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Titolo:
Differential scanning calorimetry, small-angle X-ray scattering, and wide-angle X-ray scattering on homogeneous and heterogeneous ethylene-alpha-copolymers
Autore:
Jokela, K; Vaananen, A; Torkkeli, M; Starck, P; Serimaa, R; Lofgren, B; Seppala, J;
Indirizzi:
Helsinki Univ Technol, Ctr Polymer Sci, FIN-02151 Espoo, Finland Helsinki Univ Technol Espoo Finland FIN-02151 , FIN-02151 Espoo, Finland Univ Helsinki, Dept Phys, Xray Lab, FIN-00014 Helsinki, Finland Univ Helsinki Helsinki Finland FIN-00014 ab, FIN-00014 Helsinki, Finland Helsinki Univ Technol, Dept Chem Technol, Lab Ind Chem & Polymer Technol, FIN-02015 HUT, Finland Helsinki Univ Technol HUT Finland FIN-02015 hnol, FIN-02015 HUT, Finland
Titolo Testata:
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
fascicolo: 16, volume: 39, anno: 2001,
pagine: 1860 - 1875
SICI:
0887-6266(20010815)39:16<1860:DSCSXS>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
LOW-DENSITY POLYETHYLENES; RISING ELUTION FRACTIONATION; THICKNESS DISTRIBUTIONS; LAMELLAR THICKNESS; CRYSTALLIZATION; DSC; MORPHOLOGY; 1-OCTENE; ETHENE; CRYSTALLINITY;
Keywords:
ethylene-alpha-copolymers; crystallization; lamellar thickness; differential scanning calorimetry (DSC); SAXS; WAXS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
52
Recensione:
Indirizzi per estratti:
Indirizzo: Starck, P Helsinki Univ Technol, Ctr Polymer Sci, Innopoli B2,POB 356, FIN-02151 Espoo, Finland Helsinki Univ Technol Innopoli B2,POB 356 Espoo Finland FIN-02151
Citazione:
K. Jokela et al., "Differential scanning calorimetry, small-angle X-ray scattering, and wide-angle X-ray scattering on homogeneous and heterogeneous ethylene-alpha-copolymers", J POL SC PP, 39(16), 2001, pp. 1860-1875

Abstract

The objective of this work was to use both X-ray and differential scanningcalorimetry techniques in a comparative study of the lamellar and crystalline structures of heterogeneous and homogeneous ethylene-a-copolymers. The samples differed in the comonomer type (1-butene, 1-hexene, 1-octene, and hexadecene), comonomer content, and catalyst used in the polymerizations. Step crystallizations were performed with differential scanning calorimetry, and the crystallinity and lamellar thicknesses of the different crystal populations were determined. Wide-angle X-ray scattering was used to determinecrystallinities, average sizes of the crystallites, and dimensions of the orthorhombic unit cell. The average thickness, separation of the lamellae, and volume fractions of the crystalline phase were determined by small-angle X-ray scattering (SAXS). The results revealed that at densities below 900kg/m(3), polymers were organized as poorly organized crystal bundles. The lamellar distances were smaller and the lamellar thickness distributions were narrower for the homogeneous ethylene copolymers than for the heterogeneous ones. Step-crystallization experiments by SAXS demonstrated that the long period increased after annealing. (C) 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1860-1875, 2001.

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Documento generato il 24/11/20 alle ore 10:36:00