Effectiveness of Organic Peroxide Initiators in the High-Pressure Polymerization of Ethylene

Luft, Gerhard; Bitsch, Helmut; Seidl, Hildegard

doi:10.1080/00222337708061313

Cited by 51 publications

(31 citation statements)

References 5 publications

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“…As a consequence, DX is lowered toward the highest experimental temperatures, although the propagation rate coefficient, k p , is further enhanced. Such situations of maximum conversion have already been reported [4][5][6] and have been presented in terms of maximum values of initiator productivity, IP, or of minimum values of the initiator demand measures, h or ID.…”

Section: Resultsmentioning

confidence: 89%

“…At higher reactor temperatures, the initiator decomposition rate may become too fast as to allow for perfect micro-mixing of the initiator into the CSTR internal volume. [4][5][6] As a consequence, polymer production reaches a maximum value at an optimum temperature, T opt , and decreases upon further heating. The initiator efficiencies reported and discussed in our study refer to temperatures below T opt where mixing of the initiator into the CSTR is sufficiently fast as compared to initiator decomposition half-life.…”

Section: Resultsmentioning

confidence: 99%

“…[2,3] For the optimization and the design of technical polymerization processes, in addition to decomposition kinetics, the capability of initiating chain growth of the radicals from initiator decomposition needs to be known. Luft et al [4] introduced the specific initiator demand, h, defined as the mass of initiator required for producing a certain mass of polymer. The quantity h, in g Á kg À1 , directly yields the initiator-related production costs.…”

Section: Full Papermentioning

confidence: 99%

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Initiator Efficiency of tert‐Alkyl Peroxyesters in High‐Pressure Ethene Polymerization

Buback

Fischer

Hinrichs

et al. 2007

Macro Chemistry & Physics

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High‐pressure ethene polymerizations using thirteen tert‐alkyl peroxyester initiators, RC(CH3)2OOCOR′ (with R = methyl, ethyl, neo‐pentyl, tert‐butyl and R′ = methyl, i‐propyl, propyl, butyl, tert‐butyl, 2‐heptyl) have been carried out in a CSTR. The initiator efficiency f has been determined for each peroxyester at 2 000 bar over a range of temperatures, partly up to 250 °C. The highest initiator efficiencies, up to about f = 0.9, are observed for tert‐butyl peroxyesters, in which the R' species is a primary radical, as e.g., with tert‐butyl peroxypentanoate and tert‐butyl peroxyacetate. The lowest efficiency value, of about f = 0.37, occurs with tert‐butyl peroxypivalate. The radicals from initiator decomposition, R′COO· and RC(CH3)2O., may undergo β‐scission reactions to produce R′ radicals by decarboxylation and R radicals by “deacetonization”, respectively. In‐cage termination reactions between oxygen‐centered and carbon‐centered radicals essentially control initiator efficiency.magnified image

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Full Papermentioning

confidence: 99%

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Initiator Efficiency of tert‐Alkyl Peroxyesters in High‐Pressure Ethene Polymerization

Buback

Fischer

Hinrichs

et al. 2007

Macro Chemistry & Physics

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“…The large free-radical concentration close to the reactor inlet position favors termination, which is secondorder in free-radical concentration. Enhanced termination of primary or of small oligomeric free radicals lowers DX, although k p grows upon further increasing T. Situations of maximum conversion have already been reported [1][2][3] and have been given in terms of maxima in initiator productivity, IP, or minima in initiator demand, Z or ID. From the maximum value of peroxide-induced ethene conversion, DX opt , at 188 8C (Figure 2b), the extremum values of IP, Z, ID are calculated to be: IP ¼ 1.3 Á 10 5 , Z ¼ 6.1 Á 10 À2 g Á kg À1 , and ID ¼ 2.8 Á 10 À4 mol Á kg À1 .…”

Section: Resultsmentioning

confidence: 99%

“…For the optimal design of technical polymerization processes initiator consumption needs to be known. To characterize initiator performance, Luft et al [1] introduced the specific initiator demand, Z: Z ðin g=kgÞ ¼ applied mass of initiator=mass of polymer produced…”

Section: Introductionmentioning

confidence: 99%

Initiator efficiency of peroxides in high-pressure ethene polymerization

Becker

Buback

Sandmann

2002

Macromol. Chem. Phys.

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Dynamic modeling of multizone, multifeed high-pressure LDPE autoclaves

Pladis

Kiparissides

1999

J. Appl. Polym. Sci.

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A comprehensive mathematical model is developed to simulate the dynamic behavior of multizone, multifeed high-pressure ethylene polymerization autoclaves. To describe the complex flow patterns occurring in low-density polyethylene (LDPE) autoclaves, a user-specified multisegment, multirecycle model representation of the actual multizone reactor is established. A general reaction mechanism is employed to represent the kinetics of ethylene polymerization. Dynamic mass, molar species, and energy balances are derived to predict the polymerization rate, monomer conversion, molecular weight developments (e.g., M n , M w , long-and short-chain branching), and temperature profile with respect to time and spatial position in the reactor. Detailed results on the start-up and grade transition of a four-zone autoclave reactor are presented and the effects of the macromixing parameters (e.g., number of segments per reaction zone and the total and side external recycle ratios) on the dynamic behavior of the reactor are investigated. It is shown that the model macromixing parameters can significantly affect the initiator consumption rate in a reaction zone. The present model is capable of predicting accurately the dynamic behavior of LDPE autoclaves and, thus, can be employed in the design, optimization, and control of these reactors.

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Effectiveness of Organic Peroxide Initiators in the High-Pressure Polymerization of Ethylene

Cited by 51 publications

References 5 publications

Initiator Efficiency of tert‐Alkyl Peroxyesters in High‐Pressure Ethene Polymerization

Initiator Efficiency of tert‐Alkyl Peroxyesters in High‐Pressure Ethene Polymerization

Initiator efficiency of peroxides in high-pressure ethene polymerization

Dynamic modeling of multizone, multifeed high-pressure LDPE autoclaves

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