Propylene polymerisations with novel heterogeneous combination metallocene catalyst systems

Tynys, Antti; Saarinen, Timo; Bartke, Michael; Löfgren, Barbro

doi:10.1016/j.polymer.2007.02.020

Cited by 19 publications

(16 citation statements)

References 28 publications

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“…[7,8] The observed viscosity reduction in conventional iPP is much more expressed in metallocene polypropylene due to its narrower MWD, needing sometimes mixing of two types of mPP to broaden the MWD. [2,5] The added nanofiller plays a similar role for enhancing viscosity reduction and here the minimum is observed at about 2-4 wt%, as seen in Figure 3.…”

Section: Resultssupporting

confidence: 55%

“…[1,2] Metallocene-based poly(propylene) (mPP) has many unique properties that are unattainable with the conventional catalyst systems as narrower molecular weight distribution (MWD), lower melt elasticity, lower melting and crystallization temperature and lower heat of fusion (hence less energy needed to change the polymer from the solid to the molten state). [3][4][5] The rheological properties of metallocene derived iPP in comparison with Ziegler-Natta derived iPP were investigated by Fujiyama and Inata. [6] These authors compared their samples with similar MFI and found that die swell, the entrance pressure loss, end correction coefficient and the critical shear rate at which a melt fracture begins to occur are lower.…”

Section: Introductionmentioning

confidence: 99%

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Conductive Composites Based on Metallocene Isotactic Poly(propylene): Preparation and Properties

Djoumaliisky

Benavente

Kotzev

et al. 2012

Macromolecular Symposia

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Summary:The research deals with the preparation and the further comprehensive characterization of metallocene polypropylene-based composite materials by incorporation of carbon black nanoparticles. Composites containing up to 10 wt% of carbon black were prepared by direct melt mixing in a single screw extruder Brabender Extrusiograph type 30/25D with attached static mixer at melt temperature of 200 8C and a screw speed of 30 rpm, according to a two-step process. Some composites were treated with 3 wt% maleic anhydride grafted polypropylene (MAH-PP). The rheological behaviour of the miPP nanocomposites was determined by cone/plate rheological measurements at 180 8C. The composites were characterized by SEM for morphological details and uniaxial stress-strain measurements for determining the mechanical parameters. Electric conductivity of injection molded plates from these composites was investigated. The different miPPs studied are ranked in an ascending order according to their increasing molecular weight concerning the magnitude of their rheological parameters. The maleic anhydride compatibilizer leads to lower viscosity values even at high shear gradients and to better homogenization of the nanofiller in the polymer matrix. The processing conditions, carbon black concentration and viscosity of the virgin polymer have an impact on the final conductivity of the miPP/carbon black composites.

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Section: Resultssupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Conductive Composites Based on Metallocene Isotactic Poly(propylene): Preparation and Properties

Djoumaliisky

Benavente

Kotzev

et al. 2012

Macromolecular Symposia

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show abstract

“…[13,14] Therefore, an economical and attractive route is to use two or more metallocene precursors simultaneously yielding a polypropylene mixture consisting of the polymer fractions produced by the different metallocenes individually. [15][16][17] In this sense, it is important to decide which catalytic sites with different kinetic responses, such as different propagation and termination rate constants are needed in order to produce a blend of polymeric chains with different predominant molecular weights.…”

Section: Introductionmentioning

confidence: 99%

Bimodal Poly(propylene) through Binary Metallocene Catalytic Systems as an Alternative to Melt Blending

Moya¹,

Grieken²,

Carrero

et al. 2012

Macromolecular Symposia

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Summary: Propylene was polymerized by three homogenous metallocene catalytic systems: rac-Me 2 Si (Ind) 2 ZrCl 2 (CAT-1), rac-Et(Ind) 2 ZrCl 2 (CAT-2) and rac-Me 2 Si(2-Mebenzoind) 2 ZrCl 22 ZrCl 2 (CAT-3) at 50 8C. In function of the molecular-average weight results of poly(propylene)s obtained, rac-Et(Ind) 2 ZrCl 2 (CAT-2) and rac-Me 2 Si(2-Mebenzoind) 2 ZrCl 2 (CAT-3) were combined in different proportions (wt %/wt %) of (CAT-2/CAT-3) for obtaining a new poly(propylene) with a bimodal molecular weight distribution consisting in clearly separated low and high molecular weight polymer fractions with a difference between them of an order of magnitude. The polymers obtained were compared with those coming from melt mixing of two poly(propylene)s with different molecular weights in an extruder. Both methods allow obtaining bimodal poly(propylene)s, but polymer melt blending shows partial miscibility effects and less crystallinity while binary catalytic systems have several advantages such as lower costs and easier to process that can be controlled to tailor properties together with intimate mixing of high and low molecular weight components.

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“…An alternative are single-site catalysts (SSC), especially metallocenes which have been tested in PP production since the mid-1990s [9,10]. While early SSC generations were too limited in terms of catalyst lifetime and molecular weight, more recent developments as studied for example by Tynys and coworkers [11,12] have also enabled the production of SSC-based EP-HECOs. In the present paper an asymmetric zirconocene similar to the ones in [12] was used to polymerize such copolymers in a wide composition range to study structure-property relations.…”

mentioning

confidence: 99%

“…While early SSC generations were too limited in terms of catalyst lifetime and molecular weight, more recent developments as studied for example by Tynys and coworkers [11,12] have also enabled the production of SSC-based EP-HECOs. In the present paper an asymmetric zirconocene similar to the ones in [12] was used to polymerize such copolymers in a wide composition range to study structure-property relations. It should be mentioned that also hybrid catalyst systems with a combination of ZNC and SSC have been tested by a number of authors [13,14], with the main advantage seen in the possibility to use higher α-olefins like 1-octene [14] for polymer design.…”

mentioning

confidence: 99%

Structure-property relations of heterophasic ethylene-propylene copolymers based on a single-site catalyst

Aarnio-Winterhof¹,

Doshev²,

Seppälä³

et al. 2017

Express Polym. Lett.

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Propylene polymerisations with novel heterogeneous combination metallocene catalyst systems

Cited by 19 publications

References 28 publications

Conductive Composites Based on Metallocene Isotactic Poly(propylene): Preparation and Properties

Conductive Composites Based on Metallocene Isotactic Poly(propylene): Preparation and Properties

Bimodal Poly(propylene) through Binary Metallocene Catalytic Systems as an Alternative to Melt Blending

Structure-property relations of heterophasic ethylene-propylene copolymers based on a single-site catalyst

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