Plasticization of sulfur

Sulfur dioxide [7446-09-5] is formed as a result of sulfur oxidation, and hydrogen chloride is formed when chlorides from plastics compete with oxygen as an oxidant for hydrogen. Typically the sulfur is considered to react completely to form SO2, and the chlorine is treated as the preferred oxidant for hydrogen. In practice, however, significant fractions of sulfur do not oxidi2e completely, and at high temperatures some of the chlorine atoms may not form HCl. 

A polyester-type fluorescent resin matrix (22) is made by heating trimellitic anhydride, propylene glycol, and phthaUc anhydride with catalytic amounts of sulfuric acid. Addition of Rhodamine BDC gives a bright bluish red fluorescent pigment soluble in DME and methanol. It has a softening point of 118°C. Exceptional heat resistance and color brilliance are claimed for products of this type, which are useful for coloring plastics. 

The remaining tailings left over from the clay fractionation step is either flocculated with alum, high molecular weight polymers, or a weak (pH 3.0) solution of sulfuric acid, and stored in settling ponds as waste, or may be filtered and sold to the brick industry as a coating material. It also may be dried and sold as a filler in plastics and textured paint (qv). 

Plastics and Other Synthetic Products. Sulfur is used in the production of a wide range of synthetics, including cellulose acetate, cellophane, rayon, viscose products, fibers, and textiles. These uses may account for 2% of sulfur demand in developed countries. Sulfur intermediates for these manufacturing processes are equally divided between carbon disulfide and sulfuric acid. 

Cellulose acetate [9004-35-7], prepared by reaction of cellulose with acetic anhydride, acetic acid, and sulfuric acid, is spun into acetate rayon fibers by dissolving it in acetone and spinning the solution into a column of warm air that evaporates the acetone. Cellulose acetate is also shaped into a variety of plastic products, and its solutions are used as coating dopes. Cellulose acetate butyrate [9004-36-8], made from cellulose, acetic anhydride, and butyric anhydride in the presence of sulfuric acid, is a shock-resistant plastic. 

CN is the oldest and most important inorganic ester of cellulose. It is a white, ododess, and tasteless substance. It has found uses in plastics, lacquers, and explosives. CN is manufactured by treating cellulose with nitric acid in the presence of sulfuric acid and water. The amount of water determines the DS attained (11,48,49). 

Cyclopentadiene oligomers have been formed by vapor deposition of CPD on kaolin to afford a sorbant for removal of oil from water (71). They are also employed as coatings for controlling release rates of fertilizers (72). Thermal addition of sulfur to a mixture of DCPD and CPD oligomers has led to a number of beneficial appHcations such as waste water oil adsorbant powdery foams (73), plasticized backing for carpets and artificial turfs (74), and in modified sulfur cements for encapsulating low-level radioactive wastes (75). 

A lead-acid battery consists of electrolytic cells, each containing an anode of porous lead, a cathode of primarily lead peroxide (PbO,), and electrodes of metallic lead. The anode and cathode are separated by nonsulfuric acid and water. 

Sulfur mortars (mixture of sulfur and inert fillers with small amounts of organic plasticizers) are used for shrinkage mitigation and for eliminating thermal shocks for temperatures up to 80°C. These mortars have poor resistance to alkalis and nonpolar organic solvents. 

Vulcanisation is the term used for the process in which the rubber molecules are lightly crosslinked in order to reduce plasticity and develop elasticity. It was originally applied to the use of sulfur for this purpose, but is now used for any similar process of cross-linking. Sulfur, though, remains the substance most widely used for this purpose. 

About 3 billion kilograms of hydrochloric acid are produced each year, mostly as a by-product of the plastics industry. The largest single use of hydrochloric acid is the pickling of steel. The pickling process removes iron(III) oxide (FC2 O3, rust) from the surface of the metal. About a third of all hydrochloric acid is used to produce other chemicals, mostly ionic compounds. Other strong acids have specialized applications in indushy and research laboratories, but none approaches the importance of sulfuric, nitric, and hydrochloric acids. 

Ic. Cross-Linking of Polymer Chains.—Formation of chemical bonds between linear polymer molecules, commonly referred to as cross-linking, also may lead to the formation of infinite networks. Vulcanization of rubber is the most prominent example of a process of this sort. Through the action of sulfur, accelerators, and other ingredients present in the vulcanization recipe, sulfide cross-linkages are created by a mechanism not fully understood (see Chap. XI). Vulcanized rubbers, being typical network structures, are insoluble in all solvents which do not disrupt the chemical structure, and they do not undergo appreciable plastic, or viscous, flow. 

Chlorination of natural rubber, involving both addition and substitution (with some cyclization), yields a product with improved chemical and corrosion resistance. Chlorination of polyethylene in the presence of sulfur dioxide results in substituting both chloride and sulfonyl chloride groups into the polymer. A commercially useful material is one which contains about 12 chlorides and one sulfonyl chloride per 40-45 repeating units. This extensive substitution converts the polyethylene, a plastic, into an elastomer by destroying crystallinity. 

As previously mentioned, past studies used non-filtered air with unknown concentrations of trace gases at unknown relative humidities. Also, many of the studies used plastic aging chambers that may have introduced volatile monomers into the air. These unknown factors are important to determine in order to fully understand the nature of the ultrafine particle mode. According to the classical thermodynamic theory of ion cluster formation (Coghlan and Scott, 1983), the relative humidity and trace gases will affect the existence of condensation nuclei. Megaw and Wiffen (1961) observed an increase in nuclei formation with the presence of sulfur dioxide. 

The usual form of sulfur is known as the rhombic form, which is stable at temperatures up to about 105 °C. Above that temperature, the monoclinic structure is stable. A plastic form of sulfur can be obtained by pouring liquid sulfur into water to cool it quickly, but on standing it is converted to the rhombic form. On a molecular level, the element exists as S8 rings that have the structure... 

Some industrially important catalytic reactions (with their catalysts) which are the bases for such large-scale operations as the production of sulfuric acid, agricultural fertilizers, plastics, and fuels are ... 

Fiber-bed scrubbers are used to control aerosol emissions from chemical, plastics, asphalt, sulfuric acid, and surface coating industries. They are also used to control lubricant mist emission from rotating machinery and mists from storage tanks. Fiber-bed scrubbers are also applied downstream of other control devices to eliminate a visible plume. Despite their potential for high collection efficiency, fiber-bed scrubbers have had only limited commercial acceptance for dust collection because of their tendency to become plugged. 

Formals and acetals prepared from the reaction of polynitroaliphatic alcohols with formaldehyde and acetaldehyde have found use as explosive plastisizers for nitrocellulose and in plastic bonded explosives (PBXs). Formals of polynitroaliphatic alcohols are commonly prepared via reaction with trioxane or paraformaldehyde in the presence of sulfuric acid as a condensing agent. Bis(2,2-dinitropropyl)formal (175) is prepared from the reaction of trioxane with 2,2-dinitropropanol (25). The reaction of 2,2,2-trinitroethanol (159) and 2,2-dinitro-l,3-propanediol (19) with formaldehyde in the presence of sulfu-... 

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