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Titolo:
Parameters affecting the determination of transport kinetics data in highly swelling polymers above T-g
Autore:
Hedenqvist, MS; Gedde, UW;
Indirizzi:
Royal Inst Technol, Dept Polymer Technol, S-10044 Stockholm, Sweden Royal Inst Technol Stockholm Sweden S-10044 l, S-10044 Stockholm, Sweden Packforsk Swedish Packaging Res Inst, S-16493 Kista, Sweden Packforsk Swedish Packaging Res Inst Kista Sweden S-16493 Kista, Sweden
Titolo Testata:
POLYMER
fascicolo: 9, volume: 40, anno: 1999,
pagine: 2381 - 2393
SICI:
0032-3861(199904)40:9<2381:PATDOT>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOLVENT DIFFUSION; ANOMALOUS DIFFUSION; GLASSY-POLYMERS; POLYETHYLENE; SORPTION; LIQUID;
Keywords:
S-shaped sorption curves; highly swollen polymers; transport kinetics;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
34
Recensione:
Indirizzi per estratti:
Indirizzo: Gedde, UW Royal Inst Technol, Dept Polymer Technol, S-10044 Stockholm, Sweden Royal Inst Technol Stockholm Sweden S-10044 Stockholm, Sweden
Citazione:
M.S. Hedenqvist e U.W. Gedde, "Parameters affecting the determination of transport kinetics data in highly swelling polymers above T-g", POLYMER, 40(9), 1999, pp. 2381-2393

Abstract

Sorption and desorption data for n-hexane-natural rubber and n-hexane-low-density polyethylene were analysed to reveal the cause of the s-shaped sorption curves frequently occurring in highly swollen polymers. The model permitted the influence of solute-concentration-dependent diffusivity, sample geometry, boundary concentrations and swelling-induced mechanical stresses on the transport data to be examined. The calculated solute diffusivity varied by several orders of magnitude, depending on the choice of parameters included in the model. The inclusion of direct mechanical stress relaxation parameters only gave a slight improvement of the fit to the experimental data. The inclusion of a time-dependent surface concentration was the only wayto fit the a-shaped sorption curves for both natural rubber and low-density polyethylene. Although isotropic three-dimensional swelling of natural rubber occurred over the whole sorption transient period, this condition was unable to explain the swelling (thickness increase) of low-density polyethylene. In the latter system, a model consisting of two stages had to be adopted: stage I where the swelling was mainly one-dimensional, and stage II which occurred later and was characterized by three-dimensional swelling similar to that occurring in natural rubber. During the transient sorption period, the ratio between natural rubber and low-density polyethylene of the ratio of the thickness to cross-sectional area was close to their bulk modulus ratio, which suggests that it is the bulk modulus rather than the Young'smodulus which determines the sorption characteristics of polymers above T-g. (C) 1999 Elsevier Science Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/01/21 alle ore 14:39:39