FORMERS; RELAXATION; POLYBUTADIENES; POLYETHYLENE; SCATTERING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
G. Dangelo et al., "LOW-TEMPERATURE EXCESS SPECIFIC-HEAT AND FRAGILITY IN POLYMERS - CRYSTALLINITY DEPENDENCE", The Journal of chemical physics, 109(17), 1998, pp. 7625-7631

Abstract

A study of the mechanical characteristics and the low-temperature specific heat has been performed on a class of polymers whose crystallinity degree varies in a wide range, from a wholly amorphous to a highly crystalline structure. Typical features of the amorphous phase have been analyzed in order to shed further light on their correlations: the deviation from the exponentiality and the ''fragility'' obtained by modeling the mechanical alpha(a)-relaxation and the excess specific heatover the predictions of the Debye theory. It has been found that increasing crystallinity enhances the nonexponentiality of the alpha(a)-relaxation, and decreases both the fragility and the excess specific heat. This behavior is intrinsic to semicrystalline polymers. Consequently, the recently suggested correlation between the degree of fragility and the additional law-energy vibrations causing the low-temperature excess specific heat in glasses fails in semicrystalline polymers. (C) 1998 American Institute of Physics. [S0021-9606(98)52340-9].

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Documento generato il 25/11/20 alle ore 09:40:24