Effects of esters, aldehydes and some impurities on the polymerization of vinyl acetate

Abstract

Effects of aliphatic esters, aldehydes and some impurities, as monovinyl and divinyl acetylene which exist normally in vinyl acetate, on the polymerization of vinyl acetate were studied. Esters and saturated aldehydes such as methyl acetate, ethyl acetate, isopropyl acetate and dimethyl oxalate etc., and acetaldehyde and butyraldehyde act only as transfer agent and the values of the transfer constants on these substances were determined. Unsaturated aldehyde such as crotonaldehyde and also benzaldehyde, and monovinyl and divinyl acetylene act as retarder. The several reaction constants relating the retarding effect were obtained. ZUSAMMENFASSUNG:Es wurde der EinfluB von aliphatischen Estern, Aldehyden und Verunreinigungen, die imvinylacetat iiblicherweise vorhanden sindwie Monovinylacetylen und Divinylacetylen a d die Polymerisation von Vinylacetat untersucht. Ester und gesattigte aliphatische Aldehyde, wie z. B. Methylacetat, Athylacetat, Isopropylacetat, Dimethyloxalat usw., Acetaldehyd und Butyraldehyd, wirken nur als ubertrager. Ihre tfbertragungskonstanten wurden bestimmt. Ungesattigte Aldehyde, wie Crotonaldehyd, aber auch Benzaldehyd, ferner Mono-und Divinylacetylen wirken als Verzogerer. Die Polymerisationsgeschwindigkeit von Vinylacetat in Gegenwdrt solcher Verzogerer wurde nach der Gleichung von KICE analysicrt, und die verschiedenen Geschwindigkeitskonstanten wprden bestimmt. *) This report is a summarization of several of the author' papers which appear in the 1) I. SAKURADA and R. INOUE, Chem. High Polymers (Japan) 7 (1950) 211. Industrially pure vinyl acetate, made by the KURASAIKI RAYON COMPANY, was used in all tests. The monomer was washed with aqueous NaHSO, and water. It was then dried and rectified. The fraction boiling at 72.5"C. was partially polymerized, and the unpoly-5) A. J. BUSELLI, M. K. LINDEMANN, and C. E. BLADES, J. Polymer Sci. 28 (1958) 485. 6) T. OHSUGI, Chem. High Polymers [Japan] 6 (1949) 460. 7) 0. L. WHEELER, S. L. ERNST, and R. N. CROZIER, J. Polymer Sci. 8 (1952) 409. 8 ) 0. L. WHEELER, E. LAVIN, and R. N. CROZIER, J. Polymer Sci. 9 (1952) 157. 9) M. YANO and M. MATSUMOTO, J. chem. SOC. Japan; Ind. Chem. Sect. (Kogyo Kagaku

Poly(vinyl ester) Block Copolymers Synthesized by Reversible Addition−Fragmentation Chain Transfer Polymerizations

“…49 This inherent impurity necessitates stringent monomer purification by fractional distillation or reactive purifications in order to achieve predictable vinyl ester polymerization results. 48,49 The level of impurities present in the vinyl ester feedstocks employed in the present work were below the limits of detection of gas chromatography and other available analytical methods.…”

“…The known batchwise variability of the inhibition periods associated with conventional free radical vinyl acetate polymerizations 8 in the absence of exogenously added inhibitors suggests that vinyl ester feed streams are inherently contaminated with impurities that quench free radical polymerizations. 48 This is not surprising in view of the hydrolytic instability of these monomers that produces a carboxylic acid and acetaldehyde, the latter of which is known to be a potent chain transfer agent in these polymerizations. 49 This inherent impurity necessitates stringent monomer purification by fractional distillation or reactive purifications in order to achieve predictable vinyl ester polymerization results.…”

“…In previous reports of vinyl ester RAFT homopolymerizations, monomers were purified by passage through basic alumina to remove hydroquinone that was added as a free radical polymerization inhibitor. The known batchwise variability of the inhibition periods associated with conventional free radical vinyl acetate polymerizations in the absence of exogenously added inhibitors suggests that vinyl ester feed streams are inherently contaminated with impurities that quench free radical polymerizations . This is not surprising in view of the hydrolytic instability of these monomers that produces a carboxylic acid and acetaldehyde, the latter of which is known to be a potent chain transfer agent in these polymerizations .…”

Effect of solvent on the microstructure of polyvinyl alcohol

“…This was because hydrogen activity on methanol molecule was stronger than the alfa-hydrogen on methyl acetate, which is consistent with the theoretical results. [17] 1…”

“…Therefore, in methanol solvent, the probability of chain transfer reaction on the polymer is higher; b. Methyl acetate is a good solvent for polyvinyl acetate, [17] which is conducive to the stretched state of the polymer and inhibits the intramolecular chain transfer reaction. Therefore, the degree of branching of PVA in methanol solvent is higher, which further produces a wider molecular weight distribution.…”