Viscosity measurement is a reasonable and useful routine characterization and quality control measurement for fibril cellulose production. The method is based on vane geometry, which is widely accepted as a convenient way of testing viscous, polydisperse materials. The method is particularly advantageous for testing samples that are significantly heterogeneous or that could slip when tested with conventional, smooth spindle geometries such as plate or coaxial cylinder. Viscosity describes a suspension's internal resistance to flow. The higher the fibrillation degree of the fibril cellulose, the more internal friction is formed. In fibrillated celluloses, the size, the aspect ratio and the amount of fibrils are known to affect the viscosity. The routine viscosity procedure includes specified rotational speeds of a spindle from 0.5rpm to 100rpm. The apparent yield stress can also be measured during the same measurement. The measuring is performed for a sample volume of 250ml at a controlled temperature of 20°C ± 1°C. The repeatability of the Brookfield method is fairly good and the method has been found to be suitable for charactetization of various types of fibril cellulose samples. Because of different nature of unmodified and chemically modified fibril cellulose samples, the method has been fine-tuned for these two sample categories. The viscosity measurement described here has been unified within several laboratories and the same measurement procedure is now in routine use for characterization and quality control of fibril cellulose. In the future, commensurable characterization methods are needed in order to compare results between different laboratories worldwide. Based on these experiences we endeavour to get this method for standardization.
|Title of host publication||International Conference on Nanotechnology 2013|
|ISBN (Print)||978-1 -5108-1568-1|
|Publication status||Published - 2013|
|MoE publication type||Not Eligible|
|Event||2013 Tappi International Conference on Nanotechnology for Renewable Materials - Stockholm, Sweden|
Duration: 24 Jun 2013 → 27 Jun 2013
|Conference||2013 Tappi International Conference on Nanotechnology for Renewable Materials|
|Period||24/06/13 → 27/06/13|
- fibril cellulose
Sneck, A., & Lahtinen, P. (2013). Viscosity measurement: A valuable tool for routine quality control of fibril cellulose. In International Conference on Nanotechnology 2013 (pp. 840-848). TAPPI Press.