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TAPPI T 203 Alpha Beta Gamma cellulose

Standard:

TAPPI

Method:

TAPPI T 203

Title:

Alpha-, beta- and gamma-cellulose in pulp

Scope

The TAPPI T 203 method for determination of alpha-, beta- and gamma-cellulose can be applied to bleached or delignified pulps only. Unbleached and semi-bleached pulps must be delignified before testing.

Summary

Pulp is extracted consecutively with 17.5% and 9.45% sodium hydroxide solutions at 25°C. The soluble fraction, consisting of beta- and gamma-celluloses, is determined volumetrically by oxidation with potassium dichromate, and the alpha-cellulose, as an insoluble fraction, is derived by difference.

Significance

Separation of the cellulose in pulp into alpha-, beta- and gamma-cellulose fractions is an empirical procedure, originally devised by Cross and Bevan around 1900, and has been widely used to evaluate pulps for various purposes, such as aging characteristics and response to refining operations. In a modified form, the method was adopted first as a TAPPI tentative standard in 1931.

In general, the alpha-cellulose indicates undegraded, higher-molecular-weight cellulose content in pulp; the beta-cellulose indicates that of a degraded cellulose, and the gamma-cellulose consists mainly of hemicellulose.

Samples

Clients can order alpha-cellulose only analysis for a slightly lower fee.

 

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