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Titolo:
ASYMMETRIC MARKOVIAN PROCESS IN THE POLYP ROPYLENE OBTAINED BY ZIEGLER-NATTA CATALYST WITH EXTERNAL ALKOXYSILANE DONORS
Autore:
CHUJO R; SAKAGUCHI E; HARKONEN M; SEPPALA JV;
Indirizzi:
NISHI TOKYO UNIV,DEPT MAT ENGN,2525 YATSUZAWA YAMANASHI 40901 JAPAN
Titolo Testata:
Kobunshi ronbunshu
fascicolo: 10, volume: 51, anno: 1994,
pagine: 647 - 651
SICI:
0386-2186(1994)51:10<647:AMPITP>2.0.ZU;2-X
Fonte:
ISI
Lingua:
JPN
Soggetto:
POLYMERIZATION; MODELS;
Keywords:
POLYPROPYLENE; ASYMMETRIC MARKOVIAN; EXTERNAL ALKOXYSILANE DONOR; TRIAD TACTICITY; FLUCTUATING SITE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
14
Recensione:
Indirizzi per estratti:
Citazione:
R. Chujo et al., "ASYMMETRIC MARKOVIAN PROCESS IN THE POLYP ROPYLENE OBTAINED BY ZIEGLER-NATTA CATALYST WITH EXTERNAL ALKOXYSILANE DONORS", Kobunshi ronbunshu, 51(10), 1994, pp. 647-651

Abstract

The formulae for conditional probabilities are derived with the termsof NMR triad tacticities for the polymers whose polymerization process is described by the asymmetric Markovian process. The obtained formulae are applied to the polypropylenes polymerized by Ziegler-Natta catalysts with external alkoxysilane donors. For both of unfractionated samples and heptane-insoluble fractions, the followings were clarified:1) on the transformation from symmtric to (fluctuating) asymmetric centers the transformation of one (hereafter, L) site is much enhanced than that of D site, 2) the monotonous increase of isotacticity as a result of the increase of the concentration of the donors is due to the increase of p(LL), 3) aromatic donors are effective than aliphatic ones for the improvement of isotacticity, and 4) the improvement of isotacticity after an addition of the alkoxysilanes is not due to the contribution from both of L and D sites, but the positive contribution fromthe former is larger than the negative one from the latter.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 14/08/20 alle ore 06:33:43