Pencil eraser

Blei-grube, /. lead mine, -gumml, m. lead-pencil eraser (Min.) plumboresinite. bleihsltig, a. containing lead, plumbiferous, Blei-homerz, n. -hornspat, m. phosgenite. 

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. 

Advances in microminiaturization of pumps, battery technology, and transcutaneous energy transmission may make these concepts a reality in the near future. It is now possible to make a pump that is as small as a pencil eraser deliver 5 1/min of blood flow and both axial and centrifugal pumps are being developed with magnetically levitated... 

The atomic nucleus, which contains protons and neutrons, is extremely dense. A piece of atomic nucleus about the size of a pencil eraser would have a mass of 250 million tons ... 

Crush enough iodine crystals to make a pile of powder equal to the volume of a pencil eraser do not grind into a fine powder). 

Each of the twins have read about Joseph Priestley s contribution to the understanding of oxygen, but neither were aware that he also invented the pencil eraser. 

Clean a pre-1982 penny with steel wool or a pencil eraser. 

The growth of the semiconductor industry since the early 1960s has been truly remarkable. Today semiconductors are essential components of nearly all electronic equipment, ranging from radios and television sets to pocket calculators and computers. One of the main advantages of solid-state devices over vacuum-tube electronics is that the former can be made on a single chip of silicon no larger than the cross section of a pencil eraser. Consequently, much more equipment can be packed into a small volume—a point of particular importance in space travel, as well as in hand-held calculators and microprocessors (computers-on-a-chip). 

Remember to take pencils, erasers, a calculator, and a watch. 

Products and Uses Usually in cleansers, scouring agents, fireproofing and insulating compounds, cosmetics for removing rough skin, heavy-duty hand soaps, facial cleansing and acne compounds, tooth polishes, and denture powders. Pencil erasers are composed of synthetic rubber and pumice. (It is the pumice that erases, not the rubber.) Various abrasive purposes. 

Use the web to find out what pencil erasers are made of. Would it be possible to form a new shape of an eraser by melting it and pouring it into a mold ... 

White factice is made by reacting relatively saturated oils, such as castor or rapeseed with liquid sulfur monochloride. The reaction takes place at room temperature, forming a light-colored, more or less crumbly material which sees wide use as lead pencil erasers. 

The easiest way to identify if a polymer is a gel is to place the material under a constant stress and track the deformation with time (Anseth et al.,19% Kavanaugh Ross-Murphy, 1998). This type of test is referred to as a creep test. For a solid polymer (e.g., a hard epwxy or pencil eraser), the deformation will immediately reach a steady state value which is related to the material stiffness (c.f. Figure 4). Likewise, a Newtonian liquid will immediately reach a constant rate of deformation which is proportional to the reciprocal of the liquid s... 

ScufFed-up suede The best tool to erase surface marks is a dry cleaning bar, usually sold with a stiff-bristle brush. The bar is like a pencil eraser use it to remove marks from suede. Then use the brush to bring the nap back up. Finish with a deep-cleaning suede spray. 

Rubber is a naturally occurring polymer, first used as pencil erasers, which was the origin of the English name. It is an addition polymer of isoprene (2-methyl-1,3-butadiene). In forming an addition polymer, a double bond opens up to link each monomer to the chain without forming a second product. Since each molecule of the monomer has two double bonds, there remains one double bond per monomer... 

Factice is used infrequently for special effects in S-B-S and similar thermoplastic elastomers. As an example, pencil erasers formulated with styrenic TPRs contain relatively high loadings of white factice. 

The ASTM procedure requires that two laps of tape be removed and discarded. Next, the piece of tape is apphed to the grid smface and is rubbed finnly with the eraser end of a pencil. The t e must remain on the surface for 90+30 s before removing. The tape is rabbed onto the part using the rubber end of a pencil eraser. The t e type and peel strength must be provided in the report. 

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