Synthesis of polypropene‐block‐poly(ethylene‐co‐propene) by short‐period polymerization with MgCl2‐supported Ziegler catalyst

Mori, Hideharu; Yamahiro, Mikio; Tashino, Kunihiko; Ohnishi, Kouki; Nitta, K.; Terano, Minoru

doi:10.1002/marc.1995.030160403

Cited by 21 publications

(23 citation statements)

References 8 publications

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“…Details of the polymerization procedure were shown in the previous paper. 1 The molecular characteristics of the polymers used in this study are summarized in Table I. The molecular weight and its distribution were determined using a high-temperature GPC instrument (Senshu SSC-7100) with o-dichlorobenzene (ODCB) as a solvent at 413 K. The ethylene content in the samples was determined by 13 C-NMR spectra using a Varian Gemini-300 spectrometer.…”

Section: Experimental Materialsmentioning

confidence: 99%

“…In a previous paper, 1 we demonstrated the possibility of preparing diblock copolymers of isotactic polypropylene (designated as PP) and ethylenepropylene random copolymer (designated as EPR) with a short-period polymerization method. It was determined that the short-period (or stoppedflow) polymerization makes it possible to perform "quasiliving polymerization" during a very short period (up to about 0.2 s) in such a way of avoiding chain-transfer reactions.…”

Section: Introductionmentioning

confidence: 99%

“…It was determined that the short-period (or stoppedflow) polymerization makes it possible to perform "quasiliving polymerization" during a very short period (up to about 0.2 s) in such a way of avoiding chain-transfer reactions. [2][3][4] The formation of a block structure, in which EPR is chemically linked with PP, has been suggested from the experimental facts 1 that molecular distribution curves in gel-permeation chromatography (GPC) are unimodal and the EPR component exists on 13 C-NMR spectra after extraction with heptane.…”

Section: Introductionmentioning

confidence: 99%

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Characterization and properties of polypropylene-block-poly(ethylene-co-propylene) synthesized by short-period polymerization

Nitta

Kawada

Прохоров

et al. 1999

J. Appl. Polym. Sci.

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ABSTRACT:The morphology and mechanical properties of novel block copolymers consisting of isotactic polypropylene (PP) and ethylene-propylene rubber (EPR) synthesized by a short-period polymerization method were examined using differential scanning calorimetry, atomic force microscopy, dynamic mechanical analysis, and a rheooptical technique. It was found that the novel block copolymers show a single glass transition and EPR segments are trapped into the amorphous region of PP. Furthermore, the rheooptical analysis demonstrates that a drawing process of the EPR-rich block copolymer induces orientation of the PP lamellae in the EPR matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 958 -964, 1999

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Section: Experimental Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization and properties of polypropylene-block-poly(ethylene-co-propylene) synthesized by short-period polymerization

Nitta

Kawada

Прохоров

et al. 1999

J. Appl. Polym. Sci.

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“…The activity of the catalyst was constant without deactivation in this region. Thus, the modified stopped-flow apparatus was successfully applied to synthesize polypropene-block-poly(ethyleneco-polypropene), in which poly(ethene-co-propene) was chemically linked with polypropene [1][2][3][4][5] .…”

Section: Introductionmentioning

confidence: 99%

Lifetime of growing polymer chain in stopped-flow propene polymerization using pre-treated Ziegler catalysts

Mori

Yamahiro

Terano³

et al. 2000

Macromol. Chem. Phys.

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The lifetime of a growing polymer chain of monoester‐type and diester‐type supported catalysts was investigated by the stopped‐flow polymerization technique. A linear correlation of the polymerization time with both the polymer yield and the molecular weight was observed for the monoester‐type supported catalyst until a certain time period (0.2 s), where the growing polymer chain is still active. The activity of the diester‐type supported catalyst was found to increase gradually throughout the polymerization (0–1.2 s). The polymer yield and the molecular weight are proportional to time up to 1.2 s when the pre‐treatment of the diester‐type supported catalyst was conducted with triethylaluminium. The active sites on the pre‐treated catalyst exert a longer lifetime (at least 1.2 s) compared with that on the monoester‐type and diester‐type supported catalysts without pre‐treatment. Kinetic studies indicated that the pre‐treatment influences not only the number of active sites, but also the ratio of isospecific active sites to aspecific ones formed on the supported catalyst.

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“…In addition, the copolymerization of iPP with EPR, instead of their mixing, has been also explored and considered as an effective way to attain high-impact iPP. 36,37 Thermal treatment is primarily responsible for the development of a particular structure in an iPP homopolymer and, by extrapolation, for the properties exhibited. However, it is not very common in the literature to find a detailed study of the crystalline structure and properties together, being considerably more scarce the papers related, even exclusively, to the properties presented by the mesomorphic iPP.…”

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confidence: 99%

Structure and Mechanical Behavior of the Mesomorphic Form in a Propylene-b-Poly(ethylene-co-propylene) Copolymer and Its Comparison with Other Thermal Treatments

Arranz-Andrés

Benavente

Pérez

et al. 2003

Polym J

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ABSTRACT:Several thermal treatments have been imposed along processing to a poly[propylene-b-(ethylene-copropylene)] and their effect on structure, thermal characterization and mechanical response has been explored. Quenching in a dry ice/methanol bath after melting has allowed to obtain a mesomorphic form due to the existence of long isotactic polypropylene (iPP) chains within the block copolymer here studied. An exhaustive analysis of such a mesophase has been performed comparing its morphological details and mechanical properties with the rest of thermal treatments. A microspherulitic superstructure is found in this mesomorphic form which leads to the lowest values in mechanical parameters, such as storage and Young moduli as well as microhardness, compared to those exhibited by the other specimens with distinct thermal histories. However, the ductility of the mesomorphic structure is the highest one, owed to the non-existence of monoclinic crystallites. A phase transition is observed at around 90• C on heating, which suggests the transformation of this mesomorphic form to the monoclinic crystalline structure. KEY WORDS Poly(ethylene-co-propylene) / Mesomorphic Form / Monoclinic Crystallites /The crystallization behavior of isotactic polypropylene (iPP) is very complicated. The morphology and properties after crystallization depend upon thermal history and the detailed microstrucutre of the polymer molecules. The iPP chains adopt a 3 1 helical conformation when crystallized from the molten state. These helical chains can organize into several different spatial arrangements giving rise to three distinct polymorphs: α-monoclinic, β-hexagonal, and γ-orthorhombic forms, depending on the crystallization conditions and catalyst used. [1][2][3][4][5][6][7][8][9][10][11][12][13] Cooling from the melt at low or moderate cooling rates leads usually to the formation of the thermodynamically stable α-monoclinic crystalline lattice, being this α-form the most common one.Moreover, there is also a "mesomorphic" phase, which can be obtained by rapid quenching of molten iPP. The appearance of two broad peaks in the X-ray diffraction pattern is a characteristic of this quenched form. 14 The presence of broad, diffuse peaks in X-ray diffraction tends to suggest that the quenched structure is in a disorder state. These two peaks, however, exhibit an intermediate width between the crystal diffractions and the pattern found for a completely amorphous polypropylene. 15 Natta and Corradini 1 first pointed out that this form had an intermediate degree of ordering between the amorphous phase and the crystalline phase. They categorized it as smectic to indicate the presence of two-dimensional ordering, being better in longitudinal than in transverse chain direction. 16 However, the full evidence for the smectic phase in iPP has not been documented. The description of the mesophase can be quite confusing in the literature. In addition to the smectic phase, 1, 17 other investigators described the mesomorphic phase as paracrystalline, 18...

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Synthesis of polypropene‐block‐poly(ethylene‐co‐propene) by short‐period polymerization with MgCl₂‐supported Ziegler catalyst

Cited by 21 publications

References 8 publications

Characterization and properties of polypropylene-block-poly(ethylene-co-propylene) synthesized by short-period polymerization

Characterization and properties of polypropylene-block-poly(ethylene-co-propylene) synthesized by short-period polymerization

Lifetime of growing polymer chain in stopped-flow propene polymerization using pre-treated Ziegler catalysts

Structure and Mechanical Behavior of the Mesomorphic Form in a Propylene-b-Poly(ethylene-co-propylene) Copolymer and Its Comparison with Other Thermal Treatments

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