Synthesis and characterization of iPP‐sPP stereoblock produced by a binary metallocene system
2014; Wiley; Volume: 52; Issue: 10 Linguagem: Inglês
10.1002/pola.27127
ISSN1099-0518
AutoresCamille Descour, Tibor Macko, Dario Cavallo, Matthew Parkinson, Gerhard Hübner, Anne B. Spoelstra, Maurizio Villani, Robbert Duchateau,
Tópico(s)Polymer crystallization and properties
ResumoABSTRACT Stereoblock polypropylenes comprising of i PP and s PP segments are synthesized by polymerization of the following binary system of metallocenes: the C s ‐symmetric [2,7‐t‐Bu 2 (Flu) 2 Ph 2 C(Cp)ZrCl 2 ] and the C 2 ‐symmetric rac ‐Me 2 Si(2‐Me‐4‐Ph‐Ind) 2 ZrCl 2 . Blends of samples made either by each catalyst individually (solution blend) with materials obtained with the mixed catalyst system (reactor blend) are compared. The simultaneous presence of MAO and DEZ, enhancing fast and reversible transfer of the growing chains between the two active centers, leads to the formation of a stereoblock microstructure. In this case, low molecular weight polymers are obtained. The junction between the blocks is qualitatively observed in 13 C NMR. When made in toluene, the stereoblock material consists of a majority of syndiotactic sequences, whereas the ratio is more equilibrated when the polymerization was conducted in the more polar chlorobenzene. This is confirmed by the results obtained with 13 C NMR, CRYSTAF, HT HPLC, DSC, SSA, WAXD, and optical microscopy. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52 , 1422–1434
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