Branched Structure of Polyvinyl Acetate

Imoto, Saburo; Ukida, Junji; Kominami, Tsugio

doi:10.1295/koron1944.14.101

“…16 Murahashi, et al, have found that long branching on PV A does not affect the PV A-iodine reaction. 17 This result is reasonable, for the presence of long branching probably shows little effect with respect to the microstructure of PV A because of the small number of branching points per polymer molecule.…”

Section: Discussionmentioning

confidence: 99%

Iodine Reaction of Poly(vinyl alcohol) Fractionated by Foaming

Kikukawa

¹

,

Nozakura

²

,

Murahashi

³

1972

Polym J

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ABSTRACT:It has been confirmed that foam fractionation of an aqueous poly(viny1 alcohol)(PVA) solution produced PVAs with different reactivity in the PVA-iodine reaction, namely the color intensity decreased with increase in the fraction number. This result was found not only with a PVA derived from poly(vinyl acetate)(PVAc), but also with a specimen derived from cationically polymerized poly(vinyl trimethylsilyl ether)(poly(VOSi)). Particularly in the case of PVA obtained from PVAc (DP, 1652, and syndiotacticity, 50.0% in dyad), the variation of color intensity among the fractions cannot be explained by any one of the structural factors such as molecular weight, the 1,2-glycol structure, stereoregularity, and the carbonyl group in the main chain. Therefore another molecular structure, for example short branching, which will affect the PV A-iodine reaction and the foam fractionation, should be considered. The result also indicates the homogeneity of PV A from PV Ac with respect to stereoregularity and the 1,2-glycol structure contents. In the case of PVA obtained from poly(VOSi)(DP, 1496, and syndiotacticity, 37 .5% in dyad), the fractionation with respect to stereoregularity has occurred; syndiotacticity of PVA contained in foam layers was higher than that in the residual solution. This result indicates that the PVA derived from poly(VOSi) consisted of stereoblock and/or a mixture of PVA of different tacticity.KEY WORDS Poly(vinyl alcohol) / Foam Fractionation / Fractionation / PVA-Iodine Reaction / Stereoregularity / 1,2-Glycol Structure / Branching / Iodine / Imai, et al., separated a poly(vinyl alcohol) (PV A) derived from radically polymerized poly (vinyl acetate) (PV Ac) into fractions by foaming an aqueous solution. 1 The fractions showed different reactivity in the PV A-iodine reaction though there was little difference in degree of polymerization and in the 1,2-glycol content. They suggested that PV A was fractionated according to stereo regularity. But there arises a question in considering the presence of a wide difference of stereoregularity among individual polymer molecules of a radical polymer. method of determination of stereoregularity was established, 2 PV A samples with different stereoregularities have been prepared in order to study the effect of stereoregularity on properties of PV A. 3 The increase of isotacticity of PV A lowers melting point, crystallinity, and color intensity of the PVA-iodine reaction. 3 -5 The increase of the 1,2-glycol structure also deteriorates the crystallinity 4 and fades the color of the PV Aiodine reaction. 5 In addition, Shibatani, et al., have shown that a minor change in 1,2-glycol contents remarkably affects the PV A___:iodine color reaction. 6 It is known that even a minor change in molecular structure of PV A influences the properties of PVA. Factors, which may affect crystallinity and the PVA-iodine reaction, involve the 1,2-glycal structure, the carbonyl group in the main chain, branching, and stereoregularity. Since the * Present address: Department...

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“…Investigation has shown that chain transfer to polymer occurs predominantly on the acetate methyl group in preference to the chain backbone; one estimate of the magnitude of the predominance is 40-fold (94,95). The number of branches per molecule of poly(vinyl acetate) polymerized at 60 • C is ca 3, at 80% conversion.…”

Section: Chain Transfermentioning

confidence: 99%

Vinyl Acetate Polymers

Cordeiro¹,

Petrocelli²

2005

Kirk-Othmer Encyclopedia of Chemical Technology

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This article provides information related to the chemistry, manufacture, and use of poly(vinyl acetate). Summary information is provided on vinyl acetate as the primary ingredient in the manufacture of the polymer. This information focuses on the chemical and physical properties of the material and the handling and safety aspects pertinent to its use in a polymerization system. The key material properties of poly(vinyl acetate) homopolymer and copolymers are described. The influences of key components of the polymerization recipe are discussed, such as the effect of the stabilizers, comonomers, and chain‐transfer agents on the reaction and product. Polymerization process aspects are covered with a focus on emulsion polymerization. The mechanisms involved in the vinyl acetate polymerization reaction are discussed. An overview is provided of the applications of the homopolymer and copolymers in adhesives, paint, paper, and other areas. General information is provided in these areas with references which can be used to obtain more specific information.

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Vinyl Acetate Polymers

Cordeiro¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

1

0

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This article provides information related to the chemistry, manufacture, and use of poly(vinyl acetate). Summary information is provided on vinyl acetate as the primary ingredient in the manufacture of the polymer. This information focuses on the chemical and physical properties of the material and the handling and safety aspects pertinent to its use in a polymerization system. The key material properties of poly(vinyl acetate) homopolymer and copolymers are described. The influences of key components of the polymerization recipe are discussed, such as the effect of the stabilizers, comonomers, and chain‐transfer agents on the reaction and product. Polymerization process aspects are covered with a focus on emulsion polymerization. The mechanisms involved in the vinyl acetate polymerization reaction are discussed. An overview is provided of the applications of the homopolymer and copolymers in adhesives, paint, paper, and other areas. General information is provided in these areas with references which can be used to obtain more specific information.

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Branched Structure of Polyvinyl Acetate

Cited by 25 publications

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Iodine Reaction of Poly(vinyl alcohol) Fractionated by Foaming

Iodine Reaction of Poly(vinyl alcohol) Fractionated by Foaming

Vinyl Acetate Polymers

Vinyl Acetate Polymers

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