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Cellulose – A Sustainable Material for Biomedical Applications
Published in Ashwani Kumar, Mangey Ram, Yogesh Kumar Singla, Advanced Materials for Biomechanical Applications, 2022
N. Vignesh, K. Chandraraj, S.P. Suriyaraj, R. Selvakumar
Cellulose derivatives come under the group of soluble cellulose polymers. These are associated with properties like biocompatibility, biodegradability and low toxicity similar to CNCs and CNFs. However, cellulose is converted to different products like cellulose acetate, cellulose sulfate, cellulose nitrate and carboxymethyl cellulose using chemical treatments (Table 4.2). The degree of substitution and derivatization of cellulose depends on the process conditions [57]. Cellulose acetate is produced by acetylation of cellulose using acetic anhydride in the presence of sulfuric acid as a catalyst [33]. Cellulose acetate has been combined with hydroxyapatite to synthesize a composite membrane by the electrospinning process (Figure 4.4a). The composite has also been used as a hemodialysis membrane [58].
Plastics materials and rubbers
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
This very dangerous ‘nitrate’ film has since been replaced by cellulose acetate (CA) for this, and other purposes, since CA is virtually non-flammable. Although only moderately strong and tough, CA is fairly cheap and is used for moulding a wide range of articles from pens and pencils to toys and toothbrush handles.
Naturally Occurring Polymers—Plants
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
While other organic esters are commercially available, namely, cellulose butyrate and cellulose propionate, by far the most widely used one is cellulose acetate. Cellulose acetate is available as plastics, in films, sheets, fibers, and lacquers. Cellulose acetate is used in the manufacture of display packaging and as extruded film for decorative signs, and to coat a variety of fibers. Injection-molded products include toothbrush handles, combs, and brushes. It is also used in lacquers and protective coatings for metal, glass, and paper. Cellulose acetate films are used in reverse osmosis to purify blood, fruit juices, and brackish water. Some eyeglass frames are made of cellulose acetate. Biodegradable film, sponges, and microencapsulation of drugs for controlled release also utilize cellulose acetate. Cellulose triacetate is used for photographic film bases. Numerous continuous filament yarns, tows, staples, and fibers are made from cellulose acetate. The precise form of filament produced is controlled by a number of factors, including the shape of the die. Table 9.6 presents representative physical properties for cellulose acetate.
Photo-responsive azo-functionalised flexible polymer substrate for liquid crystal alignment
Published in Liquid Crystals, 2020
B. Sivaranjini, K. Mohana, S. Esakkimuthu, V. Ganesh, S. Umadevi
The present work describes a simple and reproducible technique for chemically attaching an azobenzene derivative containing a dimethylchlorosilane end group onto a cellulose acetate containing flexible polymer substrate via hydrosilation reaction. Chemical functionalisation of the flexible film with azo-compound is carried out to create permanent photoalignment layers on the flexible substrate surface. The cellulose acetate containing flexible polymer films have unprecedented properties such as light-weight, low-cost, thinness, chemical compatibility, good thermal and chemical stability, transparency, high mechanical strength and easy availability. The activation energy for the photoisomerisation of azobenzene derivative containing a dimethylchlorosilane end group was determined in solution by UV-visible spectroscopy. The chemical functionalisation of the polymer substrate was confirmed using a combination of X-ray photoelectron spectroscopy (XPS), attenuated total reflectance infrared (ATR-IR) spectroscopy, contact angle (CA), atomic force microscopy (AFM) and UV-diffuse reflection spectroscopy (UV-DRS) techniques. Following the confirmation of successful surface functionalisation, the azo-modified flexible substrate was studied for the bulk LC alignment and the subsequent photo-induced reorientation of the LCs.
Solvent-free acetylation of Ensete ventricosum plant fibre to enhance oleophilicity
Published in The Journal of The Textile Institute, 2022
Mangesh D. Teli, Jelalu M. Terega
Acetylation is a simple esterification process that enables to modify the properties of natural plant fibres through which hydroxyl functional groups on anhydroglucopyranose units of cellulose chains react with acetic anhydride to produce cellulose acetate. The process can be undertaken in homogeneous or heterogeneous conditions. During the reaction, a homogeneous system requires suitable solvents such as ionic liquid or lithium chloride/dimethylacetamide to dissolve the cellulose whereas a heterogeneous system needs an insoluble medium such as toluene, benzene, or amyl acetate (Zhou et al., 2016). While increasing hydrophobicity and oleophilicity, acetylation of cellulosic and lignocellulosic materials diminishes the number of hydroxyl groups remaining in the polymer systems.
Characterization and mechanical properties of electrospun cellulose acetate/graphene oxide composite nanofibers
Published in Mechanics of Advanced Materials and Structures, 2019
Nada M. Aboamera, Alaa Mohamed, Ahmed Salama, T.A. Osman, A. Khattab
In the recent few decades, nanotechnology has become the major field of research because of its variety of applications. Consequently, electrospinning technology is used to obtain ultrafine nanofibers and nanocomposite fibers with diameters ranging between a few micrometers and nanometers, which have a uniform morphology. Electrospinning is an effective, simple, and versatile technique with low cost. The most common applications of electrospun nanofibers include filters, textiles, drug delivery, sensors, environmental, catalysis, and tissue engineering [1]–[6]. Cellulose was used to fabricate nanofibers as it is an available polymer having a biodegradable nature and excellent properties [7]. Cellulose acetate (CA) is used due to its mechanical properties, potential compatibility, and its various applications, such as laminates, fibers adhesives, films, etc. [8]–[12]. In order to improve the mechanical properties, electrical conductivity, and thermal stability of composite nanofibers, hydrophilic graphene oxide (GO) is used that forms CA/GO composite nanofibers [13]. The mechanical properties were affected by several parameters, such as the material selection, varying solution composition, altering processing parameters, or utilizing postspinning treatments. In addition, optimization of electrospinning conditions is required to improve the mechanical properties of the composite nanofibers and increase the application variety. Moreover, the modulus and strength of the materials depend on fiber orientation within the material, slip of one fiber over another, and bonding between fibers. The mechanical properties are usually obtained only for yarns or mats rather than for individual fibers because of the small diameters of electrospun fibers [14].