Elastomeric polypropylenes from alumina-supported tetraalkyl group IVB catalysts. 2. Chain microstructure, crystallinity, and morphology

Collette, John W.; Ovenall, Derick W.; Buck, Warren H.; Ferguson, Raymond C.

doi:10.1021/ma00200a007

Cited by 97 publications

(105 citation statements)

References 6 publications

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“…In this direction, one cell contains 3 monomers [35]. result is in good agreement with the previous estimate of 14 for the length of the shortest crystallisable isotactic sequence [36,37].…”

Section: Isotactic Sequence Lengthssupporting

confidence: 91%

Tacticity distribution of isotactic polypropylene prepared with heterogeneous Ziegler–Natta catalyst. 2. Application and analysis of SSA data for polypropylene

Virkkunen

Laari

Pitkänen

et al. 2004

Polymer

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Section: Isotactic Sequence Lengthssupporting

confidence: 91%

Tacticity distribution of isotactic polypropylene prepared with heterogeneous Ziegler–Natta catalyst. 2. Application and analysis of SSA data for polypropylene

Virkkunen

Laari

Pitkänen

et al. 2004

Polymer

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“…Polymerizations were conducted in a 1 l autoclave (previously cleaned with a 0.5 mol-% solution of Al(i-butyl) 3 in toluene and dried in vacuo) filled with 350 ml of purified toluene, using a solution of 6.15 lmol of precursor 1 -3, or 0.4 lmol of 4, followed by the addition of 0.45 g of methylaluminoxane (Witco AG, molecular weight ca. 900) in toluene at the corresponding temperature and a constant propylene pressure.…”

Section: Polymerization Proceduresmentioning

confidence: 99%

Synthesis and properties of elastomeric poly(propylene)

Mansel

Pérez²,

Benavente

et al. 1999

Macromol. Chem. Phys.

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SUMMARY: Elastomeric poly(propylene) with low percentages of isotactic pentads and high molecular weight was synthesized using unbridged "oscillating" metallocenes. The polymer sample with the highest [mmmm] content (22%) shows a small amount of crystallinity, which is highly influenced by the thermal history, and differs significantly in stress-strain and dynamic mechanical properties from all other samples. Polymers with lower isotacticity index, although lacking crystallinity in thermal analysis, differ in their viscoelastic behaviour from those of atactic poly(propylene). In dynamic mechanical analysis the c relaxation at low temperature shows high sensitivity to low isotactic contents.

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“…[2] Single component TPEs can be prepared through propylene polymerization with both homogeneous [3,4] and heterogeneous organometallic catalysts. [5] The elastic properties of elastomeric poly(propylene)s are believed to arise from their stereo-block (isotactic-atactic) microstructure [3][4][5][6] that allows the formation of short crystallizable isotactic blocks in a low (overall) tacticity polymer chain.…”

Section: Introductionmentioning

confidence: 99%

Molecular Weight and Long Chain Branch Distributions of Branch‐Block Olefinic Thermoplastic Elastomers

Nele

Soares

2003

Macro Theory & Simulations

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Olefinic thermoplastic elastomers can be prepared by incorporating semi‐crystalline macromonomers (e.g. isotactic or syndiotactic poly(propylene), high‐density polyethylene) onto amorphous backbones (e.g. atactic poly(propylene), ethylene/α‐olefin copolymers). The macromonomer incorporation reaction can be carried out in semi‐batch reactors by adding previously synthesized macromonomers to the reactor (ex situ approach), or by generating and incorporating the macromonomers in a single step (in situ approach). The differences in the microstructure of copolymers synthesized by in situ and ex situ techniques are explored herein through a mathematical model that can predict the concentration of linear and branched chains, their average molecular weights, polydispersity indices, and molecular weight distributions. In both cases linear chains predominate, but the ex situ approach produces a larger amount of branched chains with thermoplastic elastomer properties. Furthermore, for the in situ strategy, a significant amount of branched chains is only formed after the macromonomer concentration reaches a critical value.Schematic representation of the polymerization mechanism.imageSchematic representation of the polymerization mechanism.

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Elastomeric polypropylenes from alumina-supported tetraalkyl group IVB catalysts. 2. Chain microstructure, crystallinity, and morphology

Cited by 97 publications

References 6 publications

Tacticity distribution of isotactic polypropylene prepared with heterogeneous Ziegler–Natta catalyst. 2. Application and analysis of SSA data for polypropylene

Tacticity distribution of isotactic polypropylene prepared with heterogeneous Ziegler–Natta catalyst. 2. Application and analysis of SSA data for polypropylene

Synthesis and properties of elastomeric poly(propylene)

Molecular Weight and Long Chain Branch Distributions of Branch‐Block Olefinic Thermoplastic Elastomers

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