Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Effect of physical aging of poly(1-trimethylsilyl-1-propyne) films synthesized with TaCl5 and NbCl5 on gas permeability, fractional free volume, and positron annihilation lifetime spectroscopy parameters
Autore:
Nagai, K; Freeman, BD; Hill, AJ;
Indirizzi:
N Carolina State Univ, Dept Chem Engn, Raleigh, NC 27606 USA N Carolina State Univ Raleigh NC USA 27606 em Engn, Raleigh, NC 27606 USA CSIRO, Clayton S, MDC 3169, Australia CSIRO Clayton S MDC Australia 3169CSIRO, Clayton S, MDC 3169, Australia Monash Univ, Dept Chem, Clayton, Vic 3168, Australia Monash Univ Clayton Vic Australia 3168 Chem, Clayton, Vic 3168, Australia
Titolo Testata:
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
fascicolo: 9, volume: 38, anno: 2000,
pagine: 1222 - 1239
SICI:
0887-6266(20000501)38:9<1222:EOPAOP>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
TEMPERATURE-DEPENDENCE; MEMBRANES; POLYMERS; SOLUBILITY; SEPARATION; POLY<1-(TRIMETHYLSILYL)-1-PROPYNE>; 1-(TRIMETHYLSILYL)-1-PROPYNE; POLYACETYLENES; DIFFUSIVITY; PERMEATION;
Keywords:
poly(1-trimethylsilyl-1-propyne); aging; gas permeability; positron annihilation lifetime spectroscopy; fractional free volume;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Freeman, BD N Carolina State Univ, Dept Chem Engn, Raleigh, NC 27606 USA NCarolina State Univ Raleigh NC USA 27606 eigh, NC 27606 USA
Citazione:
K. Nagai et al., "Effect of physical aging of poly(1-trimethylsilyl-1-propyne) films synthesized with TaCl5 and NbCl5 on gas permeability, fractional free volume, and positron annihilation lifetime spectroscopy parameters", J POL SC PP, 38(9), 2000, pp. 1222-1239

Abstract

The effect of physical aging on the gas permeability, fractional free volume (FFV), and positron annihilation lifetime spectroscopy (PALS) parametersof dense, isotropic poly(1-trimethylsilyl-1propyne) (PTMSP) films synthesized with TaCl5 and NbCl5 was characterized. As-cast films were soaked in methanol until an equilibrium amount of methanol was absorbed by the polymer. When the films were removed from methanol. film thickness initially decreased rapidly and was almost constant after 70 h in air for both catalysts. This timescale was much longer than the timescale for complete methanol desorption (ca. 5 h). From the film-thickness data. the reduction in FFV with time was estimated. For samples prepared with either catalyst, the kinetics of FFV reduction were well-described by a simple model based on the notion either that free-volume elements diffuse to the surface of the polymer filmand are subsequently eliminated from the sample or that lattice contraction controls polymer densification. Methane permeability decreased rapidly during the first 70 h? which was the same timescale for the thickness change. The decrease in methane permeability was smaller in films prepared with NbCl5 than with TaCl5. The logarithm of methane permeability decreased linearly as reciprocal FFV increased, in accordance with free-volume theory. The PALS results indicate that the concentration of larger free-volume elements(as indicated by the intensity I-4) decreased with aging time and that theother PALS parameters were not strongly influenced by aging. (C) 2000 JohnWiley & Sons, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/04/20 alle ore 13:36:23