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Electrospinning was used to fabricate ethyl-cyanoethyl cellulose [(E-CE)C] fibers from tetrahydrofuran (THF) solutions. It was found that the solution jet is split or atomized during the flight to the grounded collector. Microcavities were detected on the surface of the fibers and these were attributed to the volatilization of the solvent (THF). The thinnest fibers generated had a diameter of about...
The supermolecular structure of dissolving pulps produced from hardwood by the organosolv processes Acetosolv, Formacell, and Milox was characterized by physical methods (TEM, WAXS, SAXS, NMR) and compared with conventional Sulfite and standard commercial dissolving pulps. The suitability of the pulps for the NMMO technology was tested by spinning fibres and blowing films, whose structural and mechanical...
The structure and morphology of cellulose extracted from wheat were studied. It was found that the extraction process is effective and hemicelluloses and lignin can be extracted completely. Cellulose in wheat straw was identified as cellulose I allomorph with low crystallinity and the crystallinity of cellulose from different parts of the wheat straw has little difference. There was no metastable...
The structure and morphology of cellulose extracted from wheat were studied. It was found that the extraction process is effective and hemicelluloses and lignin can be extracted completely. Cellulose in wheat straw was identified as cellulose I allomorph with low crystallinity and the crystallinity of cellulose from different parts of the wheat straw has little difference. There was no metastable...
Natural fibers in micro and nano scales may be a potential alternative for man-made fibers because of the comparable mechanical properties to those of glass, carbon, and aramid fibers. Cellulose fibril and fibril aggregate are generally prepared by physical treatments, e.g., high-pressure homogenizer, or chemical treatments, e.g., acid hydrolysis. In this study, fibril aggregates were generated from...
In the last years several composites and high performance materials with woody and non-woody natural fibers have been developed. In this study, a morphological study of agricultural residues as rachis from Musaceae plants cultivated in Colombia has been carried out. Fibrous structures as fiber bundles, elementary or ultimate fibers and even cellulose microfibrils grouped together into microfibril...
The precipitation in aqueous media of cellulose from solutions in N-methylmorpholine N-oxide (NMMO) hydrates is an important stage in the process of manufacturing of fibres, films and other cellulose objects. It is responsible for the formation of the structure of the regenerated object and their morphological characteristics significantly influence the properties of the final products. Regeneration...
To understand the effect of alkali pre-treatment on the dyeing of lyocell fabrics, samples are pre-treated with 0.0–7.0 mol dm−3 NaOH using a pad-batch process and then dyed with different types of reactive dyes. Exhaustion, fixation, and visual colour strength (K/S values) are measured. It is observed that sodium hydroxide pre-treatment significantly improves the colour yield, exhaustion, and fixation...
The kinetics of cellulose regeneration in acetic acid bath from cellulose–8% NaOH–water solutions and gels is studied as a function of gelation conditions, acid concentration and bath temperature. The diffusion coefficient of NaOH from cellulose solution or gel into regenerating bath was calculated. It does not depend either on gelation mode or on acid concentration. On the contrary, cellulose regeneration...
The objective of this study was to prepare nanocomposites based on polyphenols and nanocellulose fibers using relatively benign processing. To accomplish this, phenol was polymerized using horseradish peroxidase in the presence of TEMPO-oxidized nanocellulose. The polyphenol-nanocellulose composite was insoluble in organic solvents but the individual components were soluble. SEM imaging of fracture...
Bionanocomposites of hydroxypropyl cellulose (HPC) and nanofibrillated cellulose (NFC) were prepared by solution casting. The various NFC were in form of powders and were prepared from refined, bleached beech pulp (RBP) by mechanical disintegration, optionally combined with a pre- or post mechanical carboxymethylation. Dynamic mechanical analysis (DMA) and tensile tests were performed to compare the...
Cellulose whiskers were prepared from wood- and cotton-based microcrystalline cellulose and dried by two methods: freeze-drying or air-drying. The effect of drying method on the properties and structure of the whiskers were studied. Furthermore, the influence of the source of cellulose on the nanoscale structure was investigated. Drying method was observed to slightly influence the thermal stability...
Hybrid organic–inorganic coatings containing ammonium polyphosphate (APP), chitosan and silica have been deposited on polyester-cotton blends (PET-CO), exploiting the layer by layer assembly. To this aim, two different complex architectures (namely, chitosan/APP bilayers plus silica/silica bilayers or silica/silica/chitosan/APP quadlayers) have been thoroughly investigated. The effect of their morphologies...
Cellulose whiskers were obtained by means of sulfuric acid hydrolysis of curauá fibers. Before hydrolysis, the natural fibers were treated with an alkaline solution to remove the non-cellulosic content. Fiber degradation evolution and cellulose whisker formation were analyzed by structural and morphological analysis. The original fiber structure underwent a fragmentation mechanism after being exposed...
Microcrystalline cellulose (MCC) and spherical nanocrystalline cellulose (SNCC) were successfully prepared from waste cotton fabrics through acid hydrolysis. The comparative analysis of the morphology and structure between the obtained MCC and SNCC was carried out. The SNCC suspension exhibited higher stability than the MCC suspension. Transmission electron microscopy in combination with atomic force...
This study reports the production of cellulose nanofibrils (CNF) from a bleached eucalyptus pulp using a commercial stone grinder. Scanning electronic microscopy and transmission electronic microscopy imaging were used to reveal morphological development of CNF at micro and nano scales, respectively. Two major structures were identified: (1) highly kinked, naturally helical, and untwisted fibrils...
Flexible composite films were produced by impregnating aqueous phenol formaldehyde (PF) resin into water-swollen cellulose nanofibril (CNF) films. CNF films were prepared using a pressurized filtration method in combination with freeze drying. The freeze-dried films were swollen with water then impregnated with PF resin by soaking in aqueous resin solutions of varying concentrations. Small amounts...
This paper deals with the effect of different montmorillonite source clays, including pristine and organophilic montmorillonites, on the structure, morphology and properties of cellulose acetate (CA)/clay nanocomposites. In this study, the nanocomposites were prepared by melt extrusion in the presence of the environmentally friendly triethyl citrate plasticizer. The structure and morphology of the...
Cellulose nanocrystals (CNC) prepared from eucalyptus cellulose CNCs were modified by the reaction with methyl adipoyl chloride, CNCm, or with a mixture of acetic and sulfuric acid, CNCa. The CNC were either dispersed at 0.1 wt% in the pure solvents ethyl acetate (EA), tetrahydrofuran (THF) and dimethylformamide (DMF) or in cellulose acetate butyrate (CAB) solutions prepared in these solvents at 0...
Fourteen cotton samples of various strength, maturity and fineness were compressed in the same conditions at elevated pressure (2.0 GPa) and temperature (120 °C) in a home-made Bridgman anvil press designed to process samples of about 20 mm diameter. The influence of cotton properties to the abilities to be compacted into a solid 3D object was studied by mechanical measurements (nano-indentation and...
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