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Titolo:
Influence of intermolecular entanglements on the glass transition and structural relaxation behaviors of macromolecules. 2. Polystyrene and phenolphthalein poly(ether sulfone)
Autore:
Huang, DH; Yang, YM; Zhuang, GQ; Li, BY;
Indirizzi:
Chinese Acad Sci, Changchun Inst Appl Chem, Changchun 130022, Peoples R China Chinese Acad Sci Changchun Peoples R China 130022 30022, Peoples R China
Titolo Testata:
MACROMOLECULES
fascicolo: 2, volume: 33, anno: 2000,
pagine: 461 - 464
SICI:
0024-9297(20000125)33:2<461:IOIEOT>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
DRIED ATACTIC POLYSTYRENE; DILUTE-SOLUTIONS; CONCENTRATION-DEPENDENCE; ISOTACTIC POLYSTYRENE; ENTHALPY RELAXATION; CRYSTALLIZATION; POLYMERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
18
Recensione:
Indirizzi per estratti:
Indirizzo: Huang, DH Chinese Acad Sci, Changchun Inst Appl Chem, Changchun 130022, Peoples R China Chinese Acad Sci Changchun Peoples R China 130022 ples R China
Citazione:
D.H. Huang et al., "Influence of intermolecular entanglements on the glass transition and structural relaxation behaviors of macromolecules. 2. Polystyrene and phenolphthalein poly(ether sulfone)", MACROMOLEC, 33(2), 2000, pp. 461-464

Abstract

The effect of entanglements on the glass transition and structural relaxation behaviors has been studied for polystyrene (PS) and phenolphthalein poly(ether sulfone) (PES-C) samples by fast evaporation of the solution of concentrations varying from above the overlapping concentration to far below it, and compared to the results we have studied previously in PC. It has been found that for all the polymers we have studied, in the concentrated solution region, the T-g of the samples obtained from solution are independent of the change of concentration and are very close to that of normal bulk samples, whereas in the dilute solution region the T-g of the samples decrease with the logarithm of decreasing concentration. The critical concentrations that divide the two distinct regions for the three polymers are 0.9% g/mL for PC, 0.1% g/mL for PS, and 1% g/mL for PES-C. The decrease of T-g of the samples is interpreted by the decrease of intermolecular entanglements as the isolation of polymer chains, and the entanglement of polymer chains restrained the mobility of the segments. The structural relaxation behavior of the polymers is also found to be different from that of normal bulk samples. The enthalpies of single-chain samples are lower than that of the bulkones, which correspond to the lower glass transition temperature; the peaks are lower and broader, and the relaxed enthalpy is much lower as comparedto that of bulk samples. In the three polymers we have studied, the influence of change of entanglements on both the decrease in glass transition temperature and relaxed enthalpy is the most significant for PS and the least for PES-C. It is indicated that the interactions in the flexible polymers are weak; thus, the restraint of the entanglements on the mobility of the segments plays a more important role in the flexible polymers, and the changeof entanglement in the flexible polymers has a more significant influence on the physical properties.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 09:42:18