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Titolo:
RHEOLOGICAL PROPERTIES OF A PARTIALLY MOLTEN POLYPROPYLENE RANDOM COPOLYMER DURING ANNEALING
Autore:
HINGMANN R; RIEGER J; KERSTING M;
Indirizzi:
BASF AG,DIV POLYMER RES D-67056 LUDWIGSHAFEN GERMANY
Titolo Testata:
Macromolecules
fascicolo: 11, volume: 28, anno: 1995,
pagine: 3801 - 3806
SICI:
0024-9297(1995)28:11<3801:RPOAPM>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
CRYSTALLIZATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
16
Recensione:
Indirizzi per estratti:
Citazione:
R. Hingmann et al., "RHEOLOGICAL PROPERTIES OF A PARTIALLY MOLTEN POLYPROPYLENE RANDOM COPOLYMER DURING ANNEALING", Macromolecules, 28(11), 1995, pp. 3801-3806

Abstract

Semicrystalline polymers exhibit a broad melting transition. This effect is due to the lamellar thickness distribution in the materials. The melting temperature T-m(l) of a given lamella increases with its thickness l. When heating to a temperature T-a in the melting range, the crystalline lamellae with T-m(l) < T-a belt. This process is accompanied by the thickening of the nonmolten lamellae which suck in molten polymer chains. We used a polypropylene random copolymer as a convenientmaterial to investigate theological and structural aspects of this reorganizational process. The temperature and time dependence of the dynamic moduli G' and G'' in oscillatory shear flow and for the first time of the transient uniaxial elongational viscosity were measured during the reorganization of the partially molten material. Data from differential scanning calorimetry (DSC) runs on the annealed samples are correlated with the respective data from the theological experiments. With increasing amount of crystalline material the shear viscosity function increases at small shear rates. At the same time marked strain hardening shows up in uniaxial elongation. The theological phenomena observed during annealing at temperatures in the melting range are interpreted by assuming a network of nonmolten, growing lamellae which are connected by tie chains.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/07/20 alle ore 18:04:25