Rubber eraser

Radier-fimis, m. etching varnish, -gnind, m. etching grotmd. -gummi, m. (rubber) eraser, -kunst, /. (art of) etching, -messer, n. erasing knife. 

These are special mineral ingredients employed to impart abrasive power to rubber products, used for abrading, grinding or polishing such as rubber erasers and hard or soft rubber grinding wheels such as carborundum. 

Dress shields, vulcanized rubber and rubberized fabric—mitse Druggists sundries, rubber Erasers rubber, or rubber and abrasive combined Fabrics, rubberized... 

Two solid-fuel rockets about 12 feet in diameter and 150 feet long are also attached to the orbiter. Each rocket contains 1.1 million pounds of fuel ammonium perchlorate (NH4CIO4) and powdered aluminum mixed with a binder ("glue"). Because the rockets are so large, they are built in segments and assembled at the launch site as shown above. Each segment is filled with the syrupy propellant, which then solidifies to a consistency much like that of a hard rubber eraser. 

Pressure is defined as a compressive stress, or compressive force per unit area. In a stationary fluid the compressive force per unit area is the same in all directions. In a solid or in a moving fluid the compressive force per unit area at some point is not necessarily the same in ail directions. We can visualize why by considering what happens when we squeeze a rubber eraser between our fingers (see Fig. 1.11). As we squeeze the eraser, it becomes thinner and longer, as shown. If we analyze the stresses in the eraser, we find that the eraser is in compression in the y direction and in tension in the x direction, (This seems strange, bui the eraser has been stretched in the x directions, and its elastic forces are trying to pull it back hence the tension.) The contraction... 

Vinyl erasers are gentler on paper than rubber erasers, and they have some other admirable characteristics as well. For example, white vinyl erasers are good for cleaning ivory. And... 

Besides the major essentials, many of the smaller everyday things often taken for granted are also derived from carbon and its compounds. Consider an ordinary pencil. The lead (actually graphite), the wood, the rubber eraser, and the paint on the surface are all either carbon or carbon compounds. The paper in this book, the ink on its pages, and the glue holding it all together are also made of carbon compounds. 

The hardness of a 2 wt % agarose solid was one third of a conventional rubber eraser and that of a 3 wt % /c-carrageenan containing 0.1 M KCl (M = mol dm ) half of a rubber eraser. It is interesting that the solid surface is su-perhydrophilic the contact angle with water is almost zero degrees. The water inside the solid evaporates much like liquid water, and after standing imder ambient conditions the soUd loses all the water to become a very hard dry solid. 

Modern composite propellants are heterogeneous powders (mixtures) which use a crystallized or finely ground mineral salt as an oxidizer, often ammonium perchlorate, which constitutes between 60 and 90% of the mass of the propellant. The fuel itself is highly pyrophoric aluminum metal powder. The propellant is held together by a polymeric binder, usually polyurethane or polybutadienes. Additional compounds are sometimes included, such as a catalyst to help increase the burning rate, or other agents to make the powder easier to manufacture. The final product is a rubber-like substance with the consistency of a hard rubber eraser. 

Some 500 years ago during Columbuss second voyage to what are now the Americas he and his crew saw children playing with balls made from the latex of trees that grew there Later Joseph Priest ley called this material rubber to describe its ability to erase pencil marks by rubbing and in 1823 Charles Macintosh demonstrated how rubber could be used to make waterproof coats and shoes Shortly there after Michael Faraday determined an empirical for mula of CsHs for rubber It was eventually determined that rubber is a polymer of 2 methyl 1 3 butadiene... 

The bulk properties of a polymer ean often be altered considerably by the incorporation of additives. Probably the most well-known examples of this occur in rubber technology where variations in the choice of additives can produce such widely differing products as tyres, battery boxes, latex foam upholstery, elastic bands and erasers. It is also possible to achieve variations as extensive as this amongst plastics materials, in particular with PVC from which rigid rainwater piping, baby pants, conveyor belting, footballs and domestic insulating flex may all be prepared. 

Tinten-fabrikant, m. ink maker, -farbe, /. ink color, ink dye. -fass, n. inkholder. -fass-feder, /. fountain pen. -fisch, m. cuttlefish, sepia, -fischschwarz, n. sepia (the pigment), -flasche, /. ink bottle, -fleck, m. ink stain, ink spot, -gummi, n. (rubber) ink eraser, -loscher, m. blotter, -pulver, n. ink powder, -stein, m. inkstone. -wein, m. tent (a deep red wine). 

Rubber is a polymer of isoprene (15). Natural rubber is obtained from the bark of the rubber tree as a milky white liquid, which is called latex (Fig. 19.8) and consists of a suspension of rubber particles in water. The rubber itself is a soft white solid that becomes even softer when warm. It is used for pencil erasers and was once used as crepe rubber for the soles of shoes. 

Entrepreneurs in Europe and the United States experimented with mbber hats, coats, erasers, life preservers, and a number of other products. Through the first half of the nineteenth century, however, rubber items were impractical because natural mbber becomes sticky in hot weather and brittle in cold weather. In 1830 the world consumed just 156 tons of mbber, all from Brazil. 

Priestly is said to have given rubber its name because it erased pencil marks. 

Natural rubber can be found as a colloidal emulsion in a white, milky fluid called latex and is widely distributed in the plant kingdom. The Indians called it wood tears. It was not until 1770 that Joseph Priestly suggested the word rubber for the substance, since by rubbing on paper it could be used to erase pencil marks, instead of the previously used bread crumbs. At one time 98% of the world s natural rubber came from a tree, Hevea brasiliensis, native to the Amazon Basin of Brazil which grows to the height of 120 ft. Today most natural rubber is produced on plantations in Malaysia, Indonesia, Singapore, Thailand, and Sri Lanka. Other rubber-bearing plants... 

Elastomeric block polymers of styrene and butadiene or iso-prene and their products of hydrogenation are finding increasing use in a variety of fields.44. Linear and radial block polymers are used extensively in injection molded rubber goods, footwear, pressure sensitive and hot melt adhesives and in mechanical rubber goods such as hose, tubing, cove base, toys, drug sundries, rubber bands, stoppers, erasers, etc. 

Sulfurized olefins (S2C12 plus isobutene) are further reacted with S and Na2S to give products useful as extreme pressure lubricant additives (144,145). The reaction of unsaturated natural oils with sulfur monochloride gives resinous products known as Factice, which are useful as art-gum erasers and rubber additives (146,147). The addition reaction of sulfur monochloride with unsaturated polymers, eg, natural mbber, produces cross-links and thus serves as a means for vulcanizing mbber at moderate temperatures. The photochemical cross-linking of polyethylene has also been reported (148). 

Since the advent of the first rubber lining, research and development work continued and today s rubber technology took a different shape from eraser-to-tyre technology to a more sophisticated high technology discipline known as anticorrosive rubber or... 

Before going further into the various functional characteristics of rubber it is worthwhile to know the meanings of the terms "elastomer" and "polymer" which are synonymous with the term, "rubber" which means a material that when rubbed erases a pencil or pen mark. Michael L. Berins [2] describes the above terms in the following manner. 

Use Erasers, rubber goods (bath spray tubing, etc.) to give soft hand. ... 

---