Crude rubber

Howard himself anticipated a refusal.. . . Howard inquired whether in the present circumstances, we would be able to transmit to the United States experiences for the production of buna. He himself considered this unlikely since, in the event of war, the United States would be dependent upon the importation of crude rubber.. .. In any event, he has not conditioned the readjustment of Jasco upon our furnishing experience for buna. 

The characteristic property of elastomers is their rubber-elastic behavior. Their softening temperature lies below room temperature. In the unvulcanized state, i.e. without crosslinking of the molecular chains, elastomers are plastic and thermo-formable, but in the vulcanized state—within a certain temperature range — they deform elastically. Vulcanization converts natural rubber into the elastic state. A large number of synthetic rubber types and elastomers are known and available on the market. They have a number of specially improved properties over crude rubber, some of them having substantially improved elasticity, heat, low-temperature, weathering and oxidation resistance, wear resistance, resistance to different chemicals, oils etc. 

Uses Manufacture of nylon solvent for cellulose ethers, fats, oils, waxes, resins, bitumens, crude rubber paint and varnish removers extracting essential oils glass substitutes solid fuels fungicides gasoline and coal tar component organic synthesis. 

Uses Solvent for cellulose acetate, crude rubber, natural resins, nitrocellulose, vinyl resins, waxes, fats, oils, shellac, rubber, DDT, and other pesticides preparation of adipic acid and caprolactum additive in wood stains, paint, PVC paints, lacquers (to prevent blushing or improve flow), and varnish removers degreasing of metals spot remover lube oil additive in PVC adhesives to control evaporation rate leveling agent in dyeing and delustering silk. 

Friedler s Incendiary Composition consisted of a mixture of crude rubber and metallic sodium or potassium, which was intended to burn while floating on the surface of water Ref Daniel (1902), 310... 

It has been known that a very small quantity of DNsoPMT added to crude rubber rendered it, after heating, more pliable and spongy. It is probable that on the strength of this knowledge, the US Agency of International Development shipped in 1966 50... 

THERMOPLASTIC. A high polymer that softens when exposed to heat and returns to its original condition when cooled to room temperature. Natural substances that exhibit this behavior are crude rubber and a number of waxes however, the term is usually applied to synthetics such as polyvinyl chloride, nylons, fluorocarbons, linear polyethylene, polyurethane prepolymer, polystyrene, polypropylene, and cellulosic and acrylic resins. See also Plastics. 

Properties of Chlorate Explosives. In general, expls based on chlorates are very powerful and brisant, but are very sensitive to friction and impact. Coating of particles of chlorates with substances such as castor oil, rosin, paraffin, tar, aromatic nitrocompds, crude rubber, vaselin, pertoleum, plastic materials, diminish considerably the sensitiveness but not sufficiently to make these expls suitable for loading artillery shells(See CHEDDITES) The chlorate expls are more sensitive than those contg perchlorates, and expls contg Na chlorate are more sensitive than those with K chlorate. Expls contg K or Na chlorate should not be mixed with Amm salts because, in this case, double decomp takes place with the formation of Amm chlorate which can explode spontaneously. It also is advisable not to use either PA or.TNCrs in chlorate expls, because such mixts are very sensitive(Ref 7,p 383). These precautions were not always followed... 

Each mixt was evapd in vacuo at low temp to the point of formation of crysts- After decanting the mother liquor, the crysts were pulverized coated with a soln of crude rubber (or other gummy subst) in petroleum naphtha and then either pressed or grained. Mixture No 1 was suitable for miliatry purposes and was recommended for loading torpedoes Ref Daniel (1902), 181-82... 

If the degree of cross-linking is not very great, as in crude rubber, viscous flow can occur, the polymer chains moving permanently into new equilibrium positions. Excessive cross-linking, on the other hand, restricts changes in the chain configurations and the rubber becomes hard and difficult to deform. 

In manufacture, the abrasive grain is mixed with crude rubber, sulfur, and other ingredients for curing, then passed through calender rolls to produce a sheet of desired thickness. The wheels are stamped from this sheet and heated under pressure to vulcanize the rubber. 

Crude rubber, called latex, is collected from the tree as an aqueous dispersion that is washed, dried, and coagulated by warming in air. The resultant polymer has chains that average about 5000 monomer units in length and have molecular weights of 200,000-500,000. This crude coagulate is too soft and tacky to be useful until it is hardened by heating with elemental sulfur, a process called vulcanization. By mechanisms... 

Use Solvent for nitrocellulose, cellulose ether, bitumens, metallic soaps, basic dyes, blown oils, crude rubber, many natural and synthetic resins and gums, lacquers. 

Veneer, plywood Rosin, turpentine Gases not petroleum Cottonseed oil Linseed oil Vegetable oils, n.o.s. Rubber, crude Rubber goods, n.o.s. Chemicals, n.o.s. 

India rubber Natural rubber crude rubber obtained from latex. 

Crude rubber is primarily hydrocarbon in nature. In 1826 English chemist Michael Earaday (1791-1867) analyzed natural rubber and found it to have the empirical (simplest) formula C5H8, along with 2 to 4 percent protein and 1 to 4 percent acetone-soluble materials (resins, fatty acids, and sterols). In 1860 English chemist Charles Hanson Greville Williams (1829-1910) confirmed Earaday s analysis and in 1862 distilled natural rubber to obtain the pure monomer, which he named isoprene. He determined isoprene s vapor density and molecular formula, and he showed that it polymerizes to a rubbery product—an observation that led to the notion that rubber is a linear polymer of isoprene, proposed in 1910 by English chemist Samuel Shrowder Pickles (1878-1962). 

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