High-definition
automated optical analysis was used to observe
the morphological changes of bleached hardwood dissolving pulp during
oxidation mediated by (2,2,6,6-tetramethylpiperidn-1-yl)oxyl (TEMPO).
The effects of TEMPO treatment kinetics on fiber morphology and fibrillation
degree at a constant reagent loading were studied. The pulp underwent
significant swelling, and carboxyl groups were introduced in which
the fiber cell walls loosened, which contributed to fibrillation and
subsequently nanocellulose dispersion quality in terms of both viscosity
and visible light transmittance. The use of an automated optical fiber
analyzer facilitates process control, as it allows controlling the
fiber morphology and preventing major losses in the form of pulp fines
stemming from an unnecessarily long TEMPO oxidation time.
All-cellulose composites (ACCs) are manufactured using only cellulose as a raw material. Biobased materials are more sustainable alternatives to the petroleum-based composites that are used in many technical and life-science applications. In this study, an aquatic NaOH-urea solvent system was used to produce sustainable ACCs from wood-based woven textiles with and without the addition of TEMPO-oxidized nanocellulose (at 1 wt.-%). This study investigated the effects of dissolution time, temperature during hot press, and the addition of TEMPO-oxidized nanocellulose on the mechanical and thermal properties of the composites. The results showed a significant change in the tensile properties of the layered textile composite at dissolution times of 30 s and 1 min, while ACC elongation was the highest after 2 and 5 min. Changes in hot press temperature from 70 °C to 150 °C had a significant effect: with an increase in hot press temperature, the tensile strength increased and the elongation at break decreased. Incorporating TEMPO-oxidized nanocellulose into the interface of textile layers before partial dissolution improved tensile strength and, even more markedly, the elongation at break. According to thermal analyses, textile-based ACCs have a higher storage modulus (0.6 GPa) and thermal stabilization than ACCs with nanocellulose additives. This study highlights the important roles of process conditions and raw material characteristics on the structure and properties of ACCs.
Nanocelulozni hidrogeli so med najbolj perspektivnimi materiali z visoko dodano vrednostjo, ki jih je moč pridobiti iz celuloznih virov. V tem prispevku so predstavljeni postopki izdelave hidrogelov, ki temeljijo na nanocelulozi, ter njihova potencialna uporaba in varnostni vidik. V prihodnosti bodo namreč nanocelulozni materiali eni vodilnih produktov, ki bodo izhajali iz gozdno lesnega sektorja zaradi njihove visoke dodane vrednosti in potenciala za zamenjavo sintetičnih materialov.
Drug release profiles of novel alkane-crosslinked nanocellulose hydrogels were investigated. The common antiseptic compound chlorhexidine digluconate (CHX-DG) was loaded into the nanocellulose hydrogels, and the release kinetics were studied under two different release regimes. The hydrogels were effective at absorbing more than their dry weights of the antiseptic and retaining it during diffusion testing, with more than 60% of the drug retained in the hydrogels. Antimicrobial tests showed sustained antimicrobial activity of the CHX-DG-loaded hydrogels even after the two diffusion tests, which was attributable to non-ionic retention of the CHX-DG within the hydrogel structure.
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