Significato e uso

4.1 Questo test è una misura sensibile per la degradazione della cellulosa derivante dall'azione del calore, light, acids, basi, oxidants and reducing agents during processing or purification. If desired, the intrinsic viscosity value can be converted to degree of polymerization (DP) or intrinsic fluidity.

4.2 Cellulose solutions are not Newtonian liquids; That is, their viscosity depends on the shear rate or velocity gradient during the measurement. For low molecular weight (DP) samples and low concentration samples, this effect is smaller than for high DP samples and high concentration samples. For cellulose and concentrations contained within the limits described in this test method, the effect of shear rate is assumed to be negligible for judging purposes. This assumption may not be valid for other conditions and for research purposes, but a way to discuss this effect is beyond the scope of this test method.

Metodo di prova standard ASTM D1795-2013 per la viscosità caratteristica della cellulosa

Fare un passo 1: Scopo

1.1 This test method includes the determination of the intrinsic viscosity of purified cellulose, such as bleached wood pulp, cotton lint and regenerated cellulose. It is suitable for all cellulose samples with an intrinsic viscosity of 15dl/g or less. Most natural (unpurified) cellulose has intrinsic viscosity values that are too high to be measured by this test method.

Nota 1 – The use of cuprammonium hydroxide solution for conventional viscosity determination is described in Method T206m-55 of the Pulp and Paper Industry Technical Association on “Cuprammonium Dispersion Viscosity of Pulp” and Joint Army-Navy Specification JAN-C-. 206.

1.2 I valori espressi in unità SI sono considerati valori standard. Nessun'altra unità di misura è inclusa in questo standard.

1.3 Questo standard non è destinato ad affrontare tutti i problemi di sicurezza, se presente, legati al suo utilizzo. È responsabilità degli utenti di questo standard stabilire adeguate pratiche di sicurezza e salute e determinare l'applicabilità delle restrizioni normative prima dell'uso.