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Titolo:
Influence of physical aging on the molecular motion and structural relaxation in poly(ethylene terephthalate) and related polyesters
Autore:
McGonigle, EA; Daly, JH; Jenkins, SD; Liggat, JJ; Pethrick, RA;
Indirizzi:
Univ Strathclyde, Dept Pure & Appl Chem, Glasgow G1 1XL, Lanark, Scotland Univ Strathclyde Glasgow Lanark Scotland G1 1XL G1 1XL, Lanark, Scotland Du Pont Polyester, Wilton Res Ctr, Middlesbrough TS90 8JE, Cleveland, England Du Pont Polyester Middlesbrough Cleveland England TS90 8JE eland, England
Titolo Testata:
MACROMOLECULES
fascicolo: 2, volume: 33, anno: 2000,
pagine: 480 - 489
SICI:
0024-9297(20000125)33:2<480:IOPAOT>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
POSITRON-ANNIHILATION LIFETIME; FREE-VOLUME; DIELECTRIC-RELAXATION; SEMICRYSTALLINE PEEK; BETA-RELAXATION; POLY(ETHYLENE-TEREPHTHALATE); POLYETHYLENETEREPHTHALATE; POLYMERS; CRYSTALLIZATION; COPOLYESTERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Liggat, JJ Univ Strathclyde, Dept Pure & Appl Chem, 295 Cathedral St, Glasgow G1 1XL,Lanark, Scotland Univ Strathclyde 295 Cathedral St Glasgow Lanark Scotland G1 1XL
Citazione:
E.A. McGonigle et al., "Influence of physical aging on the molecular motion and structural relaxation in poly(ethylene terephthalate) and related polyesters", MACROMOLEC, 33(2), 2000, pp. 480-489

Abstract

A combination of dielectric relaxation, dynamic mechanical thermal analysis, and positron annihilation measurements is reported on melt-cast films ofpoly(ethylene terephthalate), poly(ethylene naphthalate), and their copolymers. The effects of change in the chemical structure of the polyesters arerationalized in terms of increased restriction of the mobility of the polar segments of the chain by the incorporation of the bulky naphthalate structure. All the quenched samples exhibit physical aging when raised to elevated temperatures, the rate depending on the degree of undercooling used in the aging experiments. The free volume surprisingly does not change significantly with temperature and leads to the suggestion that the reduction in the dielectric permittivity is a consequence of a reduction in the mobility of the local segments. The increased storage modulus is also consistent witha reduction in mobility. This proposal is further confirmed by the observation of a good correlation between the rates and extents of the physical aging as detected by dynamic mechanical and dielectric relaxation measurements. Similarities in the activation energies of the beta relaxation process for all the polymers investigated indicate that the dipole relaxation processes have a common origin and can be ascribed to motion of the linking polarentity. This study implies that aging is accompanied by an increase in ordering within these polyesters.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 31/03/20 alle ore 19:39:07