Crosslinking in Monovinyl Monomers (I). By Chain Transfer With the Polymer Chain

A general statistical theory in direct relation to the kinetics of polymerization is developed for free radical polymerization with chain transfer. In the present paper this relationship is displayed in detail; analytical expressions are-derived for the probabilities of reaction as functions of the reaction rates and the monomer conversion. The statistical treatment (cascade theory) of the polyreaction allows the calculation of the weight average degree of polymerization P,, the z-average mean square radius of gyration (S'),, and the particle scattering factor PZ(Q). While for linear chains the mentioned averages are determined by a single link probability, in the branched system these averages are characterized by a stochastic matrix whose elements are the various link probabilities. The theory is applied to poly(viny1 acetate). A good agreement is obtained with the experimental results of D. J . Stein for this polymer. ZUSAMMENFASSUNG :Es wird eine allgemeine statistische Theorie der radikalischen Polymerisation rnit Ketteniibertragung entwickelt, die in direktem Zusammenhang mit der Polymerisationskinetik steht. Die vorliegende Arbeit befaBt sich im einzelnen mit dieser Beziehung; es werden analytische Ausdriicke fur die Reaktionswahrscheinlichkeiten als Funktion der Reaktionsgeschwindigkeiten und des Monomerumsatzes abgeleitet. Die statistische Behandlung (Kaskadentheorie) der Polyreaktion erlaubt die Berechnung des Gewichtsmittels des Polymerisationsgrads P,, des z-Mittels des mittleren Tragheitsradiusquadrats (S'), und des Streuformfaktors PZ(0). Wahrend fir lineare Ketten die erwahnten Mittelwerte durch eine einzige Verkniipfungswahrscheinlichkeit festgelegt sind, sind die entsprechen-?en Mittelwerte bei dem verzweigten System durch eine stochastische Matrix bestimmt, Leren Elemente die verschiedenen Verkniipfungswahrscheinlichkeiten sind. Die Theorie . ird auf Polyvinylacetat angewendet. Es wird eine gute Ubereinstimmung mit den experiwitellen Ergebnissen von D. J . Stein fur dieses Polymere erhalten.

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“…The functions Z and h are defined as with (7) i, is the wavelength in the solution and 6 the scattering angle.…”

Section: I-ccmentioning

confidence: 99%

Branching in free radical polymerization due to chain transfer. Application to poly(vinyl acetate)

Wolf

Burchard

1976

Makromol. Chem.

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“…Another pathway to crosslinked structures and gel formation is propagation via TDB to branched chains and subsequent termination by combination (see refs. ). As mentioned above, we neglect also all reactions leading to multiple radicals.…”

Section: Resultsmentioning

confidence: 97%

“…To explain this increase of

\overset{true¯}{M_{W}}

at higher conversion a moderate, temperature independent intermolecular chain transfer to polymer with k tr,P / k P = 6 × 10 −5 and subsequent long chain branching from a mid‐chain radical has been assumed. Intermolecular chain transfer to polymer combined with termination by combination may also be a source of crosslinking (and subsequent fouling) as was shown for monomers like vinyl acetate or methyl acrylate …”

Section: Elementary Steps In Nvp Polymerizationmentioning

confidence: 98%

Side Reactions in Aqueous Phase Polymerization of N‐Vinyl‐Pyrrolidone as Possible Source for Fouling

Deglmann

Hellmund

Hungenberg³

et al. 2019

Macro Reaction Engineering

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A first intense investigation in the kinetics of radical polymerization of NVP was done by Senogles et. al. [7] They revealed a variation of the activation energy for the propagation step Radical PolymerizationAn improved kinetic model for the radical polymerization of N-vinyl-pyrrolidone (NVP) in aqueous medium is developed. Quantum chemical simulations reveal that the transfer to polymer is of minor importance whereas the transfer to monomer by hydrogen abstraction in 3-position of the pyrrolidone ring leads to a radical with a double bond which initiates a new chain bearing a terminal double bond (TDB). The resulting dead chains with one, two, or more TDB are the main source for a strong increase of molar mass in batch reactors at high conversion due to long chain branching and crosslinking. This can be a source for gel formation and fouling in continuous reactors. www.advancedsciencenews.com www.mre-journal.de

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“…4 Moreover, an almost linear relationship is observed between the logarithm of the chain transfer constant ratio and the percentage of grafting (Fig. 4 Moreover, an almost linear relationship is observed between the logarithm of the chain transfer constant ratio and the percentage of grafting (Fig.…”

Section: Chain Transfer Constant Of the Polymeric Thiol Groupsmentioning

confidence: 90%

Grafting of styrene onto carbon fibers having pendant thiol groups

Fujisawa

Yosomiya

1982

Makromol. Chem.

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Carbon fibers containing thiol groups were produced by reacting carbon fiber oxidized by nitric acid, with excess thiirane. Then, graft polymerization with styrene was carried out in a sealed tube under nitrogen. The following order of initiating ability of the investigated initiators was found: di-tert-butyl peroxide > p-cumenyl hydroperoxide (CHPO) > dodecyl peroxide > benzoyl peroxide > 2,2'-azoisobutyronitrile. When CHPO was used as initiator, the rate of graft polymerization was maximum at [CHPO] = 0,Ol mol/l. Chain transfer constant and grafting efficiency, both calculated from the equations of Fox and others, were compared with the experimental results.0025-1 16X/82/12 2923-1

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Crosslinking in Monovinyl Monomers (I). By Chain Transfer With the Polymer Chain

Cited by 43 publications

References 11 publications

Branching in free radical polymerization due to chain transfer. Application to poly(vinyl acetate)

Branching in free radical polymerization due to chain transfer. Application to poly(vinyl acetate)

Side Reactions in Aqueous Phase Polymerization of N‐Vinyl‐Pyrrolidone as Possible Source for Fouling

Grafting of styrene onto carbon fibers having pendant thiol groups

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