Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Free volume-size dependence on temperature and average molecular-weight inpoly(ethylene oxide) determined by positron annihilation lifetime spectroscopy
Autore:
Porto, AO; Silva, CG; Magalhaes, WF;
Indirizzi:
Univ Fed Minas Gerais, LEAP, Positron Annihilat Spect Lab, BR-31270901 Belo Univ Fed Minas Gerais Belo Horizonte MG Brazil BR-31270901 BC1270901 Belo Univonte,Minas Gerais, ICEx, Dept Chem, Mat Sci Lab, BR-31270901 Belo Horiz Univ Fed Minas Gerais Belo Horizonte MG Brazil BR-31270901 BC1 Belo Horiz
Titolo Testata:
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
fascicolo: 3, volume: 37, anno: 1999,
pagine: 219 - 226
SICI:
0887-6266(19990201)37:3<219:FVDOTA>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
LIQUID-GLASS TRANSITION; AMORPHOUS POLYMERS; POLYSTYRENE; PROBE; PARAMETERS; PEEK;
Keywords:
positron annihilation lifetime spectroscopy; DSC; poly(ethylene oxide);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Magalhaes, WF Univ901d Minas Gerais, LEAP, Positron Annihilat Spect Lab, CP 702, BR-31270 Univ Fed Minas Gerais CP 702 Belo Horizonte MG Brazil BR-31270901 BC
Citazione:
A.O. Porto et al., "Free volume-size dependence on temperature and average molecular-weight inpoly(ethylene oxide) determined by positron annihilation lifetime spectroscopy", J POL SC PP, 37(3), 1999, pp. 219-226

Abstract

Positron lifetime measurements were carried out in a series of poly(ethylene oxide)-PEO-of different average molecular weights ((M) over bar(w)): 1000, 1500, 6000, 10,000, 300,000, and 4 M. The mean radius ((R) over bar) andthe mean free volume size (Vf) values were determined using a semiempirical equation that correlates the orthopositronium (o-Ps) lifetime (tau(3)) and size of holes existing in the amorphous phases. The hole mean radius values determined at room temperature from lifetime spectra were found to be between 2.68 and 2.97 Angstrom, and the hole volumes between 80 and 110 Angstrom(3). Free volume size evolution was studied with temperature variation until the melting temperature of the PEO samples. The degree of crystallinity and the melting temperatures were determined by Differential Scanning Calorimetry. (C) 1999 John Wiley & Sons, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/03/20 alle ore 00:01:36