Optimization of solution fractionation of poly(vinyl acetate)

Klein, Joachim; Werner, Michael

doi:10.1002/macp.1978.021790413

Cited by 3 publications

(2 citation statements)

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“…The literature has shown several techniques that allow the separation of PS fractions. To highlight is a study by Klein and Werner . The authors argue that polymer fractionation techniques based on solubility equilibrium, which can be employed as precipitation or solution fractionation, remain an important method of polymer characterization and offer the possibility to produce polymer samples with narrow molecular weight distribution in a preparative dimension.…”

Section: Resultsmentioning

confidence: 99%

“…The authors argue that polymer fractionation techniques based on solubility equilibrium, which can be employed as precipitation or solution fractionation, remain an important method of polymer characterization and offer the possibility to produce polymer samples with narrow molecular weight distribution in a preparative dimension. Meanwhile, the method of GPC, which is most commonly used as an analytical tool today, has limitations in preparative scale, particularly if the analysis of chemical composition and molecular size is required . As such, CAMDIH can be considered an excellent alternative for two reasons.…”

Section: Resultsmentioning

confidence: 99%

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A new thermoset for separation of polystyrene and naphthalene in preparative chromatography

Rosa

Botaro

2017

J of Applied Polymer Sci

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Many research groups in recent years have demonstrated the importance of obtaining new materials and reducing environmental impact. In this context, the chemical modification of cellulose and its derivatives has received much attention. This study synthesized cellulose acetate gel (CAMDIH) obtained through the modification of cellulose acetate (CA) with a degree of substitution of 2.5, by crosslinking reactions using 4,4 0 -diphenylmethane diisocyanate in homogeneous medium. The formation of crosslinks were observed by the presence of Fourier transform infrared spectroscopy absorption bands at 3046 and 864 cm 21 , which correspond to the absorption of aromatic groups associated with the incorporation of 4,4 0 -diphenylmethane diisocyanate in the CA structure. The potential applications of the gel as a stationary phase were tested using column chromatography in the fractionation and separation of standard solutions of polystyrene and naphthalene. The findings showed the effectiveness of the gel as a stationary state in the separation of mixture compounds. Furthermore, the study found that CAMDHI is an innovative material when considering its simple synthesis and the low costs involved in the process.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A new thermoset for separation of polystyrene and naphthalene in preparative chromatography

Rosa

Botaro

2017

J of Applied Polymer Sci

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Optimization of solution fractionation of poly(vinyl chloride)

Klein

Schriever

1978

Makromol. Chem.

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The optimization of solution fractionation of poly(viny1 chloride) (PVC) is described with regard to the variation of several parameters. The best separation efficiency is obtained by a single-step discontinuous solution fractionation at the following conditions: solvent: cyclohexanone (CHN); nonsolvent: ethylene glycol (EG); temperature: 130"C, isothermal; contact-time: 2 h per fraction; amount of polymer: 2 mg/g support (glass beads). An essential improvement with respect to the separation of high molecular weight species can be achieved, applying a re-deposition method of the polymer remaining in the column after half of the fractionation steps. This diminishes the unfavorable formation of a molecular weight-and concentration gradient along the column, occurring during fractionation. The optimally controlled single-stage discontinuous solution fractionation of PVC turns out to be superior to multistage processes. This is attributed to the very critical problem of formation of insoluble microcrystalline aggregates with increasing duration of stay of the polymer in the column. The efficiency of the fractionation technique can be established by the characterization of fractions (center fractions: R,/M, < 1,l) and by confirmation of small differences in molecular weight distributions, shown by other methods. ' )Auszug aus der Dissertation von Eckhard Schriever: ,,Optimierung der Losefraktionierung von Polyvinylchlorid", TU Braunschweig 1977.

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Efficiency of polymer fractionation—A review

Mencer

1988

Polymer Engineering & Sci

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With respect to molecular masses, polymers are polydispersive. Since many of their properties depend on the distribution of molecular masses, to study this correlation it is necessary to have samples of narrow molecular mass distribution or samples with accurately defined distribution. In spite of the developmental progress of fast instrumental methods (analytical and preparative gel chromatography) used to determine the molecular mass distribution curve and to obtain higher amounts of fractions of narrow molecular mass distributions, there still exists an interest in classical methods of fractionation. On the basis of a survey of monographs on polymer fractionation, numerous publications and personal experience, this review describes primarily what is an efficient fractionation. Afterwards, factors that affect fractionation efficiency according to the type of effects arc given and causes of their action are described. Conditions under which efficient fractional precipitation and fractional solution methods are applied are considered separately. At the end of the review, criteria on the basis of which fractionation efficiency is evaluated are considered in detail.

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Optimization of solution fractionation of poly(vinyl acetate)

Cited by 3 publications

References 8 publications

A new thermoset for separation of polystyrene and naphthalene in preparative chromatography

A new thermoset for separation of polystyrene and naphthalene in preparative chromatography

Optimization of solution fractionation of poly(vinyl chloride)

Efficiency of polymer fractionation—A review

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