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=~The Effects of Temperature on the Strength of Rubber Bands~=

LIT. REVIEW
Rubber is included in our everyday life. It's used for tires, shoes, balloons, and many other things. Rubber goes back in history to the early 1700s. In the Caribbean Islands, locals were the first ones to use rubber. Many things make and effect rubber.

When Christopher Columbus came to find new treasures and land, he was the first to bring rubber back to Europe. It was traded with the American colonies and was introduced to the western world by Charles de la Condomien in 1736. In 1839, Charles Goodyear discovers that heating the process of Vulcanization stabilizes and strengthens the rubber's properties. The process of Vulcanization let the rubber stretch farther. In 1770, Joseph Priestley, a chemist, was the first person to use rubber to erase lead (pencil) marks. ( Thomas, R. & Sydenham, S)

Rubber has a short process before it becomes a product to sell. Rubber comes from a Rubber tree grown in Asia. The three largest rubber- making countries are Thailand, Indonesia, and Malaysia. The life period of a Rubber tree is 32 years, 7 years is to grow and 25 years is to produce. Every season, the rubber latex would be drawn out from the Rubber tree. People would drain the liquid out of the tree. It takes about 6 hours to have the liquid to come out. In 6 hours, the tree can provide a gallon and can be taken the next day. Rubbertrees can be extracted every 16- 24 hours. To tap a tree the collector makes a small, diagonal cut to remove a very thin part of the bark. The Mesoamericans, people who are from Mexico and Central America, would dry the collected latex and make balls, shoes, and other things. They dip their feet in the latex and let it dry. After several dips and dryings, they peel a shoe from their own feet. Then, they smoke their new rubber shoes to harden them. The Mesoamericans can also waterproof fabrics by coating them with the rubber latex and allowing it to dry. This process is used to make rubber products until the 1800s. ( Freudenrich, Craig C)

Rubber is the perfect example of a natural polymer. A natural polymer is made from just carbon and hydrogen. Natural polymers include the RNA and DNA that are important in genes and life processes. Messenger RNA is what makes possible proteins, peptides, and enzymes. Enzymes help do the chemistry inside living organisms and make up some of the structural parts of skin, hair, and other things. Rubber bands have a natural elasticity which means they can stretch when pulled. When the pulling force is removed, the elastic polymers in the rubber snap back to its original shape. Polymers with elastic properties are called elastomer. Elastomers basically act like springs because of molecular chains. ( McNeil, Anne J)

Elasticity is the ability to reshape after being deformed by force. If stressed is added to a solid, it reaches its elastic limit and will not return to its original shape. Stress is similar to strain. Strain measures how much a dimension of a solid is changed under stress. Objects with a high elastic modulus, like steel, has a stronger resistance to stress than to an object with low elasticity, like rubber. Elastic modulus is the measure of stiffness. The equation for elasticity of a rubber band is (delta L) = (FA)/ (EA), when (delta L) is length change, F is force, L is length, E is elastic modulus, and A is cross- sectional area. ( E., Andy )

Everything in the world is made up of molecules. Molecules are tiny particles which are made up of several different atoms. In solid, they fit together into one shape; but in liquids, they move around freely. Molecules are, however, affected by temperature. They move faster with heat and slower with less warmth. There aren’t a lot of ways individual molecules can move and arrange themselves when a rubber band is stretched, unlike when it is not pulled. They have to straight. The links between the molecular chains are called cross links. When too much force is put on the cross links, they’ll break and the rubber band snaps. Entropy, a measure of numbers of specific ways in which a system may be arranged, is higher when there are more ways to shape molecules. When a rubber band is pulled, entropy says that the band wants to contract. ( Shakhashiri, Bassam Z)

Heat is everywhere. The sun, earth, electricity, friction, and chemical reactions are some types of heat. Heat is the most important type of energy even if they cannot be seen. Atoms and molecules, which are always moving, make up everything. The motion gives an object internal energy. How rapidly atoms or molecules move depends on the level of an object’s internal energy. If an object has a high internal energy, it’s hot; but if it’s low, it is cold. ( Shakhashiri, Bassam Z)

Bibliography:
E., Andy. "Science Project." // Science Project //. N.p., 2001. Web. 24 Sept. 2013. <[]>.
 * This is a valid source because the boy did the experiment before and found useful resources.

Freudenrich, Craig C. "How Rubber Works." // HowStuffWorks //. N.p., n.d. Web. 25 Sept. 2013. <[]>.
 * Craig C. Freudenrich, Ph.D. is a freelance science writer and former senior editor at HowStuffWorks. He earned a B.A. in biology from West Virginia University and a Ph.D. in physiology from the University of Pittsburgh School of Medicine before completing eight years of postdoctoral research at Duke University Medical Center.

McNeil, Anne J. "ASK! Options." //CCMR//. N.p., 4 Jan. 2006. Web. 25 Sept. 2013. <[]>.
 * This is a valid site because it was made by Scientist Anne J. McNeil, Post-doctoral Researcher and MIT, Department of Chemistry. Her research area is Organic and Polymer Chemistry

Shakhashiri, Bassam Z. "Rubber Bands and Heat." //Rubber Bands and Heat//. N.p., n.d. Web. 24 Sept. 2013. <[]>.
 * This is a valid source because it comes from the CHEMICAL DEMONSTRATIONS: A Handbook for Teachers of Chemistry, Volume 1, by Bassam Z. Shakhashiri, The University of Wisconsin Press, 2537 Daniels Street, Madison, Wisconsin 53704.

Thomas, R. & Sydenham, S. "Rubber." //Rubber//. N.p., Aug. 2013. Web. 25 Sept. 2013. <[]>
 * They based their info HowStuffWorks which was created by Craig C. Freudenrich, Ph.D.