High‐conversion diffusion‐controlled polymerization of styrene. I

Marten, F. L.; Hamielec, A. E.

doi:10.1002/app.1982.070270213

Cited by 148 publications

(97 citation statements)

References 26 publications

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“…A p and A t are the parameters that govern the rate at which propagation and termination rates decrease in the diffusion controlled regions. R D is the reaction-diffusion parameter, which is defined as the termination kinetic constant in the reaction-diffusion region divided by the product of the propagation kinetic constant and the instantaneous unreacted monomer concentration M [18,19,30,31,29].…”

Section: ͑6͒mentioning

confidence: 99%

“…In these equations f m v and f p v are the fractional free volumes of pure monomer and pure polymer, respectively (where "pure" refers to the values obtained in the absence of any other material components), ␣ m and ␣ p are the thermal coefficients of expansion, T gm and T gp are their glass transition temperatures, f Tgm and f Tgp represent their fractional free volumes at the glass transition temperatures, and T (K) represents the local temperature [18,19,[30][31][32]. m is the volume fraction of monomer, which decreases during polymerization [15,16,33].…”

Section: ͑6͒mentioning

confidence: 99%

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Nonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions Part I Modeling

2009

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Section: ͑6͒mentioning

confidence: 99%

Section: ͑6͒mentioning

confidence: 99%

Nonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions Part I Modeling

2009

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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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“…[24][25][26][27][28][29][30] U tu svrhu provedena je dinamička simulacija rada polimerizacijskog šaržnog reaktora primjenom programskog sustava Chem-CAD v. 5.4. (2004.…”

Section: Ključne Riječi Stiren Polimerizacija U Otopini Difunkcijskunclassified

Dinamička simulacija rada šaržnog polimerizacijskog reaktora i parametarska analiza homopolimerizacije stirena

Jukić

2015

Kem. Ind.

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UvodOd sedamdesetih godina 20. stoljeća, kada se polimerno reakcijsko inženjerstvo počelo razvijati kao znanstvena disciplina, i matematičko modeliranje polimerizacijskih reaktora postalo je vrlo detaljno i opsežno.1,2 Za razvoj prikladnog matematičkog modela nužno je poznavanje kinetike i reakcijskog mehanizma kojim se odvija proces polimerizacije, zatim konfiguracije polimernog reaktora i radnih uvjeta kako bi se predvidio njihov utjecaj na građu sintetiziranih makromolekula (na primjer, raspodjelu molekulskih masa, stupanj cijepljenja i drugo) kao i morfologiju polimernog proizvoda (na primjer, raspodjelu veličine čestica, poroznost i drugo). Kod polimerizacijskih procesa kvaliteta proizvoda vrlo je kompleksno pitanje jer o strukturnim i morfološkim karakteristikama polimera ovise njihova fizikalna, kemijska, toplinska, reološka i mehanička svojstva, pa tako i krajnja primjena. U današnje vrijeme računalni programi za simulaciju (engl. Computer-Aided Design, CAD) rada polimerizacijskih reaktora smatraju se jednim od vrlo uspješnih alata koji znatno pridonose razvoju procesnih tehnologija kao i proizvodnji polimera. 2,3To uključuje projektiranje procesa, optimizaciju, procjenu parametara stanja i vođenje procesa. Stabilnost i vođenje rada polimerizacijskih reaktora mogu se preliminarno ispitati i provjeriti prije izgradnje postrojenja upotrebom dinamičkih reaktorskih modela. Takvi modeli mogu identificirati potencijalne izvore koji uzrokuju varijacije u kvaliteti proizvoda te ih svesti na najmanju mjeru, a bitni su i za razvoj odgovarajuće računalne podrške pri vođenju takvih procesa.4-7 Najznačajniju ulogu u razvoju polimerizacijskih procesa i proizvoda imaju procesni inženjeri jer njihovo dugogodišnje iskustvo i znanje o procesu kao i o modeliranju i programiranju znatno pridonosi stvaranju visokokvalitetnih proizvoda. Do danas je razvijeno nekoliko komercijalnih programskih paketa za simuliranje raznih polimerizacijskih procesa, a prvi takav bio je POLYRED, razvijen na sveučilištu Wisconsin. Prema mehanizmu rasta lanca i kinetici, reakcije polimerizacije razvrstavaju se u dvije velike skupine: stupnjevite ili postupne te lančane, koje se mogu odvijati radikalskim, ionskim i koordinativnim mehanizmom. Procesi lančanih radikalskih polimerizacija temeljni su i najviše upotrebljavani tehnološki postupci dobivanja polimernih materijala, a odvijaju se klasičnim mehanizamom radikalskih lančanih reakcija u kojemu su zastupljena najmanje tri stupnja elementarnih reakcija: inicijacija, propagacija i terminacija. Radikalskim mehanizmom polimerizira najveći broj vinilnih, dienskih, akrilatnih i metakrilatnih monomera stvarajući odgovarajuće homopolimere i velik broj kopolimera. Sažetak Provedena je dinamička simulacija rada šaržnog polimerizacijskog reaktora za proces homopolimerizacije stirena u otopini ksilena iniciranog uz monofunkcijski i difunkcijski peroksidni inicijator. Monofunkcijski inicijator ima široku industrijsku primjenu, dok je difunkcijski u preliminarnim istraživanjima pokazao određene prednosti kao š...

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High‐conversion diffusion‐controlled polymerization of styrene. I

Cited by 148 publications

References 26 publications

Nonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions Part I Modeling

Nonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions Part I Modeling

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

Dinamička simulacija rada šaržnog polimerizacijskog reaktora i parametarska analiza homopolimerizacije stirena

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