Commercial cellulose powders

Our experimental work started from the following original cellulose samples (a) acetate-grade, bleached cotton linters, DP 1800 (b) hot, refined, spruce, sulphite-dissolving pulp, machine dried, ca. 93% a-cellulose, DP — 750 (c) never-dried, normal, rayon-grade, beech sulphite pulp, ca. 90% a-cellulose, DP = 825 (d) commercial cellulose powders obtained by hydrolytic degradation and/or mechanical disintegration of cotton linters or spruce sulphite pulp. 

The bulk density of cellulose acetate varies with physical form from 160 kg/m (10 lb /ft ) for soft dakes to 481 kg/m (30 lb /fT) for hammer-milled powder, whereas the specific gravity (1.29—1.30), refractive index (1.48), and dielectric constant of most commercial cellulose acetates are similar. 

Technique of thin-layer chromatography. Preparation of the plate. In thin-layer chromatography a variety of coating materials is available, but silica gel is most frequently used. A slurry of the adsorbent (silica gel, cellulose powder, etc.) is spread uniformly over the plate by means of one of the commercial forms of spreader, the recommended thickness of adsorbent layer being 150-250 m. After air-drying overnight, or oven-drying at 80-90 °C for about 30 minutes, it is ready for use. 

Method 1 (cellulose layers). The cellulose powder is washed twice with isopropanol-ammonium hydroxide-water (6 3 1), washed once in isopropanol and dried at 10S °C for 8 h. The plates (thickness, 0.25 mm) are prepared with a commercial TLC applicator. The slurry consists of 15 g of prepared cellulose in 85 ml of water which has been homogenized in a blender. The plates are dried at room temperature, and then eluted with diethyl ether in order to remove organic impurities. The plates are dried in air immediately before use. The pesticides are spotted and developed with appropriate solvent systems. The chromatoplate is dried in air and sprayed lightly with a 0.05% solution of fisetin in isopropanol. The separated spots are observed visually under a UV light at 365 nm (excitation, 370 nm emission, 533 nm). This method has been examined for several types of pesticides including carbamates, organophosphates, triazines and chlorinated hydrocarbons. 

Materials. Commercial cotton (Pakistani cotton) cut into 5 mm length and Whatman cellulose powder CF-11 was used as cellulose samples after Soxhlet extraction with alcohol-benzene for 7 h. Wood meal (mainly 40 - 80 mesh) from Makanba (Betula Maximowicziana Regel) was used after washing with cold water. Methyl methacrylate and styrene were purified by the conventional methods. Other reagents used were analytical reagent grade. 

The overall method on which most of the preparation of immunoadsorbent is based is that of Gurvich et al. (Fig. 4). The initial preparation of cellulose powder can be carried out by refluxing cotton wool with ethanol and acetyl chloride. However, a more convenient alternative is to use commercially available microgranular cellulose (Whatman Ltd., Springfield MUl, Maidstone, Kent). Five grams of cellulose are suspended in 20 ml of 90% ethanol containing 0.5 g of sodium acetate and 1.4 g of nitrobenzyloxymethyl pyridinium chloride (British Drug House, Poole, Dorset, U.K.). Sodium acetate is dissolved first in 2 ml of water, and the... 

A number of different grades of lactose are commercially available that vary in their physical properties and many studies have been reported in the literature comparing the behavior of these various materials in different formulations. A number of co-processed excipients which contain lactose are available for direct-compression applications co-processed lactose and starch (Starlac, Meggle/Roquette Freres), lactose and microcrystalline cellulose Microcelac, Meggle) lactose and cellulose powder (Cellactose, Meggle), lactose, povidone, and crospovidone (Ludipress, BASF). 

Figure 2. Distribution of protein and enzymic activities after gel filtration of a partly purified commercial enzyme powder (Cellulose 36, Rohm Haas Co., Philadelphia) on two connected Sephadex G-75 columns. The void volume of the system was 1170 ml. The fraction volume was 27 ml. (2)...

Cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB) are thermoplastic materials produced through esterification of cellulose and are used for many packaging applications. Different raw materials such as cotton, recycled paper, wood cellulose, and sugarcane are used in the production of cellulose ester biopolymers in powder form. Such cellulose ester powders in the presence of different plasticizers and additives are extruded to produce various grades of commercial cellulose plastics. Recently, Misra et al. successfully used melt intercalation technique for the fabrication of cellulose nanocomposites and studied the effect of C30B on its performance characteristics [44]. From the study, the... 

Kumar et al. [83] studied the weathering properties of ethylene-propylene copolymer (EPC) matrix composites with three different reinforcement materials, namely, 3% NaOH-treated jute fibers, 17.5% NaOH-treated jute fibers and commercial microcrystalline cellulose powder, using maleated EPC as a compatibilizer. The samples were subjected to UV radiation at 60°C in air for 150 hours. Again, the neat polymer samples were more resistant to weathering than the composites. The samples reinforced with commercial microcrystalline cellulose were the most stable of the composites and those made with fibers treated with the lower concentration of NaOH were the most susceptible to photo-oxidation. It was concluded that optimizing the durability and mechanical properties of the natural fiber-reinforced composites was closely dependent on selecting the appropriate treatment for the fibers. 

Thin-layer applications have called for the selection of the finest resin or modified cellulose particles in order to increase the surface area and insure maximum contact between particles in the thin layer. The addition of inert binders to promote the adherence of the coarse resin particles to the glass plate has met with less success. The best thin-layer plates of anion-exchange resins have been obtained by impregnating fine cellulose powders with liquid anion-exchange resins such as the polyethylenimine (17). The latter material is commercially available with a particle size of approximately 10 jx and an ion-exchange capacity of about 1.0 meq/g. 

Table 8. Summary of the usual commercial types of cellulose powder for TLG...

Layers of cellulose ion-exchangers are prepared with the usual commercial spreaders. A mixture is made of water or the solvent to be used, and about 10—20% cellulose powder. The amount of powder depends on the swelling tendency of the particular powder. The exchangers CM-, DEAE- and ECTEOLA-ceUulose tend to swell considerably PEI- and Poly-P-cellulose only slightly. This swelling is disadvantageous in that the completely dry layer shows a greater or lesser number of very fine cracks. 

PLA Poly(lactic acid) commercial sample from Mitsui Chemicals Composting (ISO 14855-1, ISO 14855-2, enzymatic degradation) CO2 evolution measurement based on titration and gravimetric methods Biodegradation of PLA powder was 91% for 31 days (ISO 14855-1 method) and 80% for 50 days at 58°C (ISO 14855-2 method) Cellulose powder was used as reference material PLA in the form of powders of different size was used [17]... 

Polysaccharides can be oxidized even by such a mild oxidant as atmospheric oxygen. The rate of oxidation is greatly enhanced by alkalies and by various heavy metal ions. Mild oxidations are beneficial when properly employed for producing new and useful properties in polysaccharides. As an example, starch is mildly oxidized by small amounts of bleaching powder to produce improved textile sizes. Atmospheric oxidation of alkali-treated cellulose reduces the chain length of commercial cellulose to the point where its xanthate can be dissolved in a strong alkaline solution and can be used... 

Cellulose layers. Cellulose powder (1S g) is mixed with distilled water (100 ml) and homogenized in a blender for 30 s. The slurry is transferred to the plates with a commercial spreader unit. The plates are allowed to dry for 6 h. 

Nature uses cellulose primarily as a structural material to impart strength and rigidity to plants. Leaves, grasses, and cotton, for instance, are primarily cellulose. Cellulose also serves as raw material for the manufacture of cellulose acetate, known commercially as acetate rayon, and cellulose nitrate, known as guncotton. Guncotton is the major ingredient in smokeless powder, the explosive propellant used in artillery shells and in ammunition for firearms. 

The late 19th century saw the development of a new family of "smokeless" powders, as modern organic chemistry blossomed and the nitration reaction became commercially feasible. Two "esters" - nitrocellulose and nitroglycerine - became the major components of these new propellants. An ester is a compound formed from the reaction between an acid and an alcohol. Figure 6.1 illustrates the formation of NC and NG from nitric acid and the precursor alcohols cellulose and glycerine. 

Five types of commercial EtCell were manufd during WWII by the Hercules Powder Co (Ref 2), of which the N-Type, having 46.8 to 48.5% ethoxyl content, bad sp gr 1.14, mp 200—210° and the same requirements as were listed in USArmySpecification No 97—54—176, now replaced by Spec MIL-E-108 53 B. The product is more resistant to alkali solns than to the acids. Its flammability is of as low an order as any other cellulosic derivatives (Ref 2)... 

---