Viskosit�tszahl-Molekulargewichts-Beziehung f�r Cellulose und Untersuchungen von Nitrocellulose in verschiedenen L�sungsmitteln

Immergut, E. H.; Schurz, J.; Mark, H.

doi:10.1007/bf00899186

Cited by 44 publications

(17 citation statements)

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“…Samples were air-dried overnight prior to viscosity measurements in 0.5 M CED (copper (II) ethylenediamine) according to SCAN-C 15:62. The degree of polymerisation was calculated according to Immergut et al (1953), see Eq. 1.…”

Section: Degree Of Polymerization (Dp) Of Cellulosementioning

confidence: 99%

Dissolution of wood components during hot water extraction of birch

2021

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Autohydrolysis-based pretreatments enable extraction of hemicellulose from wood tissue prior to the paper pulp cooking processes enabling their further use as platform chemicals and in material applications. In this study, hot water extraction of birch meal was conducted in a small flow-through system. The combination of high surface area of the milled material with increased driving force induced by constant flow of freshwater, together with fast evacuation of extract, enabled a detailed study of the dissolution process. Based on the findings, deeper insight into acidification and autohydrolysis progress was obtained.

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Section: Degree Of Polymerization (Dp) Of Cellulosementioning

confidence: 99%

Dissolution of wood components during hot water extraction of birch

2021

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“…It is worth noting that osmometry was originally used to determine the relationship between intrinsic viscosity and molecular weight [53]. It has been shown that under mild conditions, the degradation during cellulose nitration is negligible.…”

Section: How To Measure Molecular Weightsmentioning

confidence: 99%

Overview of Methods for the Direct Molar Mass Determination of Cellulose

2015

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Abstract:The purpose of this article is to provide the reader with an overview of the methods used to determine the molecular weights of cellulose. Methods that employ direct dissolution of the cellulose polymer are described; hence methods for investigating the molecular weight of cellulose in derivatized states, such as ethers or esters, only form a minor part of this review. Many of the methods described are primarily of historical interest since they have no use in modern cellulose chemistry. However, older methods, such as osmometry or ultracentrifuge experiments, were the first analytical methods used in polymer chemistry and continue to serve as sources of fundamental information (such as the cellulose structure in solution). The first part of the paper reviews methods, either absolute or relative, for the estimation of average molecular weights. Regardless of an absolute or relative approach, the outcome is a molecular weight average (MWA). In the final section, coupling methods are described. The primary benefit of performing a pre-separation step on the molecules is the discovery of the molecular weight distribution (MWD). Here, size exclusion chromatography (SEC) is unquestionably the most powerful and most commonly-applied method in modern laboratories and industrial settings.

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“…Intrinsic viscosities of ethanol-acid treated samples were measured according to standard ISO/ FDIS 5351:2009 and average degrees of polymerization were calculated from intrinsic viscosity values (Immergut et al 1953) to observe changes in cellulose chain length as a function of treatment time and temperature. One untreated sample and one treated for 5 h at 65°C in ethanol without hydrochloric acid were used as references.…”

Section: Degree Of Polymerization Of Cellulosementioning

confidence: 99%

Enhancement of cellulose dissolution in water-based solvent via ethanol–hydrochloric acid pretreatment

Trygg

Fardim

2011

Cellulose

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Cellulose dissolution in water-based solvents is essential for processing of regenerated cellulose products such as fibres, films and particles. Cellulose dissolution in NaOH-urea aqueous solution has emerged as a simple and attractive alternative for processing cellulose solutions. However, this solvent requires energy intensive pretreatments such as milling or refining. In this paper we investigate a one step chemical pretreatment method using ethanol-hydrochloric acid prior to the dissolution of cellulose in NaOH-urea-water. The dissolution mechanism of the pretreated sample was initially examined in diluted cupri-ethylenediamine and 7% NaOH-12% urea-water solvent using optical microscopy methods and field emission scanning electron microscopy. The apparent energy of activation for the viscous flow of ethanol-acid pretreated pulp in NaOH-urea-water was calculated using rheological methods. Our results showed that the dissolution of pretreated pulp was achieved up to 4% cellulose concentration. We suggest that the enhancement of dissolution was due to a combination of degradation of remnant primary fibre wall layer and reduction of degree of polymerization of cellulose.

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Viskosit�tszahl-Molekulargewichts-Beziehung f�r Cellulose und Untersuchungen von Nitrocellulose in verschiedenen L�sungsmitteln

Cited by 44 publications

References 0 publications

Dissolution of wood components during hot water extraction of birch

Dissolution of wood components during hot water extraction of birch

Overview of Methods for the Direct Molar Mass Determination of Cellulose

Enhancement of cellulose dissolution in water-based solvent via ethanol–hydrochloric acid pretreatment

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