Semicontinuous emulsion polymerization of vinyl acetate IX. Decomposition of the initiator

Abstract

The way in which the decomposition reaction of a persulfate initiator is influenced by the nature of reactants of the polymerization medium and by the working conditions during the semicontinuous polymerization and copolymerization of vinyl acetate is studied. The rate of the splitting reaction of potassium persulfate is higher in the aqueous phase containing a protective colloid and surfactant. The splitting rate is smaller in the presence of vinyl acetate. The presence of hydrophobic comonomers decreases the rate ofinitiator decomposition. An increase of the addition rate of monomers leads to an increase of the obtained polymer and of the splitting rate of the initiator. Semikontinuierliche Emulsionspolymerisation von Vin.dacetat. IX. Zer.~etziingsreuktion rles InitiatorsDer EinfluD der Reaktanten im Polymerisationsmedium und der Reaktionsbedingungen auf die Zersetzungsreaktion eines Persulfatinitiators wird untersucht. Die Geschwindigkeit der Spaltungsreaktion von Kaliumpersulfat steigt bei Anwesenheit eines Schutzkolloids und einer oberflkhenaktiven Substanz in der wPDrigen Phase. in Gegenwart von Vinylacetnt ist die Spaltungsgeschwindigkeit niedriger. Bei Anwesenheit hydrophober Comonomere nimmt die Zersetzungsgeschwindigkeit dcs Initiators ab. Ein Anstieg der Zufiihrungsgeschwindigkeit der Monomere erhoht die Menge an erhaltenem Polymer und die Spaltungsgeschwindigkeit des Initiators. DONESCU and FUSULAS: Scmicontinuous emulsion polymerizntion of vinyl acetate. 1X Systcm')Acta Polymcriu 42 (1Wl) Nr. 10

Microemulsions of a Vinyl Acetate/2-Ethylhexyl Acrylate Monomer Mixture

“…The formation of microemulsions is based on the very pronounced decrease of the interfacial tensions between organic and aqueous phases . In the case of a PrOH/H 2 O mixture the air/liquid interfacial tension decreases with increasing alcohol concentration and, above a certain concentration, it is no longer modified by the presence or nature of the surfactant . Therefore in “surfactant-free” systems one can obtain microemulsions only above the high PrOH concentration range (Figures a and a) while in the presence of the surfactant they may be formed over concentration ranges rich in aqueous phase (Figures b and b).…”

“…Studies carried out on VAc microemulsions have shown that their composition range depends on the nature of the hydrocarbonate moiety of the SCC. , The presence of a more hydrophobic comonomer, for example, 2-ethylhexyl maleate (DEHM), diminishes the probability of microemulsion formation. , …”

“…The possibility to form microemulsions of vinylic and acrylic monomers in the presence of short chain cosurfactants (SCCs) has recently been extensively studied. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Microemulsions of o/w, bicontinuous, or w/o structure can be formed to an extent controlled by the o/w phase ratio. [2][3][4][5][6][7][8] The existence of monomer microemulsions even in systems without surfactant 2,3 confirms some previously published results 18 regarding "detergentless microemulsions".…”

“…Methyl methacrylate (MMA), [1][2][3][4][5][6][7][8] styrene, 9 vinyltoluene, 10 and vinyl acetate [11][12][13][14][15][16] (VAc) microemulsions exist because the systems containing SCC and water can be nanostructured. [19][20][21] The short (C 1 -C 3 ) hydrocarbonate chains of the SCC may induce hydrophobic demixing.…”

High pressure semibatch emulsion and miniemulsion copolymerization of vinyl acetate and ethylene

“…The successful incorporation of other highly water‐insoluble monomers via miniemulsion polymerization has been demonstrated 24 . Although the conventional emulsion process of VAE has been studied and even practiced commercially, 25,26 little has been reported on the miniemulsion copolymerization of VAc and gaseous ethylene. Recently, Guo et al 16 reported that gaseous monomer with very low water solubility such as ethylene can be effectively incorporated into a copolymer phase in miniemulsion copolymerization of VAc and ethylene with ethylene partial pressure of 66.7 psig (460 kPa).…”