Coordination Polymerization

Soares, João B. P.; Simon, Leonardo C.

doi:10.1002/9783527619870.ch8

Cited by 13 publications

(5 citation statements)

References 59 publications

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“…Polypropylene is undoubtedly one of the most robust material fields in the polyolefin production and consumption market globally [15][16][17][18], with a current annual demand of about 56 million tons in 2016 [19]. They are used in a wide range of applications ranging from packaging to lightweight engineering plastics for automobile, electrical and electronics, construction, medical, equipment, and facilities industries [20,21].…”

Section: Introductionmentioning

confidence: 99%

Toughened High-Flow Polypropylene with Polyolefin-Based Elastomers

Wang

Guo

et al. 2019

Polymers

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Polyolefin is the most widely used and versatile commodity polymer. In this work, three types of polyolefin-based elastomers (PBEs) were adopted to toughen a high-flow polypropylene to improve its overall performance. The chain microstructures of these PBEs, including ethylene/1-octene (E/O) random copolymer from Dow Chemical s polyolefin elastomer (POE), olefin block copolymers (OBCs) of E/O from Dow, and ethylene/propylene random copolymer from ExxonMobil's propylene-based elastomer, were elucidated by GPC, 13 C NMR, TREF, and DSC techniques. The mechanical, thermal and optical properties, and morphology analysis of the PP/PBE blends were also studied to investigate the toughening mechanism of these PBEs. The results showed that all three types of PBEs can effectively improve the Izod impact strength of the PP/PBE blends by the addition of the rubber compositions, at the cost of the stiffness. PBE-1 and PBE-2 were found to have a great stiffness-toughness balance with about 1700 MPa of flexural modulus, about 110 • C of HDT and 3.6 kJ/m 2 of impact strength on the prepared PP/PBE blends by forming separated rubber phase and refined spherulite crystals. As a result, the OBC with alternating hard and soft segments could achieve a similar toughening effect as the E/P random copolymer. Surprisingly, no obvious rubber phase separation was observed in the PP/PBE-4 blend, which might be due to the good compatibility of the E/P random chains with the isotactic PP; therefore, the PP/PBE blend obtains great toughness performance and optical transparency with the highest Izod impact strength of 4.2 kJ/m 2 and excellent transparency. 22 million tons. Due to rapid market expansion of takeout for dining box and automobile industries in China, the high-flow homo polypropylene market has also witnessed a dramatic increase to about above 600 kilotons annually in the recent few years.Although the high-flow homo polypropylene with high melting index (typically above 50 g/10 min) and good processability possesses high flexural modulus, the impact strength is relatively low compared to the ethylene/propylene copolymer and easily suffers from brittle fracture [22]. In order to solve this problem, two approaches are typically adopted to improve the overall performance of the polymer. One alternative is to introduce an extra operation line for the incorporation of a small amount of ethylene into the isotactic chain in the PP production facility, and the other method is to make post-modifications of the high-flow polypropylene by blending elastomer with PP, and glass fibers for automobiles [23][24][25].The Polyolefin-based elastomers (PBEs) have received considerable attention because of their low density, recycling potential, better chemical resistance, processing advantages, and good resilience without permanent deformation. Unlike rubber, they do not require vulcanization. In addition, the low cost together with the wide availability of ethylene, propylene and α-olefin monomers makes the polyolefin-based elastomers more desirable. T...

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Section: Introductionmentioning

confidence: 99%

Toughened High-Flow Polypropylene with Polyolefin-Based Elastomers

Wang

Guo

et al. 2019

Polymers

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“…The free radical way, discovered in the 1930s by Imperial Chemical Industries (ICI), produces low-density polyethylene (LDPE). This synthesis requires very harsh polymerization conditions: high temperatures ( T ≈ 300 °C) and high pressures ( P Ethylene > 2000 bar). − The obtained polymer is highly branched, thus leading to a low-density and low-crystallinity material. The other route, a catalytic process discovered by Ziegler and Phillips Petroleum in the 1950s, yields high-density polyethylene (HDPE): a very linear PE with very high crystallinity.…”

Section: Introductionmentioning

confidence: 99%

“…The other route, a catalytic process discovered by Ziegler and Phillips Petroleum in the 1950s, yields high-density polyethylene (HDPE): a very linear PE with very high crystallinity. By copolymerizing ethylene with α-olefins such as 1-butene or 1-hexene, a slightly branched PE is obtained, named LLDPE for linear low-density polyethylene. , LLDPE exhibits an intermediate crystallinity between LDPE and HDPE.…”

Section: Introductionmentioning

confidence: 99%

Free Radical Emulsion Polymerization of Ethylene

et al. 2014

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Free radical polymerization of ethylene in aqueous media was performed under mild conditions (T < 90 °C and P ethylene < 250 bar) using an anionic initiating (ammonium persulfate, APS) and stabilizing (sodium dodecyl sulfate, SDS) system, yielding polyethylene latexes. pH regulation was a key to the feasibility of this process. Particle sizes and morphologies as well as polymerization yields were affected by SDS concentration. In any case, yields increased with polymerization time, especially in presence of surfactant. When increasing the polymerization pressure, the increase on yields was much stronger in presence of surfactant and particle sizes increased more when no surfactant was used. Stable polyethylene latexes with relatively high

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“…A quantitative model for the polymerization kinetics of α-olefins with coordination catalysts is essential for the design and optimization of polymerization reactors . While many publications have proposed fundamental and empirical models for α-olefin polymerization kinetics with coordination catalysts, several aspects of these systems are still poorly quantified. − Among these still controversial subjects are the hydrogen effect on the polymerization kinetics of propylene − and ethylene − and the rate enhancement of ethylene polymerization by α-olefins. − …”

Section: Introductionmentioning

confidence: 99%

Ethylene Polymerization and Ethylene/1-Octene Copolymerization with rac-Dimethylsilylbis(indenyl)hafnium Dimethyl Using Trioctyl Aluminum and Borate: A Polymerization Kinetics Investigation

et al. 2013

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The polymerization of ethylene and ethylene/1-octene in a semibatch solution reactor using rac-dimethylsilylbis(indenyl)hafnium dimethyl and tetrakis(pentafluorophenyl) borate dimethylanilinium salt ([B(C6F5)4]−[Me2NHPh]+) as the catalytic system and trioctylaluminum (TOA) as the scavenger was investigated. Ethylene and 1-octene concentrations, polymerization temperature, borate/catalyst ratio, and TOA concentration were changed to study the ethylene polymerization kinetics with this system. The mode of addition for catalyst, borate, and TOA was also studied. When TOA and borate were added sequentially to the reactor followed by the catalyst, the polymerization activity was low and the molecular weight distribution (MWD) bimodal. Contrarily, when TOA was added first to the reactor and a mixture of catalyst and borate were added to the reactor, the polymerization rate was much higher and the MWD unimodal. An augmented 2 × 2 central composite design was used to investigate this phenomenon. Borate helped stabilize the active sites and reduce potential deactivation reactions with excess TOA.

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Coordination Polymerization

Cited by 13 publications

References 59 publications

Toughened High-Flow Polypropylene with Polyolefin-Based Elastomers

Toughened High-Flow Polypropylene with Polyolefin-Based Elastomers

Free Radical Emulsion Polymerization of Ethylene

Ethylene Polymerization and Ethylene/1-Octene Copolymerization with rac-Dimethylsilylbis(indenyl)hafnium Dimethyl Using Trioctyl Aluminum and Borate: A Polymerization Kinetics Investigation

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