Kinetics of polymerization initiated by peroxides containing heterocyclic groups. I. Kinetics of bulk polymerization of styrene and vinyl acetate initiated by difuroyl peroxide

Molnár, Sándorné

doi:10.1002/pol.1972.150100805

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…In eqs 2 and 3, k t is the termination rate constant and R i is the total rate of initiation, which is the sum of the thermal initiation R i ,th of styrene and the initiation due to the decomposition of BPO with a rate constant k BPO and an efficiency f ‘. The values of R i ,th and 2 f ‘ k BPO obtained here are reasonably comparable to the literature values: R i ,th = 2.5 × 10 -9 mol L -1 s -1 1 8 and k BPO = 3.5 × 10 -5 s -1 . In this work, use is made of the k p value recommended by IUPAC 20 and the k p 2 / k t value due to Hui and Hamielec ( k p = 660 and k p 2 / k t = 1.71 × 10 -3 L mol -1 s -1 , respectively).…”

Section: Resultssupporting

confidence: 86%

“…The values of R i,th and 2f′ k BPO obtained here are reasonably comparable to the literature values: R i,th ) 2.5 × 10 -9 mol L -1 s -1 1 8 and k BPO ) 3.5 × 10 -5 s -1 . 19 In this work, use is made of the k p value recommended by IUPAC 20 and the k p 2 /k t value due to Hui and Hamielec 18 (k p ) 660 and k p 2 /k t ) 1.71 × 10 -3 L mol -1 s -1 , respectively).…”

Section: Resultsmentioning

confidence: 99%

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Mechanism and Kinetics of Iodide-Mediated Polymerization of Styrene

1998

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The kinetics of the bulk polymerization of styrene in the presence of a model ω-polystyryl iodide (M n ≈ 2000, and M w/M n ≈ 1.26) as mediator and benzoyl peroxide as initiator was studied. The rate of polymerization, R p, was found to be independent of the iodide concentration, showing that the stationary concentration of polymer radicals, [P*], is determined by the balance of initiation and termination rates, as in the conventional (iodide-free) system. The pseudo-first-order activation rate constant k act of the model iodide was determined as a function of BPO concentration and temperature (50−80 °C) by both the GPC curve-resolution and polydispersity-analysis methods. The results showed that k act is directly proportional to [P*], which means that degenerative transfer (active species-exchanging transfer) is the only important mechanism of activation in this system. The activation energy for the transfer rate constant k ex was found to be 27.8 kJ mol-1, somewhat smaller than the known activation energy for the styrene propagation rate constant k p of 32.5 kJ mol-1. This indicates that lowering, rather than raising, the reaction temperature will be more effective in preparing polystyrenes with a narrower polydispersity by the iodide-mediated polymerization. This is because the most important parameter for determining the polydispersity of a degenerative-transfer-type system is the k ex/k p ratio, as has been known for some time.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Mechanism and Kinetics of Iodide-Mediated Polymerization of Styrene

1998

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“…Rate Constants. The parameters used in this work are listed in Table , where k i,th and k i,BPO are the rate constant of thermal initiation and that of the initiation due to BPO decomposition (with the initiation efficiency included). The initiation rate R i , which is assumed here to be constant, is given by with [M] 0 = 7.7 M and [BPO] 0 = 4.7 mM or zero in this study.…”

Section: Resultsmentioning

confidence: 99%

Quantitative Comparison of Theory and Experiment on Living Radical Polymerization Kinetics. 1. Nitroxide-Mediated Polymerization

2002

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The kinetic theories on the polymerization rate and polydispersity for the persistent radical-mediated living radical polymerization were quantitatively tested by experiments for the bulk polymerization of styrene with PS-DEPN with or without BPO at 80 °C, where PS is polystyrene, DEPN is N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, and BPO is benzoyl peroxide. For the BPO-free system, experiments agreed with the theories on an absolute scale, showing a 2/3-order time dependence of conversion index and a 3/8 k d-dependent time evolution of polydispersity index, where k d is the dissociation rate constant. It was also experimentally demonstrated for the first time that the conventional initiation can not only increase the conversion but also lower the polydispersity at a given polymerization time t (at least when t is small), as was predicted by the theories.

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“…In general, the aim seems to be to favor the normal (trifunctional) grafting, while minimizing crosslinking.2-6 Many experimental works have been published on the synthesis and characterization of HIPS.2-21 The simpler bulk homopolymerization of St (without rubber) has also been extensively studied. [22][23][24][25][26][27] In spite of its industrial importance, only relatively crude mathematical models on the HIPS synthesis have been p~b l i s h e d .~' -~~ In L udwico and Rosen 35,36 grafting reactions were neglected, but the partition of monomer and initiator between phases is taken into consideration to calculate the global polymerization rate. Except for these publications, all others (including the present) treat the bulk process as if it were homogeneous.…”

Section: Introductionmentioning

confidence: 99%

Bulk polymerization of styrene in presence of polybutadiene: Calculation of molecular macrostructure

Estenoz

Valdez

Oliva

et al. 1996

J. Appl. Polym. Sci.

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SYNOPSISIn our previous publication the detailed molecular macrostructure generated in a solution polymerization of styrene (St) in the presence of polybutadiene (PB) at 6OoC, was theoretically calculated. In this work, an extended kinetic mechanism that incorporates monomer thermal initiation, chain transfer to the rubber, chain transfer to the monomer, and the gel effect is proposed, with the aim of simulating a bulk high-impact polystyrene (HIPS) process. The mathematical model enables the calculation of the bivariate weight chainlength distributions (WCLDs) for the total copolymer and for each of the generated copolymer topologies and the univariate WCLDs for the free polystyrene (PS), the residual PB, and the crosslinked PB topologies. These last topologies are characterized by the number of initial PB chains per molecule; copolymer topologies are characterized by the number of PS and PB chains per molecule. The model was validated with published literature data and with new pilot plant experiments that emulate an industrial HIPS process. The literature data correspond to a dilute solution polymerization at a constant low temperature with chemical initiation and a bulk polymerization at a constant high temperature with thermal initiation. The new experiments consider different combinations of prepolymerization temperature, initiator concentration, and solvent concentration. One of the main conclusions is that most of the initial PB is transformed into copolymer. For example, for a prepolymerization temperature of 12OOC with addition of initiator, the experimental measurements indicate that the final total rubber mass is approximately three times higher than the initial PB. Also, according to the model predictions, the final weight fractions are: free PS, 0.778; graft copolymer, 0.220; initial PB, 0.0015; and purely crosslinked PB, 0.0005. The final graft copolymer exhibits the following characteristics: average molecular weights, Mn,c = 492,000 and Mw,c = 976,000; average weight fraction of St, 0.722; and average number of PS and PB branches per molecule, 5.19 and 1.13, respectively. 0 1996JohnWiley & Sons, Inc.

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Kinetics of polymerization initiated by peroxides containing heterocyclic groups. I. Kinetics of bulk polymerization of styrene and vinyl acetate initiated by difuroyl peroxide

Cited by 10 publications

References 17 publications

Mechanism and Kinetics of Iodide-Mediated Polymerization of Styrene

Mechanism and Kinetics of Iodide-Mediated Polymerization of Styrene

Quantitative Comparison of Theory and Experiment on Living Radical Polymerization Kinetics. 1. Nitroxide-Mediated Polymerization

Bulk polymerization of styrene in presence of polybutadiene: Calculation of molecular macrostructure

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