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Auteur : Grafiati
Publié le 10 mars 2023

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1

An, Meiru, Binran Cui et Xintong Duan. « Preparation and applications of linear low-density polyethylene ». Journal of Physics : Conference Series 2229, no 1 (1 mars 2022) : 012009. http://dx.doi.org/10.1088/1742-6596/2229/1/012009.

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Abstract Linear low-density polyethylene (LLDPE) is widely used in many fields like packaging and film due to its chemical resistance and high tensile strength. This review mainly introduces the preparations and applications of LLDPEs produced by Ziegler-Natta catalyst, metallocene-based catalyst, and late transition metal catalyst, respectively. The improved mechanical and conductivity properties of LLDPE by Ziegler-Natta catalysts, higher activity of the metallocene-based catalysts and high performance of LLDPE directly produced by late transition metal were highlighted. The enhancement of the resistance, flexibility, transparency properties, and yield is achieved using those catalysts and mild conditions. This also leads to more applications in electrical, medical, and surgical areas and can reach an industrial scale.
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2

Auriemma, Finizia, et Claudio De Rosa. « Theoretical investigation of (MgCl2)xpolynuclear species formed during preparation of MgCl2-supported Ziegler–Natta catalysts from solid solvates ». Journal of Applied Crystallography 41, no 1 (16 janvier 2008) : 68–82. http://dx.doi.org/10.1107/s0021889807054453.

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A novel approach for the study of the nature of the active species in Ziegler–Natta catalysis is described. This approach is based on the study of reliable structural models for disordered (MgCl2)xpolynuclear species which develop during the preparation of MgCl2-supported catalysts starting from MgCl2–Lewis-base adducts, and the calculation of X-ray diffraction patterns of these models. A method for the calculation of the X-ray powder diffraction patterns of the model structures is devised. This diffraction modelling method may be useful for the correct interpretation of the nature of some diffraction features in the X-ray diffraction patterns recorded during the structural evolution of MgCl2–Lewis-base adducts, which occurs in the preparation of the catalyst systems used for Ziegler–Natta polymerization of olefins.
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3

Zhou, Wei, Lei Zhong et Wei Dong Li. « Progress in Development of Catalyst Systems for Coordinated Polymerization of Olefins ». Advanced Materials Research 900 (février 2014) : 11–14. http://dx.doi.org/10.4028/www.scientific.net/amr.900.11.

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The research progresses about polyolefin catalyst systems in recent years are summarized. Focusing on the type and properties of the catalytic polymerization of the olefin polymerization catalyst, including typical Ziegler-Natta catalysts, metallocene catalysts and post-transition metal catalyst system. Then the new post-transition metal catalyst is introduced.
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4

Liu, Zhaoxiang, et Haochen Zhang. « Ultra-high molecular weight polyethylene : preparation and applications ». Journal of Physics : Conference Series 2229, no 1 (1 mars 2022) : 012006. http://dx.doi.org/10.1088/1742-6596/2229/1/012006.

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Abstract Ultra-high molecular weight polyethylene is a kind of popular engineering material because of its unique properties stemming from high molecular weights. Nowadays, the preparations and applications of this type of material are widely researched. This review mainly focuses on the preparation of ultra-high molecular weight polyethylene using three types of typical catalysts (heterogeneous Ziegler-Natta catalysts, Fujita’s catalysts and α-Diimine Nickel (II) catalysts) and applications in two significant areas (bulletproof membranes and lithium-ion batteries). Ziegler-Natta catalysts and Fujita’s catalysts favor the synthesis of linear ultra-high molecular weight polyethylene, but α-Diimine Nickel (II) catalysis favors β-hydride elimination which leads to branched products. Changes in steric, composition, activators, temperature and pressure will affect the tendency towards different mechanisms and influence structures and properties of final products.
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5

Govindaswamy, Padavattan, Emiko Wada, Hiroyuki Kono, Toshiya Uozumi et Hideo Funabashi. « Propylene Polymerization Performance with Ziegler-Natta Catalysts Combined with U-Donor and T01 Donor as External Donor ». Catalysts 12, no 8 (5 août 2022) : 864. http://dx.doi.org/10.3390/catal12080864.

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In propylene (C3) polymerization with Ziegler-Natta catalyst, not only internal donor but also external donor is very important to make isotactic polypropylene (PP) with higher yield. Most propylene-based polymers have been commercially produced with Ziegler-Natta catalysts combined with dialkyl-dialkoxy silane compounds (R2Si(OR)2) such as C-donor, P-donor, and D-donor as external donors. In this paper, we will introduce the propylene polymerization performance with aminosilane compounds, i.e., diethylamino triethoxy silane (U-donor) and bis(ethylamino) di-cyclopentyl silane (T01 donor), as external donor in Ziegler–Natta catalyst. The polymerization screening experiments were conducted using some triethoxyalkylsilanes compounds (1–7) and performances were compared with U-donor. The polymerization results of the binary donor system show improvement in stereoregularity. These aminosilane compounds exhibit high hydrogen response in propylene polymerization and high copolymerization performance of propylene (C3) and ethylene (C2) in ICP production compared with dialkyl-dialkoxy silane compounds. While using methanol as an additive along with external electron donor, as a serendipitous, the copolymerization activity, block ratio, EPR (ethylene-propylene rubber) content improve significantly for U-donor as compared with T01 donor and C-donor.
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6

Wang, Jing, Xiao Yan Liu, Jun Ji Jia, Xu Chen et Bo Chao Zhu. « Study of Ziegler-Natta /Metallocene Hybrid Catalyst on Pilot Device ». Advanced Materials Research 396-398 (novembre 2011) : 8–12. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.8.

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In this work, Ziegler-Natta/Metallocene hybrid catalyst (Z-M) was prepared magnifying. The activity and copolymerization behavior of the catalyst were evaluated through 10L model device. Model experiment results confirmed that the catalyst was suitable for Spheripol-II PP pilot device. Subsequently, pilot experiment was carried out on 75 kgPP/h Spheripol-II PP pilot device. SP179 which was prepared by traditional Ziegler-Natta catalyst was used as a reference object. Pilot experiment results showed that: Z-M hybrid catalyst demonstrated good activity and copolymerization properties. The resultant polypropylene in-reactor alloys have better impact strength and flowability than SP179. These alloys showed good stiffness-toughness balance. The impact strength and the flexural modulus of the best alloy was 50 kJ/m2 at 23 °C and 848 MPa, respectively. The other performances were similar to that of SP179. But Z-M hybrid catalyst required lower feed ratio of ethylene than the traditional Ziegler-Natta catalyst for SP179.
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7

Oleshko, V., P. Crozier, R. Cantrell et A. Westwood. « In Situ and Ex Situ Microscopic Study of Propylene Polymerization With Heterogeneous Mgcl2-Supported Ziegler-Natta Catalysts ». Microscopy and Microanalysis 6, S2 (août 2000) : 33–34. http://dx.doi.org/10.1017/s1431927600032657.

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The large-scale commercial production of polyolefins by catalytic Ziegler-Natta polymerization have stimulated the development of the third, fourth and fifth generation heterogeneous catalysts comprising high surface area defective MgCl2 with TiCl4, electron donors, and AlR3-co-catalysts. In spite of intensive research over the years, the present level of understanding of the catalysts is still incomplete because of their complex composition leading to a multitude of local active site environments. The aim of this work is to provide a new insight into the process via in situ video microscopy of gas phase propylene polymerization over MgCl2-supported Ziegler-Natta catalysts combined with ex situ characterization by light and electron microscopy techniques (SEM, TEM, HRTEM, STEM, PEELS and windowless EDX). Procedures for catalyst synthesis are described elsewhere. The catalysts were stored in a dry box under a He atmosphere (<lppm H2O/O2). Samples were transferred to specimen holders in the dry box and then transferred into the microscopes under high purge N2 conditions to prevent poisoning of the catalysts by air and moisture.
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8

Varshouee, Gholam Hossain, Amir Heydarinasab, Ali Vaziri et Seyed Mehdi Ghafelebashi Zarand. « A Mathematical Model for Investigating the Effect of Reaction Temperature and Hydrogen Amount on the Catalyst Yield during Propylene Polymerization ». Kemija u industriji 68, no 7-8 (2019) : 269–80. http://dx.doi.org/10.15255/kui.2018.048.

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In this study, the effect of reaction temperature and hydrogen amount, as the most effective process variables on the Ziegler-Natta catalysts yield during propylene polymerization, was investigated with the aid of a validated mathematical model. The approach applied in this modelling was the &lt;i&gt;polymer moment balance technique&lt;/i&gt; (&lt;i&gt;population balance approach&lt;/i&gt;) derived from the statistics expected value. The model was coded in MATLAB&lt;sup&gt;®&lt;/sup&gt; &amp; Simulink&lt;sup&gt;®&lt;/sup&gt;, and then validated by experimental data coming from a laboratory-scale reactor. The main target of this study was to gain considerable insight into Ziegler-Natta catalyst performance against variables change. The model might be applicable for catalyst makers to evaluate and improve their catalysts, and could also be useful for process chemical engineers to easily operate the plant, replace new catalyst, optimise process conditions, generate new formulation for a new grade, and use maximum catalytic potential. Accordingly, the model could be applied in basic and applied research in this field.
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9

Zhang, He-xin, Byeong-Gwang Shin, Dong-Eun Lee et Keun-Byoung Yoon. « Preparation of PP/2D-Nanosheet Composites Using MoS2/MgCl2- and BN/MgCl2-Bisupported Ziegler–Natta Catalysts ». Catalysts 10, no 6 (27 mai 2020) : 596. http://dx.doi.org/10.3390/catal10060596.

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Polypropylene/molybdenum disulfied (PP/MoS2) and Polypropylene/hexagonal boron nitride (PP/hBN) nanocomposites with varying concentration (0–6 wt %) were fabricated via in situ polymerization using two-dimensional (2D)-nanosheet/MgCl2-supported Ti-based Ziegler–Natta catalysts, which was prepared through a novel coagglomeration method. For catalyst preparation and interfacial interaction, MoS2 and hBN were modified with octadecylamine (ODA) and octyltriethoxysilane (OTES), respectively. Compared with those of pristine PP, thermal stability of composites was 70 °C higher and also tensile strength and Young’s modulus of the composites were up to 35% and 60% higher (even at small filler contents), respectively. The alkyl-modified 2D nanofillers were characterized by strong interfacial interactions between the nanofiller and the polymer matrix. The coagglomeration method employed in this work allows easy introduction and content manipulation of various 2D-nanosheets for the preparation of 2D-nanosheet/MgCl2-supported Ti-based Ziegler–Natta catalysts.
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10

Jiang, Tao, et Xiang Lu Gao. « Preparation of Polyethylene with Vanadium/Titanium Bi-Metal Ziegler-Natta Catalysts ». Applied Mechanics and Materials 665 (octobre 2014) : 335–38. http://dx.doi.org/10.4028/www.scientific.net/amm.665.335.

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The catalyst with magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts has been prepared. The effects of V/Ti molar ratio and dosage of α-olefin on catalytic activity of ethylene polymerization were investigated. Gel permeation chromatography (GPC),13C-NMR spectra and differential scanning calorimetry (DSC) analysis were performed to characterize the polymers. The results indicated that the bimetallic catalyst system produced PE with broad and bimodal MWD.
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11

Yan, Yibin, Dengfei Wang, Shuyan He, Hegang Ren et Yongjun Xu. « Study on the synthesis of hexene-1 catalyzed by Ziegler-Natta catalyst and polyhexene-1 applications ». e-Polymers 19, no 1 (4 octobre 2019) : 511–18. http://dx.doi.org/10.1515/epoly-2019-0054.

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AbstractThis paper presents the synthesis of two aminosilane-based external donors for the Ziegler-Natta catalysis: di(piperidyl) dimethoxysilane (DPPDMS) and dipyrrolyldimethoxysilane (DPRDMS). We compared the electron donation by these two compounds in the MgCl2- supported Ziegler-Natta catalysis of the polymerization of hexene-1 into a polyhexene-1 (PHe) elastomer with that of the common donor cyclohexylmethyldimethoxysilane (CHMMS). The catalytic activity of the system and isotacticity of the polymer (PHe) product improved significantly because of the considerable steric hindrance and strong electronic effects of these aminosilane-based external donors. The effects of different external donors on the catalytic efficiency, polymer isotacticity, molecular weight and molecular weight distribution of the PHe products were investigated. Under the best reaction conditions, the catalyst activity, polymer molecular weight, and glass-transition temperature were determined as 899 g/g Cat·h-1, MW = 252,300 g/mol, and -41.39°C, respectively. The PHe was characterized by FTIR and NMR. This report also describes blending of PHe and low density polyethylene that leads to a significant increase in the impact strength and elongation at breaks.
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12

Wang, Xiong, Dong Wu, Xuemei Mu, Wenqian Kang, Guangquan Li, Anping Huang et Yuan Xie. « Porous Organic Polymers-Supported Zeigler-Natta Catalysts for Preparing Highly Isotactic Polypropylene with Broad Molecular Weight Distribution ». Polymers 15, no 3 (21 janvier 2023) : 555. http://dx.doi.org/10.3390/polym15030555.

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Porous organic polymers (POPs) have attracted much attention in numerous areas, including catalysis, adsorption and separation. Herein, POP supported Ziegler–Natta catalysts were designed for preparation of isotactic polypropylene (iPP). The POPs-based Ziegler–Natta catalysts exhibited the characteristic of broad molecular weight distribution (MWD > 11) with or without adding an extra internal electron donor. The added internal electron donor 3-methyl-5-tert-butyl-1,2-phenylene dibenzoate (ID-2) used in cat-2 showed good propylene polymerization activity of 15.3 × 106 g·PP/mol·Ti·h, high stereoregularity with 98.2% of isotacticity index and broad molecular weight distribution (MWD) of 12.3. Compared to the MgCl2-supported Ziegler–Natta catalysts (cat-4) with the same ID-2, cat-2 showed higher chain stereoregularity for propylene polymerization. As seen in the TREF results, the elution peak of PP-2 (124.0 °C, 91.7%) is 1.5 °C higher than the isotactic fraction from PP-4 (122.5 °C, 87.2%), and even 1.2 °C higher than PP-5 prepared from ID-3 with the characteristics of high stereoregularity. Moreover, the pentad methyl sequence mmmm of PP-2 (93.0%) from cat-2 is 0.5% higher than that of PP-4 from cat-4. XPS analysis revealed that the minute difference in binding energy of Ti, Mg, C and O atoms exist between the inorganic MgCl2 and the organic polymer based Z–N catalysts. The plausible interaction mechanism of active sites of Mg and Ti with the functional groups in the POP support and the added ID was proposed, which could be explained by their high stereoregularity and the broad molecular weight distribution of the POP-based Z–N catalysts.
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13

Walton, Kim L., Morgan M. Hughes et Deepak R. Parikh. « A New Class of Ethylene—Propylene—Diene Terpolymers Produced from Constrained Geometry Metallocene Catalysts ». Rubber Chemistry and Technology 74, no 4 (1 septembre 2001) : 688–700. http://dx.doi.org/10.5254/1.3544967.

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Abstract Until recently, ethylene/propylene/diene (EPDM) terpolymers have been manufactured exclusively using vanadium based Ziegler—Natta catalyst systems. The vanadium based catalysts are known to have both product and process limitations. These limitations are due to a complex combination of factors including monomer reactivity, catalyst activity, reactor temperatures and pressures. Single-site metallocene constrained geometry catalyst (CGC) technology enables the manufacture of EPDM terpolymers at higher reactor temperature and catalyst efficiency than standard Ziegler—Natta catalyst systems. The unique combination of monomer, catalyst and process technology enables the manufacture of highly crystalline EPDMs having ethylene contents over 90 wt %. This study investigated these new highly crystalline EPDM terpolymers and their differentiation from commercially available EPDMs. The results indicated that these new EPDMs had very high green strength and barrier properties, yet could be cured by conventional vulcanization techniques. The cure response of these EPDMs to either peroxide or sulfur increased with increasing ethylene content. Sulfur cured vulcanizates had much higher tensile strength than peroxide cured vulcanizates. These new EPDMs demonstrated utility as additives to enhance the abrasion, hot tear, and tensile properties of natural rubber compounds. Sponge compounds, having the unique combination of polyethylene physical properties and the utility of sulfur vulcanization were developed from these new polymers.
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14

Semsarzadeh, Mohammad Ali, et Alireza Aghili. « Ethylene Extrusion Polymerization by Heterogeneous bi-Supported Ziegler-Natta Catalysts ». Chemistry & ; Chemical Technology 3, no 1 (15 mars 2009) : 67–72. http://dx.doi.org/10.23939/chcht03.01.067.

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The MCM-41 (Mobil Composition of Matter) and SBA-16 (Santa Barbara Amorphous) supported TiCl4 and TiCl4/MgCl2 catalysts with different molar ratios of Mg/Ti were synthesized and used for ethylene polymerization under atmospheric pressure. The nanochannels of these supports serve as a nanoscale polymerization reactor and the polyethylene nanofibers were extruded during the reaction. The effect of MgCl2 on catalytic activity and morphology of resulting polyethylene has been investigated too. MgCl2 has enhanced the catalytic activities and made the SBA-16/MgCl2/TiCl4 catalytic system has fibrous morphology.
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15

Schwarz, Julia Felicitas, Thorsten Holtrichter-Rößmann, Claus Günter Liedtke, Diddo Diddens et Christian Paulik. « Modified Magnesium Alkyls for Ziegler–Natta Catalysts ». Catalysts 12, no 9 (30 août 2022) : 973. http://dx.doi.org/10.3390/catal12090973.

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Magnesium alkyls such as butyl octyl magnesium and butyl ethyl magnesium are used as precursors for highly active and water-free magnesium chloride support materials for Ziegler–Natta catalysts. These alkyls show a high viscosity in hydrocarbon solvents which negatively affect their industrial application. Density functional theory (DFT) calculations supported the hypothesis that magnesium alkyls can form oligomeric chain structures responsible for the high viscosity. Heterocumulenes such as isocyanates, isothiocyanates and carbodiimides were studied as additives reducing the viscosity, supported by DFT calculations. The modified alkyls have further been tested in catalyst synthesis and in the polymerization of ethylene. The polymerization results showed high activities and similar polymer properties compared with a catalyst prepared without modified magnesium alkyl.
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Li, Chuang, Zefeng Cui, Min Yang, Haifeng Shi et Binyuan Liu. « Preparation and crystalline transformation of functionalized poly(1-butene) containing PFPU and mPEG side chain ». RSC Advances 11, no 59 (2021) : 37317–24. http://dx.doi.org/10.1039/d1ra07698a.

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17

Kumawat, Jugal, et Virendra Kumar Gupta. « Fundamental aspects of heterogeneous Ziegler–Natta olefin polymerization catalysis : an experimental and computational overview ». Polymer Chemistry 11, no 38 (2020) : 6107–28. http://dx.doi.org/10.1039/d0py00753f.

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18

Podvorica, Leonora, Enrico Salvadori, Fabrizio Piemontesi, Gianni Vitale, Giampiero Morini et Mario Chiesa. « Isolated Ti(III) Species on the Surface of a Pre-active Ziegler Natta Catalyst ». Applied Magnetic Resonance 51, no 11 (22 septembre 2020) : 1515–28. http://dx.doi.org/10.1007/s00723-020-01266-2.

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AbstractThe nature of Ti(III) species, introduced in working models of industrial Ziegler Natta catalyst precursors, consisting of MgCl2/TiCl4 binary systems, eventually containing different Lewis basis, are studied by a combination of X- and Q-band CW and pulse EPR spectroscopy. In Ziegler Natta catalysts, Ti(III) play the double role of active catalytic species and unconventional spin probes. On the binary system, two dominant Ti(III) species, characterized by distinctively different EPR spectra, are observed. 35,37Cl Q-Band HYSCORE spectra allow estimating the hyperfine and nuclear quadrupole interactions of directly coordinated Cl, characterized by a hyperfine dipolar contribution of the order of 5 MHz and nuclear quadrupole interactions of the order of e2qQ/h = 9 MHz. Interestingly, the two dominant EPR active species are selectively suppressed by the presence of different Lewis bases, indicating the possibility to address the long standing issue of the influence of Lewis bases in driving specific morphological configurations and influencing the catalytic properties of Ti(III) active sites.
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19

Zhang, Min, Jinling Liu, Yiguang Wang, Linan An, Michael D. Guiver et Nanwen Li. « Highly stable anion exchange membranes based on quaternized polypropylene ». Journal of Materials Chemistry A 3, no 23 (2015) : 12284–96. http://dx.doi.org/10.1039/c5ta01420d.

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20

Wu, Chaofan, Tengjie Ge, Zeyu Jiang, Yanfeng Jiang, Qian Zhang et Jian Li. « Immobilizing metallocene by solid polymethylaluminoxane “sMAO” for slurry-phase ethylene-1-hexene copolymerization ». MATEC Web of Conferences 358 (2022) : 01017. http://dx.doi.org/10.1051/matecconf/202235801017.

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In the field of olefin catalytic polymerization, metallocene catalysts show higher activity than traditional Ziegler-Natta catalysts. In this study, benzoic acid catalyzed the controlled hydrolysis of trimethylaluminum (TMA) to methylaluminoxane (MAO). After pyrolysis, an insoluble form of solid polymethylaluminoxane (sMAO) was synthesized. The influence of synthesis conditions on the particle size and morphy was systematically explored. The synthetic sMAO is used as a carrier to support the metallocene catalyst, and the catalyst is applied to the ethylene/1-hexene copolymerization. The experimental results show that the activity can be as high as 12149.8 gPEꞏ(gcat)-1 when the slurry reaction is catalyzed in a 5L kettle.
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Zhang, Hao, He-Xin Zhang et Keun-Byoung Yoon. « Synthesis of polyethylene/exfoliated MoS2 nanocomposites by in situ exfoliation polymerization using Ziegler–Natta catalyst intercalated MoS2 ». RSC Advances 7, no 82 (2017) : 52048–52. http://dx.doi.org/10.1039/c7ra10853b.

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Udayakumar, Sanjith, Najwa Ibrahim, Chan Yong Chien, Shaikh Abdul Rahman Shaik Abdul Wahab, Ahmad Fauzi Mohd Noor et Sivakumar Ramakrishnan. « Synthesis of Ziegler-Natta Catalyst using Malaysian Ilmenite Derived TiCl4 via Recrystallization Method : A Statistical Approach ». Bulletin of Chemical Reaction Engineering & ; Catalysis 15, no 3 (13 août 2020) : 687–97. http://dx.doi.org/10.9767/bcrec.15.3.8195.687-697.

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In the current study, Ziegler-Natta (Z-N) catalyst was synthesized via recrystallization method using MgCl2 as a support, AlCl3 as an activator and TiCl4 as a transition metal source. The TiCl4 used in the study was derived from Malaysian ilmenite through a sequential pyrometallurgical and hydrometallurgical process of ilmenite concentrate conversion to TiCl4. The recrystallization method of synthesis of the heterogeneous Z-N catalyst was studied by varying the synthesis parameters, such as the combined amount of MgCl2 and AlCl3, temperature, and amount of TiCl4, using statistical design of experiments. The investigation aimed at determining the best conditions for synthesizing the heterogeneous Z-N catalyst. The synthesis conditions posed a significant influence on the Ti content present in the catalyst product. The morphological and elemental analysis of SEM-EDX showed good spherical nature of the prepared catalysts. The XRD phase analysis detected the peaks of MgCl2, MgCl2-Ethanol, MgCl2/TiClx, and TiO2. The IR spectra confirmed the presence of the Mg-Cl bond at 1635 cm−1 and Ti-Cl bonds at 602 cm-1 and 498 cm-1. The produced catalyst contained a small amount of TiO2, which could be due to the seepage of moisture during the analysis or storage of the sample. The most favourable combination of the studied parameters was determined based on the Ti content in the catalyst product. Therefore, the best conditions for synthesizing the heterogeneous Z-N catalyst with high Ti content (181.1 mg/L) was at a combined amount of 2 g of MgCl2 for 6 g of AlCl3, crystallization temperature of 80 °C, and 2 mL dosage of TiCl4. Copyright © 2020 BCREC Group. All rights reserved
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Blaakmeer, E. S. (Merijn), Ernst R. H. van Eck et Arno P. M. Kentgens. « The coordinative state of aluminium alkyls in Ziegler–Natta catalysts ». Physical Chemistry Chemical Physics 20, no 12 (2018) : 7974–88. http://dx.doi.org/10.1039/c8cp00603b.

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24

Busico, Vincenzo. « Ziegler-Natta catalysis : Forever young ». MRS Bulletin 38, no 3 (mars 2013) : 224–28. http://dx.doi.org/10.1557/mrs.2013.50.

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25

KOLTHAMMER, B. W. S. « ChemInform Abstract : Ziegler-Natta Catalysis ». ChemInform 28, no 2 (4 août 2010) : no. http://dx.doi.org/10.1002/chin.199702245.

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Abboud, Mohammed, Peter Denifl et Karl-Heinz Reichert. « Advantages of an Emulsion-Produced Ziegler-Natta Catalyst Over a Conventional Ziegler-Natta Catalyst ». Macromolecular Materials and Engineering 290, no 12 (15 décembre 2005) : 1220–26. http://dx.doi.org/10.1002/mame.200500209.

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Zhang, He-Xin, Jae-Hyeong Park, Eun-Bin Ko, Young-Kwon Moon, Dong-ho Lee, Yan-Ming Hu, Xue-Quan Zhang et Keun-Byoung Yoon. « Comparison of the properties of graphene- and graphene oxide-based polyethylene nanocomposites prepared by an in situ polymerization method ». RSC Advances 6, no 77 (2016) : 73013–19. http://dx.doi.org/10.1039/c6ra11858e.

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A facile coagglomeration method for preparing a G(O)/MgCl2-supported Ziegler–Natta catalyst was reported. The effect of G and GO on the physical properties of polyethylene were comparably investigated.
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Bronskaya, Veronika, Galiya Manuyko, Guzel Aminova, Olga Kharitonova, Denis Balzamov et Alsu Lubnina. « Temperature Dependence of the Kinetic Parameters of the Titanium–Magnesium Catalyzed Propylene Polymerization ». Polymers 14, no 23 (28 novembre 2022) : 5183. http://dx.doi.org/10.3390/polym14235183.

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This paper provides a study of the liquid-phase polypropylene polymerization on a heterogeneous titanium–magnesium Ziegler–Natta-type catalyst. A kinetic model was developed that included the activation of potential active centers, chain growth, transferring the chains to hydrogen and monomer, and the deactivation of active centers. The model was created to predict the polymerization rate, polymer yield, and average molecular weights of polymer chains where the polymerization temperature changes from 40 to 90 °C. In developing polycentric kinetic models, there is a difficulty associated with evaluating the kinetic constants of the rates of elementary reactions/stages in polymerization. Each heterogeneous titanium–magnesium catalyst (TMC), including a co-catalyst, as well as an internal and an external electron donor, has its own set of kinetic parameters. Therefore, its kinetic parameters must be defined for each new catalyst. The presented algorithm for identifying the kinetic constants of rates starts with a kinetic model that considers one type of active centers. At the second stage, a deconvolutional analysis is used for the molecular weight distribution (MWD) of the gel permeation chromatography (GPC) data of the polypropylene samples and the most probable distribution of Flory chain lengths is found for each type of active centers. At the third stage, the single-center model is transformed into a polycentric kinetic model. For the catalyst system, five types of active centers were identified, together with a mass fraction and a number-average molecular weight for each active center type of the catalyst, which is consistent with the published results for similar Ti-based Ziegler–Natta catalysts.
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Mileva, Daniela, Jingbo Wang, René Androsch, Katalee Jariyavidyanont, Markus Gahleitner et Klaus Bernreitner. « Crystallization of Random Metallocene-Catalyzed Propylene-Based Copolymers with Ethylene and 1-Hexene on Rapid Cooling ». Polymers 13, no 13 (25 juin 2021) : 2091. http://dx.doi.org/10.3390/polym13132091.

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Propylene-based random copolymers with either ethylene or 1-hexene as comonomer, produced using a metallocene catalyst, were studied regarding their crystallization behaviors, with a focus on rapid cooling. To get an impression of processing effects, fast scanning chip calorimetry (FSC) was used in addition to the characterization of the mechanical performance. When comparing the comonomer type and the relation to commercial grades based on Ziegler–Natta-type catalysts, both an interaction with the catalyst-related regio-defects and a significant difference between ethylene and 1-hexene was observed. A soluble-type nucleating agent was found to modify the behavior, but to an increasingly lesser degree at high cooling rates.
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Ren, Yixin, Justin T. Miller, Stefanie T. Polderman, Trinh D. Vo, Adele C. M. Wallace, John Michael O. Cue, Sarah T. Tran, Michael C. Biewer et Mihaela C. Stefan. « Halide-free neodymium phosphate based catalyst for highly cis-1,4 selective polymerization of dienes ». RSC Advances 9, no 6 (2019) : 3345–50. http://dx.doi.org/10.1039/c8ra10050k.

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Comparán-Padilla, Víctor E., Maricela García-Zamora, Ramiro Infante-Martínez, José A. Díaz, Luis Villarreal-Cárdenas, María T. Rodríguez-Hernández et Odilia Pérez-Camacho. « Coordination copolymerization monitoring of ethylene and alfa-olefins by in-line Raman spectroscopy ». RSC Advances 12, no 44 (2022) : 28712–19. http://dx.doi.org/10.1039/d2ra05213j.

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Copolymerizations of ethylene and alfa-olefins, using Ziegler–Natta or metallocene catalysts, testing two methods of co-monomer addition, through batch or dossing mode during the reactions, are reported in this work.
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Córdova, Teresa, Francisco Javier Enríquez-Medrano, Eduardo Martínez Cartagena, Arnulfo Banda Villanueva, Luis Valencia, Edgar Nazareo Cabrera Álvarez, Ricardo López González et Ramón Díaz-de-León. « Coordinative Chain Transfer Polymerization of Sustainable Terpene Monomers Using a Neodymium-Based Catalyst System ». Polymers 14, no 14 (17 juillet 2022) : 2907. http://dx.doi.org/10.3390/polym14142907.

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The present investigation involves the coordinative chain transfer polymerization (CCTP) of biobased terpenes in order to obtain sustainable polymers from myrcene (My) and farnesene (Fa), using the ternary Ziegler–Natta catalyst system comprising [NdV3]/[Al(i-Bu)2H]/[Me2SiCl2] and Al(i-Bu)2H, which acts as cocatalyst and chain transfer agent (CTA). The polymers were produced with a yield above 85% according to the monomeric consumption at the end of the reaction, and the kinetic examination revealed that the catalyst system proceeded with a reversible chain transfer mechanism in the presence of 15–30 equiv. of CTA. The resulting polyterpenes showed narrow molecular weight distributions (Mw/Mn = 1.4–2.5) and a high percent of 1,4-cis microstructure in the presence of 1 equiv. of Me2SiCl2, having control of the molecular weight distribution in Ziegler–Natta catalytic systems that maintain a high generation of 1,4-cis microstructure.
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Murray, Michael C., et Michael C. Baird. « Polymerization of 1-hexene catalyzed by Cp*TiMe3-B(C6F5)3 ; a mechanistic and structural study ». Canadian Journal of Chemistry 79, no 5-6 (1 mai 2001) : 1012–18. http://dx.doi.org/10.1139/v00-183.

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Solutions of the Ziegler–Natta system Cp*TiMe3 – B(C6F5)3 in toluene catalyze the polymerization of 1-hexene to mixtures of atactic poly-1-hexenes and complex oligomeric materials, which were characterized by 1H and 13C{1H} NMR spectroscopy and gel permeation chromatography (GPC). The polymer molecular weights and the relative proportions of polymers and oligomers vary with temperature, monomer:catalyst ratios, and degree of dilution and may generally be rationalized in terms of a conventional Ziegler–Natta mechanism. The 13C{1H} NMR spectra of the polymers exhibit resonances suggesting significant degrees of 2,1-insertions during propagation, while experiments utilizing Cp*Ti(13CH3)3 verify that initiation in toluene involves predominantly via 1,2-insertion of the first monomer unit but that 2,1-insertions occur up to 15–20% of the time in CH2Cl2. NMR experiments involving Cp*Ti(13CH3)3 demonstrate that both methyl groups in the presumed active species Cp*TiMe+2 are incorporated into polymerKey words: titanium, polymers, polymerization, Ziegler–Natta
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Ikeda, Tomohiro, Toru Wada, Yusuke Bando, Patchanee Chammingkwan et Toshiaki Taniike. « Bottom-Up Synthesis of Multi-Grained Ziegler–Natta Catalyst Based on MgO/MgCl2/TiCl4 Core–Shell Catalyst ». Catalysts 11, no 9 (10 septembre 2021) : 1092. http://dx.doi.org/10.3390/catal11091092.

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Morphology control plays a major role in the design of solid catalysts. Since the heterogeneous Ziegler–Natta catalyst (ZNC) is based on the in situ synthesis of MgCl2 support in a top-down manner, the individual control of the exterior and the interior structure of the catalyst macro-particles is challenging. In this study, we successfully prepared a ZNC with a multi-grain interior structure by the spray-drying of MgO nanoparticles, inspired by the fact that the MgO/MgCl2/TiCl4 core–shell catalyst can maintain the morphology of the raw MgO nanoparticles. This catalyst is the first example of the bottom-up preparation of MgCl2-supported ZNC. Here, we report its basic preparation method, characterization results, and performance in the homo-polymerization of ethylene and propylene, and copolymerization with 1-hexene.
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De Rosa, Claudio, Odda Ruiz de Ballesteros, Rocco Di Girolamo, Anna Malafronte, Finizia Auriemma, Giovanni Talarico et Miriam Scoti. « The blocky structure of Ziegler–Natta “random” copolymers : myths and experimental evidence ». Polymer Chemistry 11, no 1 (2020) : 34–38. http://dx.doi.org/10.1039/c9py01485c.

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When Ziegler–Natta catalysts synthesize “random” copolymers, they give multiblocks copolymers. Chains of butene–ethylene copolymers contain blocks with long and short butene sequences that crystallize in forms II and I of iPB, respectively.
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A. AL-Temimei, Faeq, et Hamid I. Abbood. « Electronic Structure, IR and UV-Vis Spectra of Some Suggested Ziegler-Natta Catalysts ». Journal of Kufa Physics 10, no 01 (10 juin 2018) : 87–94. http://dx.doi.org/10.31257/2018/jkp/100111.

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KIOKA, MAMORU. « Recent advances in ziegler natta catalyst. » NIPPON GOMU KYOKAISHI 62, no 10 (1989) : 641–49. http://dx.doi.org/10.2324/gomu.62.641.

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38

Baird, Michael C. « Catalysis by organotransition metal compounds : Synergism between the pure and the applied1 ». Canadian Journal of Chemistry 81, no 4 (1 avril 2003) : 330–37. http://dx.doi.org/10.1139/v03-065.

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The modern era of transition-metal-catalyzed polymerization of alkenes began with the Nobel Prize winning work of Ziegler and Natta in the 1950s, but the field has exploded since the mid-1980s and anticipated applications of organometallic catalysts are being spectacularly realized. Our research in metal-catalyzed alkene polymerization began about ten years ago with an investigation of the catalytic applications of half-sandwich complexes of the Group 4 metals, and this lecture will describe our efforts to find both better initiators to make known commercial polymers and new initiators to make novel polymeric materials. Good luck, bad luck, blind alleys, and serendipity have all played key roles in our research, resulting ultimately in a very satisfying convergence of the motives for pure, and the needs of applied, research.Key words: alkene, polymerization, Ziegler, catalysis, carbocationic, titanium.
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Wang, Aihui, Hui Niu, Zongke He et Yang Li. « Thermoreversible cross-linking of ethylene/propylene copolymer rubbers ». Polymer Chemistry 8, no 31 (2017) : 4494–502. http://dx.doi.org/10.1039/c7py00896a.

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A functional olefin comonomer containing furan group was designed and implemented in ethylene/propylene copolymerization catalyzed by a traditional Ziegler–Natta catalyst; thus, controllable design of EP rubber with thermoreversible cross-linking capability was realized in a facile way, making the recycle of synthetic rubber more feasible.
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Chung, T. C., H. L. Lu et S. Hong. « New Polyolefin Elastomers Containing “Reactive” p-Methylstyrene Units : Preparation by Metallocene Catalysts ». Rubber Chemistry and Technology 72, no 2 (1 mai 1999) : 283–98. http://dx.doi.org/10.5254/1.3538801.

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Abstract This paper summarizes the experimental results of three new polyolefin elastomers, i.e., poly(1-octene-co- p-methylstyrene (O-p-MS), poly(ethylene-ter-propylene-ter-p-methylstyrene) (EP-p-MS) and poly(ethylene-ter-1-octene-ter-p-methylstyrene) (EO-p-MS), containing “reactive” p-MS units. Both Ziegler-Natta and metallocene catalysts were used in studying co- and ter-polymerization reactions. In the copolymerization of 1-octene and p-MS, Ziegler-Natta catalyst TiCl3/AlEt3 exhibits higher catalyst reactivity to produce high molecular weight O-p-MS copolymers, containing up to 20 mol % p-MS. However, the copolymers show very broad composition and molecular weight distributions. On the other hand, two EP-p-MS and EO-p-MS terpolymers with narrow molecular weight and composition distributions were prepared by [C5Me4(SiMe2NtBu)]TiCl2 metallocene catalyst with constrained ligand geometry. The sharp glass transition temperature (Tg) with flat baseline in each differential scanning calorimetry (DSC) curve indicates homogeneous terpolymer microstructures. The Tg of EP-p-MS is very sensitive to the terpolymer composition (ethylene/propylene ratio and p-MS content). In the compositions with ideal ethylene/propylene ratio ∼ 55/45, the Tα is almost proportional to the content of p-MS. Only with the concentration of p-MS &lt; 2 mol %, does the EP-p-MS show alow Tg&lt;−45°C. On the other hand, the EO-p-MS system exhibits a low Tg&lt;−50°C in a wide range of copolymer compositions, even ones with relatively high p-MS contents (&lt; 7 mol %).
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Puhakka, Eini, Tuula T. Pakkanen et Tapani A. Pakkanen. « Theoretical investigations on Ziegler-Natta catalysis : Alkylation of the TiCl4 catalyst ». Journal of Molecular Catalysis A : Chemical 120, no 1-3 (juin 1997) : 143–47. http://dx.doi.org/10.1016/s1381-1169(96)00433-5.

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Infante-Martínez, Ramiro, Enrique Saldívar-Guerra, Odilia Pérez-Camacho et Maricela García-Zamora. « Ethylene Polymerization via Metallocenes : An Experimental Study ». MRS Proceedings 1767 (2015) : 11–16. http://dx.doi.org/10.1557/opl.2015.221.

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ABSTRACTAn experimental study oriented to gather kinetic modelling data in the ethylene polymerization via metallocenes is reported. Also is illustrated the employment of two methods for determination of kinetic behavior and the instantaneous activity of Ziegler-Natta catalysts in the slurry polymerization of ethylene. The theoretical basis for both methods is described as well as the required instrumentation for its implantation at a laboratory level. An experimental program of polymerization with two different metallocenic systems was executed, showing that the direct (measurement of ethylene flow) as well as the calorimetric method (based on energy balances) give equivalent high quality information on the kinetic performance of the catalyst.
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Gholami, Yaghoob, Majid Abdouss, Sadegh Abedi, Farhad Azadi, Pezhman Baniani et Maryam Arsalanfar. « An Investigation on Polymerization of Ethylene by Ziegler-Natta Catalyst in the Presence of a Promoter : Polymerization Behavior and Polymer Microstructure ». Bulletin of Chemical Reaction Engineering & ; Catalysis 13, no 3 (4 décembre 2018) : 412. http://dx.doi.org/10.9767/bcrec.13.3.1574.412-419.

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The effect of a halocarbon (ethyl chloride) as a promoter on a Ziegler-Natta catalyst composed of‌ T‌iCl4 (catalyst), AlEt3 (activator) and Mg(OEt)2 (support) in the polymerization of ethylene have been investigated. In addition, the impact of this compound on the structural and thermal properties of the produced polyethylene has been studied. The catalyst activity and polymerization rate increased almost up to twice when a suitable molar ratio of ethyl chloride to triethylaluminum (TEA) was used. There was no change in the type of the profile of the polymerization rate during the polymerization time. A reduction in the polymer molecular weight was observed in the presence of the promoter and hydrogen. In addition, the MWD curve shifted toward lower values in the presence of ethyl chloride. Furthermore, a numerical method was used to obtain the most probable chain-length distribution, number average molecular weight and weight fraction corresponding to each site type in the presence and absence of the promoter. Since, the catalyst had an irregular shape, the produced polymer also showed a similar morphology. In addition, the promoter used in the polymerization did not have any effect on the produced polymer morphology. The DSC results indicated that the presence of the promoter in the polymerization led to a decrease in the melting point of the produced polymer; whereas, there were no remarkable changes in the crystallization temperature of the polymers. Copyright © 2018 BCREC Group. All rights reservedReceived: 2nd October 2017; Revised: 5th April 2018; Accepted: 26th April 2018How to Cite: Gholami, Y., Abdouss, M., Abedi, S., Azadi, F., Baniani, P., Arsalanfar, M. (2018). An Investigation on Polymerization of Ethylene by Ziegler-Natta Catalyst in the Presence of a Promoter: Polymerization Behavior and Polymer Microstructure. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (3): 412-419 (doi:10.9767/bcrec.13.3.1574.412-419)Permalink/DOI: https://doi.org/10.9767/bcrec.13.3.1574.412-419
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Raj, K. Vipin, et Kumar Vanka. « Understanding Ziegler–Natta catalysis through your laptop ». Resonance 22, no 11 (novembre 2017) : 1025–37. http://dx.doi.org/10.1007/s12045-017-0569-8.

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Endo, Kiyoshi, et Takayuki Otsu. « Polymerization of vinylcyclohexane with ziegler–natta catalyst ». Journal of Polymer Science Part A : Polymer Chemistry 30, no 4 (30 mars 1992) : 679–83. http://dx.doi.org/10.1002/pola.1992.080300420.

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Malizia, Federica, Anna Fait et Giuseppe Cruciani. « Crystal Structures of Ziegler-Natta Catalyst Supports ». Chemistry - A European Journal 17, no 49 (3 novembre 2011) : 13892–97. http://dx.doi.org/10.1002/chem.201101900.

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47

Monji, Majid, Saeed Pourmahdian, Mohammad Vatankhah et Faramarz Afshar Taromi. « Synthesis of highly improved Ziegler-Natta catalyst ». Journal of Applied Polymer Science 112, no 6 (15 juin 2009) : 3663–68. http://dx.doi.org/10.1002/app.29786.

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Marques, Maria de Fatima, Lidiane Almeida et Kamilla Cruz. « Influence of the Preparation Technique of MgCl2/TiCl4 Ziegler-Natta Catalyst on the Performance in Ethylene and Propylene Polymerization ». Chemistry & ; Chemical Technology 4, no 4 (15 décembre 2010) : 291–96. http://dx.doi.org/10.23939/chcht04.04.291.

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Different methods to remove the alcohol of adduct MgCl2nEtOH were studied to obtain Ziegler-Natta catalysts for evaluation in ethylene and propylene polymerization. Thus, the adduct MgCl2nEtOH was submitted to thermal dealcoholation, as well as chemical dealcoholation with different substances: titanium tetrachloride, triethylaluminum, and dichloro-dimethylsilane. Thermogravimetric analyses (TGA) were performed to obtain information on the thermal characteristics of adducts and prepared supported catalysts. Ethylene and propylene homopolymerization were carried out with the prepared catalysts and the polymers were characterized.
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Lenz, Robert W., John Yang, Bin Wu, C. Jeff Harlan et Andrew R. Barron. « Chemical synthesis of poly(β-hydroxybutyrate) by the polymerization of (R,S)-β-butyrolactone with aluminoxane catalysts ». Canadian Journal of Microbiology 41, no 13 (15 décembre 1995) : 274–81. http://dx.doi.org/10.1139/m95-197.

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Racemic β-butyrolactone can be polymerized to crystalline polymers of reasonably high molecular weight by the use of aluminoxane catalysts. Investigations in this and other laboratories have shown that these polymers can be fairly highly isotactic, and in that form they are closely related in structure and physical properties to a reserve polyester produced by many bacteria: poly(β-hydroxybutyrate). In the present investigation, Ziegler–Natta type aluminoxane catalyst systems and a new aluminoxane derivative, tert-butylaluminoxane, were evaluated in attempts to polymerize racemic β-butyrolactone in higher yields to polymers of higher molecular weight and higher stereoregularity. The addition of group 4 metallocenes as cocatalysts for both methylaluminoxane and iso-butylaluminoxane catalysts gave higher yields of the isotactic polymer than those obtained with these catalysts alone, but surprisingly, the tert-butylaluminoxane catalysts produced predominantly syndiotactic rather than isotactic polymers.Key words: poly(β-hydroxybutyrate), β-butyrolactone, aluminoxane catalysts, isotactic poly(β-hydroxybutyrate), syndiotactic poly(β-hydroxybutyrate).
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Braunschweig, Holger, Mario Kraft, Krzysztof Radacki et Sascha Stellwag. « Piperidino Substituted [1]Borametallocenophanes. Synthesis, Reactivity, and Structure ». Zeitschrift für Naturforschung B 61, no 5 (1 mai 2006) : 509–16. http://dx.doi.org/10.1515/znb-2006-0503.

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ansa-Metallocenes and related complexes have considerable potential as catalyst precursors in the Ziegler-Natta type olefin polymerization. In the present paper we report about the synthesis of piperidinyl-substituted [1]borametallocenophanes of titanium and zirconium. Furthermore, the first example of a base stabilized alkyl-substituted [1]borazirconocenophane was fully characterized and tested for its properties in the polymerization of ethene.
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