Effect of molecular structure on the gas permeability of cellulose aliphatate esters | SpringerLink
Handbook of Textile Fibre Structure: Natural, Regenerated, Inorganic and Specialist Fibres, Cellulose esters, besides cellulose esters of inorganic esters and cellulose ethers, were pioneer compounds of cellulose chemistry, and they remain the most important technical derivatives of cellulose Klemm et al. Unlike commodity plastics such as polyolefins, cellulose cannot be processed thermoplastically.
However, derivatization, that is, esterification, can yield materials suited for thermoplastic processing. Cellulose esters, such as cellulose acetate CA , cellulose acetate propionate CAP , and cellulose acetate butyrate CAB , are thermoplastic materials produced through the esterification of cellulose Mohanty et al. A variety of raw materials such as cotton, recycled paper, wood cellulose , and sugarcane are used in making cellulose ester biopolymers in powder form. Such powders combined with plasticizers and additives are extruded to produce various grades of commercial cellulosic plastics in pelletized form.
Of great interest as potential biodegradable plastics are also long-chain aliphatic acid esters of cellulose Edgar et al.
Cellulose esters are characterized by their stiffness, moderate heat resistance, high moisture vapor transmission, grease resistance, clarity and appearance, and moderate impact resistance Edgar et al. Some properties of commercial cellulose esters are given in Table Staiger, in Natural Fibre Composites , Cellulose in the nanometric form has tremendous potential as a component in bionanocomposites.
Methods are being developed for the production of nanometric cellulose via incorporation of cellulose into electrospun fibres or electrospinning the material itself. Electrospun cellulosic native and derivatised fibres, solution blending to incorporate cellulosics, use of cellulose nanofibres and nanocomposites based on cellulose nanofibres are reviewed, and electrospun cellulose nanofibres as reinforcing material are compared with other polymers.
This chapter gives a broad overview of activities related to electrospinning and cellulose and examines future trends in terms of cellulose -based nanocomposites and the role of electrospinning in their development. Cellulose is the most abundant organic compound in the world, which mostly produced by plants. In the market, it can be found with different mechanical and pharmaceutical properties, due to the range of shape, sizes, and degrees of crystallinity of their particles.
Some derivatives, such as ethyl cellulose , hydroxyethyl cellulose , hydroxypropyl cellulose , methylcellulose, carboxymethyl cellulose , hydroxypropylmethyl cellulose , and sodium carboxymethyl cellulose are used in bioadhesive preparations. Cellulose can be harvested from many plant sources as it is the major part of the cell wall.
Also cellulose can be produced by fermentation of certain bacteria. Fermentation occurs in a bioreactor and is the process of microorganisms metabolically breaking down organic substances in the absence of oxygen, anaerobic metabolism. Important parameters controlled during the process are temperature, pH, and sugar content from the feedstock material.
Fermentation can also be carried out with genetically engineered microorganisms GEMs. GEMs can be designed to break down specific substrate materials during fermentation, as well as surviving the harsh conditions .
Cellulose produced by bacteria can be obtained as a continuous film by cultivating the bacteria in a glucose solution . Cellulose is also secreted by marine chordates such as the sea squirt .
Cellulose from plant sources can be extracted by chemical solubilisation type processes such as pulping, which results in a refined structure. The cellulose structure is disrupted and the cellulose remaining in solution is then precipitated.
This method is used to prepare regenerated cellulose. Regenerated cellulose is different from native cellulose because extensive degradation takes place during the process of dissolution and the final product is usually less crystalline . Other products derived from cellulose include cellulose nitrate, cellulose ester, and cellulose acetate. Work has been conducted on grafting cellulose as copolymer, as well as the potential to cross-link cellulose.
There is interest in cellulose chemistry and polymerization due to the abundance of cellulose as a renewable resource. Cellulose , the most abundant organic compound on earth, is the major structural component of the cell wall of higher plants . Cellulose pulps can be obtained from many agricultural by-products such as sugarcane, sorghum bagasse, corn stalks, and straws of rye, wheat, oats, and rice.
The consequence of the supra-molecular structure of cellulose is its insolubility in water, as well as in common organic liquids [24,31]. Poor solubility in common solvents is one of the reasons why cellulose is converted to its cellulose esters. Another reason is that cellulose is not melt-processible, because it decomposes before it undergoes melt flow .
Cellulose esters have been commercially important polymers for nearly a century, and have found a variety of applications, including solvent-borne coatings, separation, medical and controlled release applications as well as composites and laminates, and plastics.
They are thermoplastic materials produced through esterification of cellulose. Different raw materials such as cotton, recycled paper, wood cellulose , and sugarcane are used to make the cellulose ester biopolymers in powder form.
Bioceta, plasticized cellulose acetate, is prepared from cotton flakes and wood pulp through an esterification process with acetic anhydride. Cellulose acetate propionate CAP and cellulose acetate butyrate CAB are mixed esters produced by treating cellulose with appropriate acids and anhydrides in the presence of sulfuric acid. Cellulose -based polymers are given in Table Cellulose is a linear organic polysaccharide comprised of many glucose monosaccharides with the chemical formula C 6 H 10 O 5 n.
Cellulose is a hydrophilic substance insoluble in water and most organic solvents. The structure of cellulose is chiral and the compound is biodegradable. It can be broken down chemically into its glucose units by treating it with concentrated acids at high temperature.
The characteristic beta acetal linkage in the cellulose structure differs from starch and is the major difference in digestibility in vertebras. Humans are unable to digest cellulose because the appropriate enzymes to break down the beta acetal linkages are lacking.
Cellulose is the main structural component of the primary cell wall of most plants, many forms of algae, and oomycetes. Some species of bacteria secrete cellulose to form biofilms. Cellulose is the most common organic compound on Earth.
For industrial use, cellulose is mainly obtained from wood pulp and cotton. It is mainly used to produce paper products such as cotton, linen, and rayon for clothes, nitrocellulose for explosives, and cellulose acetate for films.
An immerging use of cellulose is converting cellulose from energy crops into biofuels such as cellulosic ethanol for the study of alternative biofuel sources.
Sain, in Biofiber Reinforcements in Composite Materials , Cellulose biosynthesis is a multistep process that is highly specific to the organism producing the cellulose. Variations in this natural process dictate the morphology, aspect ratio, crystallinity and crystal structure of the resulting microfibril. As shown in Fig. The final stage involves the assembly of cellulose fibrils into either micro- or macrofibrils, depending on the organism plant, alga, tunicate, bacterium.
Radhakrishnan Narayanaswamy 1 3 , Parasuraman Padmanabhan 4 , in Nanobiomaterials in Medical Imaging , Cellulose is a linear polymer of glucose molecules and major component of the plant cell wall. Many researchers have reported on the preparation and characterization of cellulose nanoparticles. Acid hydrolysis is the most commonly employed method for the preparation of cellulose nanoparticles. Recently, curcumin-loaded cellulose nanoparticles have been reported for prostate cancer therapy.
Dong and Roman reported that fluorescein-5'-isothiocyanate FITC -labeled cellulose nanocrystals were used as a fluorescent agent for bioimaging. Recently, Jokerst et al. These include ethyl cellulose , hydroxy ethyl cellulose , methyl cellulose , sodium carboxy methyl cellulose , and benzyl cellulose. Ethyl and benzyl cellulose can be used as hot-melt adhesives. Methyl cellulose is a tough material, completely nontoxic, tasteless, and odorless, which makes it a suitable adhesive for food packages.
It is capable of forming high-viscosity solutions at very low concentrations, so it is useful as a thickening agent in water-soluble adhesives. Hydroxy ethyl cellulose and sodium carboxy methyl cellulose can also be used as thickeners. The cellulose ethers have fair to good resistance to dry heat.
Water resistance varies from excellent for benzyl cellulose to poor for methyl cellulose. Cellulose acetate butyrate CAB is a mixed ester of cellulose. CAB, commonly known as butyrate, is resistant to ultraviolet rays, has a lower moisture absorption than cellulose acetate, and has an extremely high-impact strength. Its CAS number is and the approximate chemical structure is shown in Fig.
Manufacturers and trade names: Tenite Cellulose Acetate Butyrate contains an odor mask and an ultraviolet inhibitor. Cookies are used by this site. For more information, visit the cookies page. Compostable Polymer Properties and Packaging Applications Ewa Rudnik, in Plastic Films in Food Packaging , Properties Cellulose esters, besides cellulose esters of inorganic esters and cellulose ethers, were pioneer compounds of cellulose chemistry, and they remain the most important technical derivatives of cellulose Klemm et al.
Electrospun cellulosic fibre-reinforced composite materials D. Staiger, in Natural Fibre Composites , Abstract: Nanostructured therapeutic systems with bioadhesive and thermoresponsive properties Marcos L.
The use of biobased nanofibres in composites S. Basics to different imaging techniques, different nanobiomaterials for image enhancement Radhakrishnan Narayanaswamy 1 3 , Parasuraman Padmanabhan 4 , in Nanobiomaterials in Medical Imaging , 4. Eastman Chemical Company Tenite: View full topic index.