Randomly Branched Polymers. II. Computer Analysis of Gel-Permeation Chromatogram

Kurata, Michio; Okamoto, Hiroyoshi; Iwama, Masamichi; Abe, Mitsuo; Homma, Takeshi

doi:10.1295/polymj.3.739

Cited by 33 publications

(11 citation statements)

References 13 publications

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“…3 The molecular weight distribution and number-average molecular weight of the polymers were determined from the results of the measurement of intrinsic viscosity and GPC by the method of Kurata et al 5 Results of the polymer analyses are shown in Table 11.…”

Section: Characterization Of Polymersmentioning

confidence: 99%

Oxidation behavior of isoprene polymers and butadiene polymers

Sato

Sakota

Egami

et al. 1977

J. Appl. Polym. Sci.

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SynopsisThe oxidation behavior of cis-1,4-polyisoprene, emulsion polyisoprene, emulsion isoprenehtyrene copolymers, and emulsion butadienehtyrene copolymers by heat aging or ultraviolet irradiation has been investigated from the change of gel fraction and molecular weight distribution. It was determined that the oxidation behavior of both isoprene and butadiene polymers is strongly dependent on the composition of the polymers as well as on the microstructure of the polymers. In the case of oxidation by heat aging, the probability ratio of chain scission to crosslinking of both isoprene and butadiene copolymers increases gradually with increasing styrene fraction. In the case of oxidation by ultraviolet irradiation, isoprene copolymers show a remarkable increase in the probability ratio of chain scission to crosslinking, whereas butadiene copolymers show substantially no change with increase in styrene fraction. It was also demonstrated that both isoprene and butadiene polymers show a greater tendency for crosslinking with oxidation by ultraviolet irradiation than with oxidation by heat aging.

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Section: Characterization Of Polymersmentioning

confidence: 99%

Oxidation behavior of isoprene polymers and butadiene polymers

Sato

Sakota

Egami

et al. 1977

J. Appl. Polym. Sci.

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“…Considering the error in A3 originating from the 3-% error in the estimate of the intrinsic viscosity, the lower limit of the estimate of A3 might be 10- 6 in the present analysis. The observed value of A3 for the sample H-1 polymerized to the conversion of 79.2% at 90°C was 1.6 x 10- 5 and Mw was found to be 3.44 X 10 5 • Therefor, this polymer has 5.5 weight-average long-chain branches per polymer chain. The observed value of A3 for H-2 was lower than that for H-1, though H-2 was polymerized to a higher conversion than H-1.…”

Section: Gpc Measurementmentioning

confidence: 87%

“…Kurata, et al, 5 -7 also reported the same method independently, and discussed the limit of reliability by showing an example of the application to branched polystyrene. In the present paper, the amount of long-chain branches in PV A was determined by means of Kurata's method, [5][6][7] and the results were compared with those expected * Leave of absence from Department of Polymer Science, Kyungpook National University, Korea.…”

mentioning

confidence: 99%

Long Branching in Poly(vinyl acetate) and Poly(vinyl alcohol). V. Determination of the Long-Chain Branching in Poly(vinyl alcohol).

Morishima

Kim

Nozakura

1976

Polym J

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ABSTRACT:Long branching in poly(vinyl alcohol) (PV A) was quantitatively determined from measurements of the intrinsic viscosity and gel-permeation chromatography of derived poly(vinyl acetate) (PVAc) according to Kurata's method. The average number of branch points per unit molecular weight, .Aa, was observed to lie in the range of 10-6-10-5 for PV A obtained from PV Ac polymerized at 60°C in bulk. The tendency for the values of .Aa to increase with the increase in the conversion of polymerization of the parent polymer was found to be in close agreement with that expected from the kinetic equation proposed in our previous paper.KEY WORDS Long Branching I Poly(vinyl alcohol) 1 Poly(vinyl acetate) I Gel-Permeation Chromatography I Intrinsic Viscosity I Branching Parameter 1In previous papers 1 ' 2 the formation of longchain branches in poly(vinyl alcohol) (PYA) was kinetically analyzed. It was clarified that the long branches in PV A are exclusively formed by the chain transfer to polymer and that the amount of the branch increases as the conversion increases and as the polymerization temperature rises. As a result, the amount of long branches in PV A derived from bulk polymerization of vinly acetate at 60°C is predictable from kinetic equations. However, the quantitative determination of long-chain branches for a given PV A specimen has not been reported so far. A method has been proposed for estimating the degree of branching from the elution curve of GPC and the intrinsic viscosity of unfractionated samples. Drott, et al., 3 ' 4 determined long branches in polyethylene using this method. Kurata, et al., 5 -7 also reported the same method independently, and discussed the limit of reliability by showing an example of the application to branched polystyrene. In the present paper, the amount of long-chain branches in PV A was determined by means of Kurata's method, 5-7 and the results were compared with those expected * Leave of absence from Department of Polymer Science, Kyungpook National University, Korea. 196 from the kinetic scheme proposed in our previous work. 2 EXPERIMENTAL MaterialsVinyl acetate was purified according to the previous paper. 2 Tri-n-butylborane was distilled under reduced pressure (bp, 90-91 oq9 mmHg), and 2,2' -azobisisobutyronitrile (AIBN) was recrystallized from methanol. Benzene was dried over CaC12 and distilled through a Widmer column twice. Methanol and tetrahydrofuran were distilled through a Widmer column. Polymerization of Vinyl AcetatePolymerization of vinyl acetate at ooc was carried out in the following way. To 21.9 g of vinyl acetate and 8.1 g of methanol contained in a 50-ml Shlenk tube kept at ooc were added 0.23 ml of tri-n-butylborane (0.5 mol% to monomer) and 1 ml of oxygen as initiators under an atmosphere of nitrogen. The polymerization was quenched at conversion lower than 10% by the addition of 1 ml of 5-% methanolic solution of hydroquinone. The contents were concentrated and poured into n-hexane to precipitate poly(vinyl acetate) (PVAc). The precipitated pol...

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“…The method is based on the MWD functions of St~ckmayer'~ and on the expressions for g [eqs. (9) and No viscosity measurements and no iterative procedure are necessary.…”

Section: Prediction Of Gpc Behavior Of Randomly Branched Polymersmentioning

confidence: 99%

Analysis of branched poly(ethylene terephthalate)

Weisskopf

1990

J of Applied Polymer Sci

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SynopsisPoly(ethylene terephthalate) modified with l,l,l-trishydroxymethyl propane (THP) and pentaerythritol was analyzed with respect to branching by combined GPC/viscometry measurements. The average effective functionality of the branching molecules was calculated and compared with the theoretically attainable functionality, thus permitting one to distinguish between different branching theories. Maximum effectiveness was achieved only at low concentrations of the modifiers added. Pentaerythritol and THP were found equivalent in the ratio 1 : 3, estimated from their influence on the polydispersities of the branched polyester. It was shown that apparent molecular weights obtained from GPC calibration with linear standards can be converted by correction factors. The resulting molecular weight averages of the branched PET samples were in a good agreement with those from the GPC/viscometry iteration procedure.

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Randomly Branched Polymers. II. Computer Analysis of Gel-Permeation Chromatogram

Cited by 33 publications

References 13 publications

Oxidation behavior of isoprene polymers and butadiene polymers

Oxidation behavior of isoprene polymers and butadiene polymers

Long Branching in Poly(vinyl acetate) and Poly(vinyl alcohol). V. Determination of the Long-Chain Branching in Poly(vinyl alcohol).

Analysis of branched poly(ethylene terephthalate)

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