Effect of DMDHEU treatment on properties of bacterial cellulose material

Abstract

The aim of this study was to estimate the influence of purification and treatment with textile finishing agent procedures on structural, mechanical, and water barrier properties of bacterial cellulose (BC) in order to predict the end-use properties. Kombucha fungus generated by Komagataeibacter xylinus species, formerly known as Gluconacetobacter xylinus, was used to produce the BC material. The BC was purified with 0.5% sodium hydroxide (NaOH) solution and treated with 5%, 10%, and 20% concentration of N, N-dimethylol 4,5-dihydroxy-ethylene urea (DMDHEU). By Fourier transform spectroscopy (FTIR) and X-ray diffractometer (XRD) was estimated, that the purification with a weak alkali solution was effective to remove amorphous matter of the BC material. Scanning electron microscope (SEM) images demonstrated the BC structure, similar to a non-woven textile fabric with clearly visible three-dimensional networks of fine cellulose fibers. After the purification process, the BC material tensile strength increased by 52%; however, the strain decreased by 93%. BC material after treatment with 20% DMDHEU regained deformability and tensile properties analogous to untreated samples. Water vapor permeability (WVP) values increased and water absorption capacity (WAC) decreased in BC material with increasing DMDHEU concentration. According to the FTIR results, the crosslinking reaction of DMDHEU and adjacent BC molecules was proved. The treatment with DMDHEU restores the amorphous properties of BC material, and therefore blocks water absorption, and the decrease in the water absorption parameter might be determined.