Plastic mass

F. H. Norton, Forming Plastic Masses, Fine Ceramics Technology and Applications, Robert E. Krieger Publishing, Huntington, NY, 1978, Chapt. 10. 

Objectives of Gas Dispersion The dispersion of gas as bubbles in a liquid or in a plastic mass is effected for one of the following purposes (1) gas-liquid contacting (to promote absorption or stripping,... 

Of these materials zein, the maize protein, has been used for plastics on a small scale. It can be cross-linked by formaldehyde but curing times are very long. Complicated bleaching processes have led to the production of almost colourless samples in the laboratory but the process cannot readily be extended to large-scale operation. The cured product has a greater water resistance than casein. Proteins from soya bean, castor bean and blood have also been converted into plastic masses but each have the attendant dark colour. 

The ebonite compound before cure is a rather soft plastic mass which may be extruded, calendered and moulded on the simple equipment of the type that has been in use in the rubber industry for the last century. In the case of extruded and calendered products vulcanisation is carried out in an air or steam pan. There has been a progressive reduction in the cure times for ebonite mixes over the years from 4-5 hours down to 7-8 minutes. This has been brought about by considerable dilution of the reactive rubber and sulphur by inert fillers, by use of accelerators and an increase in cure temperatures up to 170-180°C. The valuable effect of ebonite dust in reducing the exotherm is shown graphically in Figure 30.3. 

In judging whether or not petroleum ether should be added, the following rule should be observed Add enough petroleum ether to soften the cineol arsenate, so as to obtain a plastic mass the quantity necessary never exceeds 5 c.c., and decreases vsith oils containing less than 80 per cent, of cineol. The object of adding petroleum ether is merely to soften the hard mass and to aid in the separation of non-cineol constituents of the oil a large excess of petroleum ether will decompose the compound. 

Modellier-holz, n. (wooden) modeling tool, -masse, /. modeling composition (as clay), plastic mass, -ton, 7n. modding clay, -wachs, 71. modeling wax. 

Most practical cements contain Mg " which is less strongly bound to the polyacrylate than Zn (Gregor, Luttinger Loebl, 1955a). Magnesium oxide forms a paste with PAA which sets to a plastic mass this is not hydrolytically stable, for when placed in water it swells and softens (Hornsby, 1977 Smith, 1982a). Moreover, if ZnO powder contains more than 10% MgO, the resultant cement deteriorates under oral conditions. 

While some formed hard, rigid cements that were stable in water, others yielded rubbery or plastic masses that were hydrolytically unstable. Minerals with cement-forming capability were found in the following classes ... 

A great potential for new compounds is provided by structures with two carbon and two silicon atoms around the central silicon. These polysilanes with organic groups lead to silicon-carbide ceramics. A wide field of application would be opened up if one could make a polysilane as a plastic mass which could be extruded and modeled and if after pyrolysis silicon-carbide is formed without a strong contraction (this means a high ceramic yield). Polysilane fibers are only one product in a range of many... 

Halsey and Savage Explosives. Several smokeless powders, containing Ammonium Picrate, were patented in the US in 1896. They were prepd by adding finely pulverized Ammonium Picrate to an aqueous solution of potassium dichromate in such a manner as to form a plastic mass and then slowly adding a coned aqueous solution of potassium permanganate. 

Kinetite (Kinetit or Kinenite-Swiss). One of the earliest gelatinous (plastic) expls which contd no NG. It was patented in 1884 by Petry and Fallenstein and was used extensively at the end of the last century in Ger and other European countries. It was prepd by gelatinizing Nitrobenzene or Nitrotoluene with Collodion Cotton, and impregnating this plastic mass with sulfur, K chlorate and other ingredients. Sulfur was later replaced by Sb penta-sulfide. Its compn was NB 16.0 to 21.0, Collodion Cotton 0.75 to 1.0, K chlorate 82.5 to 75.0, Sb2Ss and/or K nitrate 3.0 to 1.0%. The function of the Sb pentasulfide was to render the explosion more regular and more complete... 

Procedure Fill a %x4 incb test tube to a depth of 1 inch with the specimen ground to pass a No 16 mesh screen. Submerge the tube to a depth of 2 inches in an oil bath previously heated to 120°, place a thermometer in the EtCell and increase the bath temp at the rate of 2°C per min, while stirring the specimen by means of thermometer. At a temp approx 25° below fusion point the particles soften and tend to cohere, making it difficult to stir. Continue beating and working the mass until it fuses and becomes plastic. Read the "thermoplastic point" as the temp at which the plastic mass can be repeatedly drawn into thread by pulling the thermometer from the mass. Duplicate detns should check within 3°C... 

Other contaminants that can originate from plastic containers are the additives necessary to turn the raw polymer into adequate containers. While PE may be used without any additive, the other plastics are virtually useless alone but are converted into highly serviceable products by combining them with other substances or materials. The additives most commonly found in plastics used for pharmaceutical products are antioxidants, heat stabilizers, lubricants, plasticizers, fillers, and colorants. These additives can be in liquid, solid, or fine particle forms and are used in amounts varying from less than 1% to more than 50% of the plastic mass. The additives necessary for each of the selected types of polymers are described in Table 23. 

HEAT THE THICKENED SULFUR FURTHER UNTIL IT FLOWS FREELY AGAIN. THEN POUR THE DARK FLUID INTO COLD WATER. IT TURNS INTO A PLASTIC MASS. IN A FEW DAYS THIS AGAIN BECOMES YELLOW SULFUR. 

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