Cellulose volatilization

The gas phase contains inert gas from the original pores in cellulose, volatile from the primary decomposition, the second tar from the secondary reaction and permanent gas from both of the above two reactions. The flow of this gaseous mixture is driven by... 

A reaction coulometer has been used to determine the rate of heat release from these combustible volatiles (65). Table VIII shows these results on the effect of inorganic additives that were obtained by using reaction coulometry. The treated cellulose samples decomposed at lower temperatures and produced less heat than the untreated. Addition of 5% NaOH reduced the heat of combustion of cellulose volatiles at 500 °C to less than one-half of untreated (65). 

Citric acid cycle acids Strong cation exchange resin acid elution no regeneration Anion exchange chromatography (beaded DEAE--cellulose) volatile ethanol-formic acid eluents Turkelson and Richards [104] Bruinsma and Le Tourneau [116]... 

Continuous deaeration occurs when the viscose is warmed and pumped into thin films over cones in a large vacuum tank. The combination of the thinness of the Hquid film and the dismption caused by the boiling of volatile components allows the air to get out quickly. Loss of water and CS2 lower the gamma value and raise the cellulose concentration of the viscose slightly. Older systems use batch deaeration where the air bubbles have to rise through several feet of viscose before they are Hberated. 

Antimony Oxide as a Primary Flame Retardant. Antimony oxide behaves as a condensed-phase flame retardant in cellulosic materials (2). It can be appHed by impregnating a fabric with a soluble antimony salt followed by a second treatment that precipitates antimony oxide in the fibers. When the treated fabric is exposed to a flame, the oxide reacts with the hydroxyl groups of the cellulose (qv) causing them to decompose endothermically. The decomposition products, water and char, cool the flame reactions while slowing the production and volatilization of flammable decomposition products (see Flaa retardants for textiles). 

Fig. 9. SEM photographs of cellulose acetate membranes cast from a solution of acetone (volatile solvent) and 2-meth5l-2,4-pentanediol (nonvolatile solvent). The evaporation time before the stmcture is fixed by immersion ia water is shown (24).

Of these dimethyl phthalate (DMP) is used in most compositions. It is cheap, has a high compatibility with secondary cellulose acetate and is efficient in increasing flexibility, toughness and the ease of flow at a given temperature. Its principal disadvantages are its high volatility and the fact that it increases the flammability of the compound. Similar in compatibility but rather less volatile is diethyl phthalate. This material has less of an influence on flexibility and flow properties than the methyl ester. 

Triphenyl phosphate is a crystalline solid which has less compatibility with the polymer. This may be expected from solubility parameter data. It is often used in conjunction with dimethyl phthalate and has the added virtues of imparting flame resistance and improved water resistance. It is more permanent than DMP. Triacetin is less important now than at one time since, although it is compatible, it is also highly volatile and lowers the water resistance of the compound. Today it is essential to prepare low-cost compounds to allow cellulose acetate to compete with the synthetic polymers, and plasticisers such as ethyl phthalyl ethyl glycollate, which are superior in some respects, are now rarely used. 

Plasticizers can be classified according to their chemical nature. The most important classes of plasticizers used in rubber adhesives are phthalates, polymeric plasticizers, and esters. The group phthalate plasticizers constitutes the biggest and most widely used plasticizers. The linear alkyl phthalates impart improved low-temperature performance and have reduced volatility. Most of the polymeric plasticizers are saturated polyesters obtained by reaction of a diol with a dicarboxylic acid. The most common diols are propanediol, 1,3- and 1,4-butanediol, and 1,6-hexanediol. Adipic, phthalic and sebacic acids are common carboxylic acids used in the manufacture of polymeric plasticizers. Some poly-hydroxybutyrates are used in rubber adhesive formulations. Both the molecular weight and the chemical nature determine the performance of the polymeric plasticizers. Increasing the molecular weight reduces the volatility of the plasticizer but reduces the plasticizing efficiency and low-temperature properties. Typical esters used as plasticizers are n-butyl acetate and cellulose acetobutyrate. 

Acetone is a volatile liquid with a distinct sweet odor. It is miscible with water, alcohols, and many hydrocarbons. For this reason, it is a highly desirable solvent for paints, lacquers, and cellulose acetate. Acetone was the 41st highest volume chemical. The 1994 U.S. production was approximately 2.8 billion pounds. 

Plasticised amorphous thermoplastics Certain plastics may be mixed with high-boiling low-volatility liquids to give products of lower T. The most important example occurs with p.v.c. which is often mixed with liquids such as di-iso-octyl phthalate, tritolyl phosphate or other diesters to bring the below room temperature. The resultant plasticised p.v.c. is flexible and to some degree quite rubbery. Other commonly plasticised materials are cellulose acetate and cellulose nitrate. 

AVT Barg BD BDHR BF BOF BOOM BOP BS W BSI BTA Btu/lb BW BWR BX CA CANDUR CDI CFH CFR CHA CHF CHZ Cl CIP CMC CMC CMC COC All-Volatile treatment bar (pressure), gravity blowdown blowdown and heat recovery system blast furnace basic oxygen furnace boiler build, own, operate, maintain balance of plant basic sediment and water British Standards Institution benzotriazole British thermal unit(s) per pound boiler water boiling water reactor base-exchange water softener cellulose acetate Canadian deuterium reactor continuous deionization critical heat flux Code of Federal Regulations cyclohexylamine critical heat-flux carbohydrazide cast iron boiler clean-in-place carboxymethylcellulose (sodium) carboxy-methylcellulose critical miscelle concentration cycle of concentration... 

Topping, D. Illman, R.J. Trimble, R.P. (1985). Volatile fatty acid concentrations in rats fed diets containing gum Arabic and cellulose separately and a mixture. Nutrition Reports International, Vol. 32, (nd) pp. 809-814, ISSN 0029-6635. 

The thermo-gravimetric (TG) and differential thermo-gravimetric (DTG) curves of the gingko nut shell are shown in Fig. 2 where the moisture losses take place up to 200°C followed by the pyrolysis reaction. Then, the major weight loss due to the main degradation occurs at around 360°C. This zone is referred to as the active pyrolysis zone where the evolution of volatile compounds occurs during decomposition of the primary hemi-cellulose and cellulose [5]. 

Additives, such as fire retardants, can have a major effect on pyrolysis, and even trace amounts of ash have been shown to influence pyrolysis (6 ). Generally, fire retardants work by increasing the dehydration reaction rate to form more char and as a direct result give fewer flammable volatile compounds (1,3,7). Several papers have noted that phosphoric acid and its salts decrease the Efl (13,18,22,29), aluminum chloride has little effect (22) on Efl and boric acid increases the Efl (12,18). The reaction order for treated samples has been generally reported as lst-order (12,13,18,29) which is also the most commonly used rate expression for analysis of TGA data of untreated cellulose. 

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