Physics RRL
Rubber; a material our race has come to know and manipulate very well.
We have been using rubber as a base material for containers, for binders, such as rubber bands, for aid in our transportation utilities, like the tires of our cars, for figurines, and children’s toys, for insulators, like the pot holders we find in our kitchen, to the most basic things we find and use in everyday living. We have so many materials made from or with rubber that we often take it for granted.
In the following entries of literature taken from the internet, the researchers will give a brief introduction as to the nature and history of rubber. These entries aim to deepen both the readers’ and the researchers’ understanding of rubber, as well as to recall what they may already know about the said material.
Definition of rubber:
Rubber is an elastic, hydrocarbon polymer that occurs as a milky, colloidal suspension (known as latex) in the sap of several varieties of plants. Rubber can also be produced synthetically. Source: http://www.newworldencyclopedia.org/entry/Rubber
rub·ber (rub′ər)
noun
an elastic substance produced by coagulating and drying the milky sap (latex) of various tropical plants, esp. a tree (Hevea brasiliensis) of the spurge family: now most often produced synthetically or by chemically altering latex to obtain desired characteristics for use in making automobile tires, electrical insulation, molded objects and parts, etc.: in pure form rubber is a white, unsaturated hydrocarbon, having the formula (CH) Source: http://www.yourdictionary.com/rubber
rubber
n.
- A yellowish, amorphous, elastic material obtained from the milky sap or latex of various tropical plants, especially the rubber tree, and vulcanized, pigmented, finished, and modified into products such as electric insulation, elastic bands and belts, tires, and containers. Also called caoutchouc, India rubber.
- Any of numerous synthetic elastic materials of varying chemical composition with properties similar to those of natural rubber.
Source: http://www.answers.com/topic/rubber
The History of rubber:
In its native regions of Central America and South America, rubber has been collected for a long time. The Mesoamerican civilizations used rubber mostly from the plant species known as Castilla elastica. The Ancient Mesoamericans had a ball game using rubber balls, and a few Pre-Columbian rubber balls have been found (always in sites that were flooded under fresh water), the earliest dating to about 1600 B.C.E. According to Bernal Díaz del Castillo, the Spanish conquistadores were so astounded by the vigorous bouncing of the rubber balls of the Aztecs that they wondered if the balls were enchanted by evil spirits. The Maya also made a type of temporary rubber shoe by dipping their feet into a latex mixture.
The first reference to rubber in England appears to be in 1770, when Joseph Priestley observed that a piece of the material was extremely good for rubbing out pencil marks on paper, hence the name "rubber." Around the same time, Edward Nairne began selling cubes of natural rubber from his shop at 20 Cornhill in London. The cubes, meant to be erasers, sold for the astonishingly high price of three shillings per half-inch cube.
The para rubber tree initially grew in South America, where it was the main source of the limited amount of latex rubber consumed during much of the nineteenth century. About one hundred years ago, the Congo Free State in Africa was a significant source of natural rubber latex, mostly gathered by forced labor. The Congo Free State was forged and ruled as a personal colony by the Belgian King Leopold II. Millions of Africans died there, as a result of lust for rubber and rubber profits. After repeated efforts, rubber was successfully cultivated in Southeast Asia, where it is now widely grown.
In the mid-nineteenth century rubber was a novelty material, but it did not find much application in the industrial world. It was used first as erasers, and then as medical devices for connecting tubes and for inhaling medicinal gases. With the discovery that rubber was soluble in ether, it found applications in waterproof coatings, notably for shoes and soon after this, the rubberized Mackintosh coat became very popular.
Nevertheless, most of these applications were in small volumes and the material did not last long. The reason for this lack of serious applications was the fact that the material was not durable, was sticky and often rotted and smelled bad because it remained in its uncured state. Source:http://www.newworldencyclopedia.org/entry/Rubber
Rubber is one of the most important products to come out of the rainforest. Though indigenous rainforest dwellers of South America have been using rubber for generations, it was not until 1839 that rubber had its first practical application in the industrial world. In that year, Charles Goodyear accidentally dropped rubber and sulfur on a hot stovetop, causing it to char like leather yet remain plastic and elastic. Vulcanization, a refined version of this process, transformed the white sap from the bark of the Hevea tree into an essential product for the industrial age.
The opulence of the rubber barons could only be exceeded by their brutality. Wild Hevea trees, like all primary rainforest trees are widely dispersed, an adaptation that protects species from the South American leaf blight which easily spreads through and decimates plantations. Thus to make a profit, barons had to acquire control over huge tracts of land. Most did so by by hiring their own private armies to defend their claims, acquire new land, and capture native laborers. Labor was always a problem so barons got creative. One baron created a stud farm, enslaving 600 Indian women whom he bred like cattle. Other barons like Julio Cesar Arana simply used terror to acquire and hold on to Indian slaves. Indians captured usually submitted because resistance only meant more suffering for the families. Young girls were sold as whores, while young men were bound, blindfolded, and had their genitals blasted off. As the Indians died, production soared: in the 12 years that Arana operated on the Putumayo River in Colombia, the native population fell from over 30,000 to less than 8,000 while he exported over 4000 tons of rubber earning over $75 million. The only thing that stopped the holocaust was the downfall of the Brazilian rubber market.
However the Second World War threatened to shift the rubber wealth. With Japan occupying prime rubber producing areas in Southeast Asia, the US feared it would run out of the vital material. Every tire, hose, seal, valve, and inch of wiring required rubber. The Rubber Development Corporation, the chief overseer of rubber acquisition, sought out other sources including establishing a rubber program that sent intrepid explorers into the Amazon seeking rubber specimen that would be used to produce high yields, superior product, and possibility of resistance against leaf blight. The ultimate goal of the program was to establish rubber plantations close to home. In addition to searching the Amazon and establishing experimental plantations in Latin America, the program came up with some novel plans to produce rubber including planting Dandelions in 41 states. Extensive work on synthetic rubber yielded a product that, in time, economists predicted would replace natural rubber. By 1964 synthetic rubber made up 75% of the market.
However the situation changed drastically with the OPEC oil embargo of 1973 which doubled the price of synthetic rubber and made oil consumers more conscious of their gas mileage. The concern over gas mileage brought an unexpected threat to the synthetic market: the widespread adoption of the radial tire. The radial tire replaced the simple bias tires (which made up 90% of the market only 5 years earlier) and within a few years virtually all cars were rolling on radials. Synthetic rubber did not have the strength for radials; only natural rubber could provide the required sturdiness. By 1993 natural rubber had recaptured 39% of the domestic market. Today nearly 50% of every auto tire and 100% of all aircraft tires are made of natural rubber. 85% of this rubber is imported from Southeast Asia meaning that the US is highly susceptible to disruptions caused by an embargo or worse, the unintentional or intentional introduction of leaf blight into plantations. None of the trees in plantations across Southeast Asia has resistance to blight so "a single act of biological terrorism, the systematic introduction of fungal spores so small as to be readily concealed in a shoe, could wipe out the plantations, shutting down production of natural rubber for at least a decade. It is difficult to think of any other raw material that is as vital and vulnerable."
Source: www.mongabay.com/10rubber.htm
Sources of rubber:
The major commercial source of natural latex used to create rubber is the Para rubber tree, Hevea brasiliensis (Euphorbiaceae). This is largely because it responds to wounding by producing more latex. In 1876, Henry Wickham gathered thousands of seeds of this plant from Brazil, and they were germinated in Kew Gardens, England. The seedlings were then sent to Colombo, Indonesia, Singapore, and British Malaya. Malaya later became the biggest producer of rubber.
Other plants containing latex include figs (Ficus elastica), euphorbias, and the common dandelion. Although these have not been major sources of rubber, Germany attempted to use such sources during World War II when it was cut off from rubber supplies. These attempts were later supplanted by the development of synthetic rubber. Its density is about 920 kilograms/meter3. Source: http://www.newworldencyclopedia.org/entry/Rubber
Properties of rubber:
Rubber exhibits unique physical and chemical properties.
Aside from a few natural product impurities, natural rubber is essentially a polymer of isoprene units, a hydrocarbon diene monomer. Synthetic rubber can be made as a polymer of isoprene or various other monomers. Rubber is believed to have been named by Joseph Priestley, who discovered in 1770 that dried latex rubbed out pencil marks.
The material properties of natural rubber make it an elastomeric and a thermoplastic. Source: http://www.newworldencyclopedia.org/entry/Rubber
Rubber is water repellent and resistant to alkalis and weak acids. Rubber's elasticity, toughness, impermeability, adhesiveness, and electrical resistance make it useful as an adhesive, a coating composition, a fiber, a molding compound, and an electrical insulator. In general, synthetic rubber has the following advantages over natural rubber: better aging and weathering, more resistance to oil, solvents, oxygen, ozone, and certain chemicals, and resilience over a wider temperature range. The advantages of natural rubber are less buildup of heat from flexing and greater resistance to tearing when hot.
Source: www.infoplease.com/ce6/sci/A0860821.html
We can therefore conclude that rubber, both the natural and synthetic type, is polymers as well as raw materials. The main source of rubber, by far, is the Para rubber tree or the Hevea brasiliensis, in scientific terms. The sap of this specific tree, sometimes called latex is collected by factories or locals, and then sold to companies who spread the latex in sheets and press them out as rubber. Rubber has several properties, the most common of which are its elasticity, water repellence, resistance to weak acids and alkalis, its impermeability, and electrical resistance.
The following entries will be focusing on another main proponent of this study; heat.
Heat, for some is the warmth of the sun, that familiar feeling that one gets when a jacket is wrapped around his or her shoulders to ward off the cold. For others, heat is something that is undoubtedly there. The fact that they can feel heat is proof enough for them that it is there; that heat exists. And still, for other minds, those who delve into the various fields of science, heat is a concept; one that revolves around the constant movement of electrons, protons, molecules among others, such that friction is created, and from there, heat is born.
The researchers will now present their research material for the sub-topic, heat.
Definition of Heat:
Heat
n. Physics
a. A form of energy associated with the motion of atoms or molecules and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation.
b. The transfer of energy from one body to another as a result of a difference in temperature or a change in phase.
c. The sensation or perception of such energy as warmth or hotness.
Source: www.answers.com/topic/heat
In physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body.
Source: http://en.wikipedia.org/wiki/Heat