Cellulose ester table

From 1980 to 1988, aimual cellulose acetate flake production in the United States showed a slight decrease in production from 392,000 t to 323,000 t with an aimual decline of —0.4 to —0.1% (Table 6). World demand for cellulose acetate flake has also fallen. A modest recovery has occurred in recent years as a result of the increased demand for cigarette-filter tow world consumption of cigarette-filter tow has risen about 2.5% per year since 1980 (Tables 7 and 8). In contrast, world demand for textile fibers and cellulose ester plastics decline 4.6% and 4.2% per year, respectively (Fig. 9). 

The cellulose esters with the largest commercial consumption are cellulose acetate, including cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate. Cellulose acetate is used in textile fibers, plastics, film, sheeting, and lacquers. The cellulose acetate used for photographic film base is almost exclusively triacetate some triacetate is also used for textile fibers because of its crystalline and heat-setting characteristics. The critical properties of cellulose acetate as related to appHcation are given in Table 10. 

Higher butyryl esters, formulated with acryUc polymers, provide coatings with excellent weather resistance, good colorfastness and dispersibiUty, and good flow properties (154). Formulations for a typical automotive refinishing lacquer and a wood furniture lacquer are given in Tables 12 and 13, respectively. Low viscosity, high butyryl cellulose esters tolerate substantial amounts of alcohol solvent without appreciable increase in solution viscosity. 

Sampling and Analytical Precision and Accuracy. The accuracy of results obtained from a sampling and analytical method are determined by comparison with an independent method. The aerosols of phosphoric and sulfuric acids were collected on mixed cellulose ester filters (14 ) and analyzed by ion chromatography. Table V shows the collection efficiency of the 7-mm O.D./700-mg silica gel collection tubes with respect to the results obtained from filter samples, and the precision obtained from calculation of the pooled relative standard deviation. 

Table II. Stability at room temperature of aqueous extracts of spiked cellulose ester filters as a function of time.

In point of fact it has been established by many workers that a nitrocotton freshly produced and washed from acid could contain up to 8% of sulphuric add cellulose esters. Berl and Boltenstem [7] stated in later investigations that sulphuric add always occurred in the stabilized nitrocotton in two forms (a) as an inorganic salt, for the most part CaS04 (b) as sulpho groups chemically combined with cellulose. Their data are given in Table 62. 

Most experiments were performed with cotton or cotton linters as highly crystalline celluloses. Table I shows conditions leading to complete dissolution. A minimum amount of an acid which forms a cellulose ester (sulfuric or trifluoromethylsulfuric acid) (Entries 5 7-14) is necessary for the reaction. The dissolution is accelerated by a temperature increase (Entries 10-12 13, 14) and leads to water-soluble cellulose acetate hydrogensulfate. Whereas this primary hydrolysis can be achieved within 1-5 min, the deesterification and complete hydrolysis of the soluble cellulose derivative proved to be much more difficult. This is in contrast to the generally accepted view that the main resistance to the hydrolysis of cellulose lies in the crystalline nature or low accessibility determining the heterogeneous first step of the reaction. 

The major use of ultraviolet light absorbers is in polyolefins, polyvinyl chloride), polyesters, cellulose esters, and polystyrene, as Table III indicates. Lesser quantities are used in polyamides, acrylics, polyacetals, and polyurethanes. 

Chromium. Chromium is not an easily analyzed element because three distinct standards are listed by OSHA (Tables IV and V ). One standard exists for hexavalent chromium, chromic acid and chromates, another standard for soluble chromium compounds and chromous salts, and another standard for insoluble chromium compounds and chromium metal. The permissible amount of chromium in air decreases as the oxidation state increases. The analysis of chromium is further complicated by the multiplicity of NIOSH methods for chromium compounds. Hexavalent chromium shall be collected on PVC filters, although a criteria document for chromic acid (14) specifies mixed cellulose ester filters. The analytical method described in the hexavalent... 

In some cases, the rate-controlling polymeric membrane is not compact but porous. Microporous membranes can be prepared by making hydrophobic polymer membranes in the presence of water-soluble materials such as polyethylene glycol), which can be subsequently removed from the polymer matrix by dissolving in aqueous solution. Cellulose esters, loosely cross-linked hydrogels and other polymers given in Table 4.2 also give rise to porous membranes. 

Additional information on physical and chemical properties of cellulose esters is summarized in Table V. 

Table V. Physical and Chemical Properties of Cellulose Esters...

Table 2 Commercially Available Important Cellulose Esters and Ethers...

Threshold volume fractions observed for cellulose acetate (CA and CTA), ethyl cellulose (EC) and hydroxypropyl cellulose (HPC), each in various solvents, are presented in Table 3. The results depend to some extent on the solventThe data included are not exhaustive. Other cellulose esters exhibit mesomorphic behavior Chanzy et al. observed mesomorphic behavior in solutions of cellulose itself when dissolved in N-methylmorpholine N-oxide containing water at concentrations of cellulose in the range 20-55 % w/v, depending on the temperature, the water content of the solvent and the degree of polymerization of the cellulose. Solutions of cellulose in mixtures of trifluoroacetic acid with 1,2-dichloroethane or with chloroform are hkewise lyotropic at concentrations of 20% (w/v) and above according to Patel and Gilbert... 

Table L Length of the Kuhn segment A and chain diameter d for cellulose esters and ethers according to the data of sedimentation - diffusion studies and viscometry... 

Microcrystalline cellulose II, like the cellulose I form, does not possess enough mechanical strength to be used as an HPLC-CSP Although its triacetate derivative, CTA-II, can be used as an HPLC support, it is not as useful a CSP as CTA-I (47). Ichida et al. (48) were able to improve on the properties of derivatized cellulose II by depolymerization, followed by coating on macroporous silica gel. In this manner, they created a number of new CSPs, the cellulosic CSPs, based on ester and carbamate derivatives of cellulose (see Table 2). 

The two primary categories of cellulose derivatives, cellulose esters and cellulose ethers, which dominate the markets for cellulose derivatives (O Table 8), have somewhat different raw material requirements. Whereas both types of modification technologies prefer to start with chemical cellulose of high a-cellulose content, ethers give preference to molecular weight considerations while esters are sensitive to impurities. This is a consequence of the predom-... 

Epichlorohydrin or chloromethyloxirane is manufactured from allyl chloride, and, in 2006, had a merchant price of US 1.66 kg [4]. It is used as a building block in the manufacture of plastics, epoxy resins, phenoxy resins, and other polymers, and as a solvent for cellulose, resins, and paints, and has also found use as an insect fumigant. Epoxy resins (aryl glycidyl ethers) are manufactured successfully in large scale (1.2 x 10 metric tons in 2000) [26] and are widely used in a variety of industrial and commercial applications [27]. These are made by addition reactions of epichlorohydrins or by epoxidation of allyl ethers or esters (Table 1.1). Epichlorohydrin can be reacted with an alkali nitrate to produce glycidyl nitrate, an energetic binder used in explosive and propellant compositions. 

The overall effect of the radicals of the substituents can be assessed by comparing the dissociation constants of the corresponding substituted acids data on the degree of substitution of various cellulose esters prepared by the trans-esterification reaction are presented in Table 11. 

Air samples of the workplace should be taken using calibrated sampling pumps with cassettes that contain either mixed cellulose ester (MCE) or polyvinyl chloride (PVC) filters. There may be a number of country-specific statutory sampling requirements. The guide shown in Table 16.1 provides an overview of the effectiveness of control measures. 

In the United States, a wide range of organic acid esters of cellulose are marketed for the coatings industry (Table I). While some are used without modification, such as CA-398-10 for flashbulb coatings, most cellulose esters are employed as modifying resins in multicomponent coating formulations. 

In some instances such as in isocyanate cross-linked coatings, the amount of moisture present must be taken into account in formulating calculations. Cellulose esters are packaged with very low moisture content however, if exposed to the atmosphere, cellulose ester powder or flake will regain moisture. The amount gained is dependent upon the relative humidity and the cellulose ester type, as illustrated in Table III. To ensure a consistent composition, all cellulose esters should be stored in low relative humidity surroundings or kept in a closed container. 

Viscosity Blending. As shown in Table I, a wide range of cellulose esters are commercially available. Each type may be identified by acetyl content alone, as in the case of cellulose acetate, or, for mixed esters, by the weight percent of the ester contributed by butyryl or propionyl groups following acylation. Further... 

Table III. Moisture Regain of Cellulose Esters upon Storage ...

Cellulose esters and ethers of various types and viscosities are characterized by their degree of substitution (DS), i.e. the average number of substituted hydroxyl groups (the maximum value is 3, see also Table 3). Furthermore, ethers or ether esters with hydroxyalkyl groups attached are characterized by the degree of reaction (DR), also frequently named molar substitution (MS), i.e. the average number of molecules of reagent (alkylene oxide) reacted with each... 

The H and C chemical shifts and assignments (based on the 2D NMR analyses) are given in Table I. The assignments of the acrylates and methacrylates have been published a recent review with spectra is by Brandolini and Hills (but note the backbone assignments in the acrylates and methacrylates are reversed and the OCHj protons misassigned in m in this reference) (4), The H and C assignments for cellulose esters has been described in a recent review by Lowman (5), We obtained spectra of CAB in acetone the chemical shifts and degeneracy observed in the H spectrum in this solvent are different than those in reference 5, but the order of shifts is the same. 

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