University of Pretoria
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Rheology, turbidity and tensile data for nanocellulose and xanthan composites

posted on 2023-11-27, 09:35 authored by Zian HoekZian Hoek, Walter FockeWalter Focke

The rheology data is for nanocellulose fibres (CNF) with xanthan gum added. Samples containing 1 % CNF, never dried, with 0 %, 15 %, 25 %, and 50 % xanthan gum, relative to the mass CNF, was diluted by taking 50 mg of sample and adding 50 g of deionized water. Dried CNF/xanthan composites were then redispersed to similar concentrations by shear mixing for 3 min at 8000 rpm with a Silverson L4RT mixer. An Anton Paar MCR 92 rheometer with a CC 27 cup was used to measure the viscosity. Each sample was allowed to equilibrate to 25 C for 10 min. Samples were pre-sheared at a shear rate of 50 s−1 for 3 s and left for a further 3 min before measurement commenced. The samples were analysed at a shear rate of 0.01 s−1–100 s−1 .

Turbidity data was used to estimate the diameter size for the samples. This turbidity was determine using the absorbance at various wavelengths. Samples used were similar to those of the viscosity measurements, only difference is that the final concentration was 0.03 wt%. UV-Vis used is a Cary 60. Please refer to for the equation that was used to relate turbidity to fibre diameter.

The mechanical testing was of amura thermoplastic starch made with 30 % glycerol, relative to the mass starch. Film casting was used. All samples were prepared at 85 °C for 30 min with magnetic stirring. Samples were dried in a 50 °C oven. Various amounts of CNF and xanthan, both non-dried and dried, was added to the samples. All samples were conditioned at 54 % relative humidity for 10 - 14 days. These results showed what influence CNF, xanthan, and their interaction had on the tensile properties of the thermoplastic starch.


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