Dispersion deterioration

Dispersants are used so infrequently in some locations that stockpiles are sometimes in place for as long as 20 years before use. In Great Britain, the government studied the aging of dispersants by testing effectiveness [JJO]. The laboratory performed both long-term tests and short-term accelerated tests in various containers and at 20 and 30 °C. The tests did not show dispersant deterioration as indicated by the effectiveness values. 

Wool—Polyester Fibers. The 45/55 wool—polyester blend is the most common fiber combination in the worsted industry. Strength and exceUent dimensional stabiHty of the polyester fiber enable the creation of lightweight wear fabrics not obtainable before. Economy has modified the fiber ratio and 30/70 and 20/80 wool—polyester blends are as common as the classical 45/55 blend. Disperse dyes for polyester and acid or neutral premetaUized dyes for wool are employed in a one-bath process. Should cationic dyes be used for the wool portion, a one-bath procedure can only be employed for light to medium shades, whereas dark shades require a one-bath two-step process. Wool blends should not be dyed above 105°C in order to avoid deterioration of the fiber quaHty. 

A mixture of monolauryl phosphate sodium salt and triethylamine in H20 was treated with glycidol at 80°C for 8 h to give 98% lauryl 2,3-dihydro-xypropyl phosphate sodium salt [304]. Dyeing aids for polyester fibers exist of triethanolamine salts of ethoxylated phenol-styrene adduct phosphate esters [294], Fatty ethanolamide phosphate surfactant are obtained from the reaction of fatty alcohols and fatty ethanolamides with phosphorus pentoxide and neutralization of the product [295]. A double bond in the alkyl group of phosphoric acid esters alter the properties of the molecule. Diethylethanolamine salt of oleyl phosphate is effectively used as a dispersant for antimony oxide in a mixture of xylene-type solvent and water. The composition is useful as an additive for preventing functional deterioration of fluid catalytic cracking catalysts for heavy petroleum fractions. When it was allowed to stand at room temperature for 1 month it shows almost no precipitation [241]. 

The highly dispersible calix[4]arene neutral carriers can also improve the durability for neutral-carrier-type ion sensors. Time-course changes in both sensitivity (slope for Na+ calibration graph) and selectivity (selectivity coefficient for Na" " with respect to K+) were followed in the Na -ISFETs based on ion-sensing membranes of silicone rubber-(l), plasticized PVC-(l), and plasticized PVC-(2) (Fig. 2). Deterioration proceeded quite quickly in the Na -ISFETs of plasticized PVC-(2) both the Na+ sensitivity and selectivity... 

Quaternary alkylammonium salts are generally water-soluble surfactants. The sol-gel-derived anion-sensing membranes encapsulating a quaternary alkylammonium salt, especially with high contents, are easy to deteriorate due to the exudation of the cationic site from the membrane to aqueous sample phases. Moreover, another issue concerning the dispersibility of ammonium salts in sol-gel-derived membranes may happen when high... 

Since disperse dye powders supplied to the dyer have been treated already to render them essentially non-dusting, dustiness problems are mainly of concern during dye manufacture [92]. Nevertheless, some dyes remain inadequately treated, or after an initially adequate treatment they may deteriorate during storage, thus giving rise to hazards in handling associated with excessive dustiness. Methods of assessing dustiness have been reviewed [92]. 

It should be noted that some problems may arise in the techniques or devices for producing monodisperse or near-monodis-perse sprays. One of the problems is droplet coalescence. Initially uniform droplets may coalesce rapidly to create doublets or triplets, particularly in a dense and turbulent spray, deteriorating the monodispersity of the droplets. This problem may be lessened by using appropriate dispersion air around the spray.[88] Another problem is non-spherical droplet shapes that make estimations of monodispersity difficult. 

Since the Initial work of White (IQ), the Bell System and other major semiconductor users have extensively used silicones In the protection of numerous thin-film and thlck-fllm devices (24.25). The materials primarily have been condensation-cure silicones In xylene dispersion. The performance of encapsulated semiconductors used within the Bell System Is well documented (26). and studies continually In process support the use of silicones for the prevention of electronic component deterioration under conditions similar to the In-vlvo environment. 

Acetylenic compounds may undergo deterioration during storage. Decomposition of the residue which remains after redisrillation can then sometimes lead to an explosion. A method to minimize the danger of vigorous decomposition is to add an amount of paraffin oil prior to distillation. The residue then remains as an emulsion or dispersion in the oil after the compound has been distilled off. It is further advisable to carry out the distillation in vacuo even when the compound itself has a reasonable thermal stability. The apparatus depicted in fig. 14 can be used for this purpose. 

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