Additives, use

The various additives used to obtain the required properties include anti-knock compounds, anti-oxidants, metal deactivalors, anti-icing additives, etc. 

The base products, TEL and TML, are liquids having boiling points of 205° and 110° respectively. The contents of additives used are usually expressed in grams of lead per liter of fuel in the past they have reached 0.85 g Pb/1. These concentrations are still found in some of the countries of Africa. Elsewhere, when part or all of the motor fuel pool contains lead, the concentrations are much smaller. Thus in Western Europe they no longer exceed 0.15 g Pb/1. 

Furthermore, the formulators having shown plenty of imagination, it would seem illusory to provide an exhaustive list of additives used today. We will mention only the families of additives, protected of course by patents, but well established and widely commercialized. 

An additional useful test is to distil the acid or its sodium salt with soda lime. Heat 0.5 g. of the acid or its sodium salt with 0 2 g. of soda lime in an ignition tube to make certain that there is no explosion. Then grind together 0-5 g. of the acid with 3 g. of soda hme, place the mixture in a Pyrex test-tube and cover it with an equal bulk of soda hme. Fit a wide dehvery tube dipping into an empty test-tube. Clamp the tube near the mouth. Heat the soda lime first and then the mixture gradually to a dull-red heat. Examine the product this may consist of aromatic hydrocarbons or derivatives, e.g., phenol from sahcyUc acid, anisole from anisic acid, toluene from toluic acid, etc. 

Trace metals in sea water are preconcentrated either by coprecipitating with Ee(OH)3 and recovering by dissolving the precipitate or by ion exchange. The concentrations of several trace metals are determined by standard additions using graphite furnace atomic absorption spectrometry. 

The concentration of NO3 in a water sample is determined by a one-point standard addition using an N03 ion-selective electrode. A 25.00-mL sample is placed in a beaker, and a potential of -t0.102 V is measured. A 1.00-mL aliquot of a 200.0 ppm standard solution of N03 is added, after which the potential is found to be -t0.089 V. Report the concentration of N03 in parts per million. 

There are two additional useful parameters which characterize the reaction itself ... 

Table 2. Additives Used in Production of Particleboard as a Percentage of Dry Wood Weight...

Propionic acid, C2H 02, and ammonia [7664-41-7], NH, are additives used to prevent mol ding of feed (5). Bentonite, hemiceUulose extracts, and lignin sulfonate are used to hold feed pellets together. 

Additional uses iaclude (/) filling the enclosed space ia double-pane wiadow units to reduce noise and heat transmission (87,88) (2) acting as a source of power from the reaction with lithium to produce heat (89,90) and (J) pressurizing recreation ball packages such as tennis balls to give improved shelfhfe (91). 

Detergent Additives. Diesel engine deposits ate most troublesome in the fuel dehvery system, ie, the fuel pump and both fuel side and combustion side of the injectors. Small clearances and high pressures mean that even small amounts of deposits have the potential to cause maldistribution and poor atomization in the combustion chamber. The same types of additives used in gasoline ate used in diesel fuel. Low molecular weight amines can also provide some corrosion inhibition as well as some color stabilization. Whereas detergents have been shown to be effective in certain tests, the benefit in widespread use is not fully agreed upon (77). 

Both types of xyloglucans exhibit monolayer sorption onto cellulose (116) and tamarind xyloglucan exhibits maximum specific sorption onto cellulose less than that of coniferous xylan. By inference with other data, this is also less than that of glucomannan and hardwood xylan, but similar to many additives used in the paper industry. 

Metal chlorides which are not readily salted out by hydrochloric acid can require high concentrations of HCl for precipitation. This property is used to recover hydrogen chloride from azeotropic mixtures. A typical example is the calcium chloride [10043-52-4] addition used to breakup the HCl—H2O azeotrope and permit recovery of HCl gas by distillation (see Distillation, azeotropic and extractive). 

Plant investment and maintenance costs are relatively high for a new iodine plant in the United States or in Japan because of the deep weUs required for brine production and disposal as weU as the corrosive nature of the plant streams. The principal materials cost is for chlorine and for sulfur dioxide, although in the United States the additives used for the brines, such as scale inhibitors and bactericides, also have a considerable influence on costs. 

The pH is plant specific, depending on additive used and secondary system materials. Feedwater generally should be equivalent to pH = 9.3 at 25°C for ammonia and carbon steel equipment. 

The chemical industry manufactures a large number of antioxidants (qv) as well as uv stabilizers and their mixtures with other additives used to facilitate resin processing. These companies include American Cyanamid, BASE, Ciba—Geigy, Eastman Chemical, Elf Atochem, Enichem, General Electric, Hoechst—Celanese, Sandoz, and Uniroyal, among others. The combined market for these products in the United States exceeded 900 million in 1994 and will reach 1 billion in the year 2000. 

A hydrolyzed cereal soHd, predominately a hexasaccharide, is used in high pH lime muds for reducing the yield point and gel strength (67). This additive has been used in systems treated with both sodium hydroxide and potassium hydroxide in addition to other additives common to lime muds (68). A second viscosity-reducing additive used in lime muds is a graft copolymer of acryflc acid and calcium flgnosulfonate (69). Both of these materials are used at levels of 6—17 kg/m (2—6 lb /bbl). 

There are occasions where the mud pH must be lowered such as after drilling fresh cement or overtreatment by one of the alkaline materials discussed. Organic acids that have been used for this purpose include acetic acid [64-19-7], citric acid [77-92-9], and oxaHc acid [144-62-7]. These materials are used infrequently. Inorganic additives used to lower pH levels include sodium bicarbonate [144-55-8] and sodium acid pyrophosphate [7758-16-9] (SAPP). Of the two, sodium bicarbonate is used the most by far. 

Additives and Modifications. For plastics uses, nylon is only rarely employed as the pure polymer, and is almost always modified to some extent even if only with the addition of a small amount of lubricant. There has been a dramatic increase in the range and number of combinations of additives used to modify nylons, resulting in a huge expansion in the number of commercial grades available and the uses to which they can be put. It is not unusual to find formulations that contain less than 50% nylon and half a do2en or more additives. 

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