Continuous Oxygen-Initiated Ethylene Polymerization

Grimsby, F. Norman; Gilliland, E. R.

doi:10.1021/ie50583a041

Cited by 12 publications

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“…The time conversion curves clearly showed that the initiator system had an approximately 50-min induction period (Figure a)), which was another evidence that the polymerization proceeded through a radical mechanism with the help of oxygen. It is a typical phenomenon that a radical polymerization assisted by oxygen has a significant induction period. − Plots of −ln(1 − X ), where X is the fractional conversion, as a function of time resulted in linear relationships (Figure b)), revealing that the present initiator system follows first-order kinetics with respect to monomer concentration. From the slope of these lines, the polymerization rate constant ( k ) at each temperature was determined.…”

Section: Resultsmentioning

confidence: 90%

“…It is a typical phenomenon that a radical polymerization assisted by oxygen has a significant induction period. [20][21][22][23] Plots of -ln(1 -X), where X is the fractional conversion, as a function of time resulted in linear relationships (Figure 3b)), revealing that the present initiator system follows first-order kinetics with respect to monomer concentration. From the slope of these lines, the polymerization rate constant (k) at each temperature was determined.…”

Section: Activity Of Nabh 4 For the Emulsion Polymerization Of Styrenementioning

confidence: 99%

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First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H₂O

Jang¹,

Choi²,

Kim³

2004

Langmuir

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Emulsion polymerization of styrene with sodium borohydride (NaBH4) in an aqueous sodium dodecyl sulfate (SDS) solution was successfully accomplished for the first time. Polystyrene with a high molecular weight (M w > 2 000 000) and a broad molecular weight distribution (MWD ≈ 3.5) was obtained in a conversion of less than 30%. Several pieces of evidence that the polymerization proceeded through radical intermediates were observed. Variations in the concentration of NaBH4 showed a critical range in said concentration, i.e., a borderline that determined whether the main reaction was directed to either a polymerization or a competed reaction with variations in the NaBH4 level. Kinetic studies on the emulsion polymerization of styrene with NaBH4 performed at 50, 55, and 60 °C showed that the initiator had an approximately 50-min induction period. A plot of −ln(1 − X), where X is the fractional conversion, as a function of time resulted in a linear relationship, showing that the present initiator system followed first-order kinetics with respect to monomer concentration. The Arrhenius plot between ln k vs 1/T gave a good linear relation, and the overall activation energy was observed to be about 37.5 kcal/mol. The employment of CH3I with NaBH4 significantly increased conversion (>95%) and provided polystyrene with a well-controlled M w and MWD (<2.3).

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Section: Resultsmentioning

confidence: 90%

Section: Activity Of Nabh 4 For the Emulsion Polymerization Of Styrenementioning

confidence: 99%

First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H₂O

Jang¹,

Choi²,

Kim³

2004

Langmuir

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“…Oxygen has also been reported to act as an initiator. For high-pressure polymerization of ethylene, induction time was observed to decrease with increasing oxygen concentration and temperature. − Grimsby and Gilliland and Schoenemann proposed that an oxygen molecule reacts with an ethylene molecule to produce two free radicals for propagation. Moreover, oxygen in combination with various organometallic chemicals (especially group III) generates high-performance initiators for free-radical polymerization .…”

Section: Introductionmentioning

confidence: 99%

Oxygen-Initiated Free-Radical Polymerization of Alkyl Acrylates at High Temperatures

et al. 2021

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Molecular oxygen has been reported to be a strong inhibitor at low temperatures. Here, it is shown that the introduction of oxygen gas into the free-radical polymerization of n-butyl acrylate (nBA) results in high conversion of the monomer in a very short time at temperatures above 140 °C without the use of any conventional initiators. By conducting first-principles calculations based on density functional theory, this work for the first time identifies and kinetically studies the most-likely reactions via which molecular oxygen contributes to polymer chain initiation. It provides theoretical and experimental evidence that molecular oxygen acts as a catalyst in alkyl acrylate free-radical polymerization at high temperatures. A triplet diradical intermediate is generated from solvated oxygen reacting with an alkyl acrylate monomer. The intermediate then reacts with another monomer and thermally dissociates from molecular oxygen to proceed toward polymerization. This theoretical finding is supported by laboratory experiments showing that in the presence of a very small amount of molecular oxygen and in the absence of any thermal initiators, free-radical polymerization of nBA occurs sustainably and proceeds to a very high monomer conversion. This work opens a new path for a more economic and sustainable production of higher-quality acrylic polymers using molecular oxygen as an initiator catalyst.

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Die Primärschritte der sauerstoffinitiierten Äthylenpolymerisation

Gierth

1970

Angew. Makromol. Chem.

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Die Reaktionen vor und beim Start der sauerstoffinitiierten hhylenpolymerisation wurden bei Temperaturen unter 170 ' C, Driicken bis zu 2 200 at und relativen Sauerstoffkonzentrationen bis zu 75 ppm -bezogen auf Athylen -untersucht. Die Polymerimtion setzt nach Erreichen des Startpunktes plotzlich ein. Er ist eine Folge der Selbstinhibierung der Reaktion durch Sauerstoff. Der primiire Rdikallieferant wird um so leichter gebildet, je hoher der Druck ist. Es mu13 angenommen werden, da13 dieser Stoff rascher zerfiillt, als er gebildet wird. Der Anteil des Sauerstoffs, der in nicht der Initiierung dienenden Nebenreaktionen verbraucht wird, steigt mit der Einsatzkonzentration an. SUMMARY :The reactions before and during the start of the oxygen initiated polymerization of ethylene have been investigated at temperatures less than 170°C, pressures up to 2200 at and oxygen concentrations in feed up to 75 ppm. The reaction sudden& starts when starting point is reached. This is caused by inhibition of the reaction by oxygen itself. The primarily radical delivering compound is formed the easier the higher the pressure is. It must be eaaumed that this compound decomposes more rapidly than it is produced. The amount of oxygen being consumed in not initiating side-reaotions increases with its concentration in feed.

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Continuous Oxygen-Initiated Ethylene Polymerization

Cited by 12 publications

References 5 publications

First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H₂O

First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H₂O

Oxygen-Initiated Free-Radical Polymerization of Alkyl Acrylates at High Temperatures

Die Primärschritte der sauerstoffinitiierten Äthylenpolymerisation

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Continuous Oxygen-Initiated Ethylene Polymerization

Cited by 12 publications

References 5 publications

First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H2O

First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H2O

Oxygen-Initiated Free-Radical Polymerization of Alkyl Acrylates at High Temperatures

Die Primärschritte der sauerstoffinitiierten Äthylenpolymerisation

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First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H₂O

First Emulsion Polymerization of Styrene with Sodium Borohydride: Evidence of the Generation of Radical Intermediates by Sodium Borohydride in H₂O