Highly active peroxides in the radical polymerization of ethylene under high pressure — conversion and initiator usage

Luft, Gerhard; Grimm, H.J.; Dorn, Max

doi:10.1002/apmc.1990.051740114

Cited by 5 publications

(1 citation statement)

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“…During the production of low-density polyethylene (LDPE), attempts have been made to reduce the temperature at which the polymerisation reaction is initiated by using highly active organic peroxides such as tert-butyl peroxyneodecanoate, di-(2-ethyl-hexyl) peroxydicarbonate or di-(2-neodecanoyl peroxyisopropyl)benzene 1) , the aim being to achieve a wider range of product characteristics and higher reaction yields. Problems are caused by the fact that these highly active peroxides are difficult to handle during transportation, storage and metering into the polymerisation reactor.…”

Section: Introductionmentioning

confidence: 99%

Activation of the decomposition oftert-butyl peroxypivalate with trialkylaluminium compounds

Luft¹,

Kessler

Zeiss³

1998

Angew. Makromol. Chem.

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Section: Introductionmentioning

confidence: 99%

Activation of the decomposition oftert-butyl peroxypivalate with trialkylaluminium compounds

Luft¹,

Kessler

Zeiss³

1998

Angew. Makromol. Chem.

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Peroxides and Peroxide Compounds, Organic Peroxides

Sánchez

Myers

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Organic peroxides are compounds possessing one or more oxygen–oxygen bonds that are thermally and photolytically sensitive to facile homolytic cleavage. Thermal decomposition rates are affected by the structure of the organic peroxide and the decomposition conditions. The initially formed free radicals from the oxygen–oxygen bond homolysis are reactive intermediates which quickly undergo a variety of subsequent reactions to form stable products. Thermolysis of organic peroxides is used commercially to initiate free‐radical reactions, eg, halogenation, vinyl monomer polymerization, unsaturated resin cure, polyolefin cross‐linking and rheology modification. Many organic peroxides also undergo reactions in which free radicals are not involved, eg, heterolyses, hydrolyses, reductions, and rearrangements. This article reviews the physical and chemical properties, synthetic methods, and the principal commercial uses of organic peroxides of the following classes: hydroperoxides, dialkyl peroxides, α‐oxygen‐substituted hydroperoxides and dialkyl peroxides, ozonides, peroxyacids, diacyl peroxides, and alkyl peroxyesters. Class discussions cover the broad structural variation that is possible, including organomineral and polymeric derivatives when appropriate. Emphasis is placed on the relationship between peroxide structure and reactivity (thermal stability). Physical hazards associated with organic peroxide manufacture, handling, storage, transportation, and use are discussed. An overview of health hazards associated with handling of organic peroxides is presented.

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Highly active peroxides in the radical polymerization of ethylene under high pressure. Properties of the polymers

Luft

Dorn²

1991

Angew. Makromol. Chem.

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Using highly active peroxide initiators, a number of polyethylene samples were prepared at low temperatures of 70-140°C and a pressure of 1900 bar. The average molecular weight and the melt flow index were adjusted by adding propionaldehyde as modifier. The characteristic properties of the samples as regards the molecular weight distribution, the average molecular weight, the frequency of long chain branching, the crystallinity and the density were determined.As expected, the polymers are characterized by density values of more than 0.955 g/ml and crystallinity values of 65 -80% which are characteristic of PE-HD. The molecular weight distribution, too, remains within narrow limits. On the other hand, rather surprisingly, a relatively high frequency of long chain branching typical of PE-LD is obtained.The investigation of the phase behaviour has shown that polymerization under high pressure at temperatures above 11 5 -11 8 "C takes place in the homogeneous range. The samples polymerized in the transition zone between the single and the two phase area exhibit maximum crystallinity and melt enthalpy. The frequency of long chain branching passed through a minimum. ZUSAMMENFASSUNG: Durch Einsatz von hochaktiven Peroxidinitiatoren wurde eine Reihe von Polyethylenproben bei niedrigen Temperaturen von 70 bis 140 "C und einem Druck von 1900 bar hergestellt. Mittleres Molekulargewicht und Schmelzindex wurden durch Zusatz von Propionaldehyd als Molmassenregler eingestellt. Die Proben wurden hinsichtlich der Molekulargewichtsverteilung, mittleren Molekulargewichte, Langkettenverzweigungsfrequenz, Kristallinitat und Dichte charakterisiert. 0 1991 Huthig & Wepf Verlag, Base1 CCC 0003-3146/91/%03.00 177 G. Luft and Max Dorn Wie erwartet zeichnen sich die Polymeren durch hohe Dichten von iiber 0,955 g/ml und Kristallinitaten von 65 bis 8O%, wie sie fiir PE-HD charakteristisch sind, aus. Auch die Molekulargewichtsverteilungen sind eng. Andererseits fiillt eine relativ hohe Langkettenverzweigungsfrequenz, wie sie fur das PE-LD typisch ist, auf. Die Untersuchung des Phasenverhaltens ergab, da8 die Polymerisation unter dem hohen Druck bei Temperaturen oberhalb 115 bis 118°C im homogenen Bereich ablauft. Die hochsten Werte von Kristallinitat und Schmelzenthalpie zeigten die im ubergangsbereich zwischen Ein-und Zweiphasengebiet polymerisierten Proben. Die Langkettenverzweigungsfrequenz durchlief hier ein Minimum.

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Highly active peroxides in the radical polymerization of ethylene under high pressure — conversion and initiator usage

Cited by 5 publications

References 2 publications

Activation of the decomposition oftert-butyl peroxypivalate with trialkylaluminium compounds

Activation of the decomposition oftert-butyl peroxypivalate with trialkylaluminium compounds

Peroxides and Peroxide Compounds, Organic Peroxides

Highly active peroxides in the radical polymerization of ethylene under high pressure. Properties of the polymers

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