Electrokinetic Potential on Cellulose

Kanamaru, Kisou

doi:10.2115/fiber1925.7.29

Cited by 2 publications

(3 citation statements)

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“…From the plots of the conversion versus time curves obtained at 0.48 M initial monomer concentration shown in Figures 19 and 20, the plot of the conversion versus molecular weight curve obtained at 0.48 M initial monomer concentration shown in Figure 23 and the log–log plot of M w versus initial monomer concentration shown in Figure 24, three phenomena were observed: (1) a rapid increase in the molecular weight at low monomer % conversion followed by a slight increase in molecular weight during the “constant‐rate” period (interval II), (2) a slight gel effect between 66–70.5% conversion and polymer degradation after 70.5% conversion in the case of an emulsion containing 0.48 M initial monomer concentration, and (3) the weight average molecular weight increased with increasing initial monomer concentration (i.e., M w α[Monomer] 0.18 ), to a point, then became independent of initial monomer concentration. The gel effect phenomenon was observed by Zimmt,49 Trommsdorff and colleagues,63 and Kanamaru and Terasoki64 in their works on the emulsion polymerization of MMA. It was attributed to the reduction in termination rates as the viscosity of the medium increased at higher % conversion.…”

Section: Resultsmentioning

confidence: 76%

“…Trommsdorff and colleagues63 studied the emulsion polymerization by using turkey red oil as the surfactant and potassium persulfate as the initiator, and found that the polymerization rate was not influenced significantly by variation of the surfactant concentration in the range of 0.125–4%. Kanamara and Terasoki64 studied the emulsion polymerization of MMA at 70°C by using sodium lauryl sulfate as the surfactant and ammonium persulfate as the initiator. They found that the values of degree of polymerization (DP) varied, not to the −0.6 power of the initiator concentration predicted by the Smith–Ewart Case II Kinetics, but to the −0.46 to −0.3 power.…”

Section: Resultsmentioning

confidence: 99%

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Ultrasonically initiated free radical-catalyzed emulsion polymerization of methyl methacrylate (i)

Chou

Stoffer

1999

J. Appl. Polym. Sci.

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SYNOPSIS:The emulsion polymerization of methyl methacrylate initiated by ultrasound has been studied at ambient temperature using sodium lauryl sulfate as the surfactant. The investigation includes the: (1) nature and source of the free radical for the initiation process; (2) effects of different types of cavitation; and (3) dependence of the polymerization rate, polymer particle number generated, and the polymer molecular weight on acoustic intensity, argon gas flow rate, surfactant concentration, and initial monomer concentration. It was found that the polymerization could be initiated by ultrasound in the emulsion systems containing methyl methacrylate, water, and sodium lauryl sulfate at ambient temperature in the absence of a conventional initiator. The source of the free radical for the initiation process was found to come from the degradation of the sodium lauryl sulfate, presumably in the aqueous phase. The weight average molecular weight of the poly(methyl methacrylate) obtained varied from 2,500,000 to 3,500,000 g mol Ϫ1, and the conversion for polymerization was up to 70%. Deviations from the Smith-Ewart kinetics were observed. The polymerization rate was found to be proportional to the acoustic intensity to the 0.98 power; to the argon gas flow rate to the 0.086 power; to the surfactant concentration to the 0.08 power, with the 0.035M-0.139M surfactant concentration range; and to the surfactant concentration to the 0.58 power, with the 0.139M-0.243M surfactant concentration range. The polymerization rate was found to increase with increasing initial monomer concentration up to a point where it became independent of initial monomer concentration. The polymer particle number generated per milliliter of water was found to be proportional to the acoustic intensity to the 1.23 power; to the argon gas flow rate to the 0.16 power; to the surfactant concentration to the 0.3 power, with the 0.035M-0.139M surfactant concentration range; and to the surfactant concentration to the 1.87 power, with the 0.139M-0.243M surfactant concentration range. The polymer weight average molecular weight was found to be proportional to the acoustic intensity to the 0.21 power, and to the argon gas flow rate to the 0.02 power. It was found to be inversely proportional to the surfactant concentration to the 0.12 and 0.34 power, with the 0.035M-0.139M and the 0.139M-0.243M surfactant concentration ranges, respectively. The polymer yield and polymerization rate were found to be much larger than those obtained from an ultrasonically initiated bulk polymerization method. The polymerization rates obtained at ambient temperature were found to be similar to or higher than those obtained from the conventional higher temperature thermal emulsion polymerization method. This investigation demonstrated the capability of ultrasound to both initiate and accelerate polymerization in the emulsion system, and to do this at a lower temperature that could offer substantial energy savings.

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Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Ultrasonically initiated free radical-catalyzed emulsion polymerization of methyl methacrylate (i)

Chou

Stoffer

1999

J. Appl. Polym. Sci.

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“…A summation of such tests has been compiled by Heermann [42] and by Tatu [104]. If we omit such tests as solubility in calcium thiocyanate [68], heats of combustion [ 11 ] , refractivity [64], electrokinetic properties [65,91], Nessler's reagent [24,26,38], specialized dying tests [29,32,39,40,62,75,82,99] , ferricyanide test [28], or microscopic examination [33,41,94] which are of recent introduction (and hence incompletely evaluated or designed for special industrial control) it is evident that the bulk of the alleged &dquo;knowledge&dquo; of the structure of oxidized celluloses rests on the results of methylene-blue absorption, cuprammonium hydroxide viscosity (fluidity), and copper number determinations. The interpretation of these tests was evolved from an examination of oxidized celluloses of variable and unknown chemical structures; then the results of such tests were applied to determining the structure of oxidized celluloses !…”

Section: C0evolutionmentioning

confidence: 99%

The Formation and Properties of Oxidized Celluloses

Unruh¹,

Kenyon²

1946

Textile Research Journal

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A consideration of several aspects of past research in oxidized cellulose leads to the following summary of the present status of our knowledge of its structure.(a,) Much of the published data relates to heterogeneous products and hence is of little utility in determining chemical structure. (b) Two types of &dquo;oxidized cellulose&dquo; of reasonable chemical and physical homogeneity have been prepared by oxidation of the 2,3-hydroxyls and the primary (6) hydroxyl groups of the anhydro-glucose units of cellulose. (c) These are not truly &dquo;oxidized celluloses&dquo; but new polymers in their own right, with chemical properties distinct from those of cellulose. They should be considered and named as specific chemical entities.(d) Further advance in our knowledge of oxidized cellulose structure and behavior must rest on examination of physically homogeneous products resulting from the application of oxidants which attack specific points of the cellulose structure.(e) Structural elucidation must employ determinations of unambiguous organic groups under controlled conditions.( f ) Only a few methods of structural determinations have been employed to date that can be accepted with some assurance. These are:( 1 ) Estimation of aldehyde groups by reaction with hydroxylamine. The aldehyde endgroup determination by alkaline iodine solutions is satisfactory for the purpose intended but of unproved merit for alkalisensitive oxidized celluloses.(2) Determination of combined uronic acid groups by evolution of carbon dioxide. (3) Determination of total carboxyl groups (including those of uronic acid) by the calcium acetate technique. (4) Determination of residual hydroxyl groups by acetylation or nitration. (5) Degradation of the oxidized celluloses by known reactions and identification of the fission products. (g) Owing to alkali-sensitivity of the oxidized celluloses, the cuprammonium hydroxide and copper number values are unreliable for such materials.

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Electrokinetic Potential on Cellulose

Cited by 2 publications

References 0 publications

Ultrasonically initiated free radical-catalyzed emulsion polymerization of methyl methacrylate (i)

Ultrasonically initiated free radical-catalyzed emulsion polymerization of methyl methacrylate (i)

The Formation and Properties of Oxidized Celluloses

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