21 days Essay Example | Topics and Well Written Essays - 1000 words

21 days - Essay Example What to do? Today started well after two of my assignments received maximum points. However, my mentor put a dampener on my spirits by telling me I was falling behind my schoolwork. At times, I think I do not need a mentor, but she helped me a lot last semester. I also reconnected with an old friend Chris on Facebook, which was fun. Today I feel in need of inspiration, and I decide not to visit my mentor for two weeks. I attend a poetry club meeting, which was impressive, and it went some way in inspiring me. I also registered as a member of the drama club as I feel I need something to inspire me at school. Finally, Chris wanted financial help, and I feel I can trust him. Today my friends and I went bowling, and I did well. I bowled a 150, 166, and 160. However, I was still feeling downcast, especially during class. Another of my assignments came back with a C. I revised it and resubmitted it in the hope of getting a better score. I attended my first drama club meeting and felt lost, as there was such camaraderie among the other members. I forgot to write another assignment last night and had to do it in class today. After handing it in, I tried to write some poetry in class to lighten my spirits. On my way from class, I came across some lottery tickets, which had a jackpot of 140 million. Although, I purchased three tickets, I did not win, and neither did anyone else at that time so, I did not feel too downhearted. My mentor called me today and asked me to see her, which I did. I was not aware I was supposed to see her once every two days. I also lent my friend some $300, which I pray is not a mistake as he sounded desperate. The poetry is not improving my spirits, and I decided to try the drama club instead. Today, I managed to make two friends there and got to know how they interact. It was fun. Today was a very busy day with a surprise CAT test. One of my classmates was caught copying my work and

Economy Essay Example | Topics and Well Written Essays - 1000 words - 2

Economy - Essay Example Principles of Political Economy and Taxation was published in 1817. In this publication, Ricardo developed law of rent as well as the labor theory of money (Gonner, 2013). The theory of comparative advantage, as developed by Ricardo, tries to explain the benefit of engaging in international trade. The theory was initially discussed by Adam Smith in the Wealth of Nations. The theory was, however, clearly developed by Ricardo in the book On the principles of Political Economy and Taxation. In the development of the comparative advantage theory, Ricardo observed that if two countries with a capability of producing two products participate in free trade, each of the two countries will increase productivity by exporting the commodity that it has a comparative advantage in production. The country would then import the other commodity. In this theory, Ricardo implies that comparative advantage, and not absolute advantage, is responsible for international trade (Gonner, 2013). The example used by Ricardo to explain comparative advantage involved England and Portugal. In this example, the two countries produce cloth and wine. However, Portugal is more efficient in the production of the two commodities compared to England. England needs 100 hours to produce a unit of cloth and 120 hours to produce a unit of wine. Portugal on the other hand requires 90 hours to produce unit of cloth and 80 hours to produce a unit of wine. In this case, England requires 100 hours to produce cloth, which can instead produce an incomplete unit of wine. Portugal can produce a unit of cloth with few hours compared to England. However, Portugal must forego the production of more units of wine in order to produce a single unit of cloth. Although Portugal has an absolute advantage in the production of cloth, England has a comparative advantage in the production of cloth. In this example, England has a comparative advantage in the

History and Properties of Rubber

History and Properties of Rubber History of Rubber Rubber was first discovered by the Indians living in Central and South America at around 1000 CE. The native people of the Americas used latex from the rubber trees (which they called it the cahuchu tree) and learned how to make waterproof clothes and footwears.1 They also used the latex to make bouncing balls for ball games.1 In 1736, a French explorer named Charles Marie de La Condamine travelled to Ecuador and discovered the Hevea tree (which is known as the rubber tree), he was the first European to have discovered rubber. He sent samples of this rubber to the French Academy of Sciences, this prompted their interest of rubber.2 Figure 1: Latex liquid collected from the Hevea rubber tree 3 In 1770, English engineer named Edward Nairne created several rubber cubes and discovered that they had erasing properties. This meant that they can be able to erase pencil marks, this was later confirmed by English scientist named Joseph Priestley.4 In 1768, a French Chemist named Pierre Macquer studied the properties of the rubber found in South America. He found that when rubber is dissolved in ether, flexible tubes can be produced 5, this has led to rubber being an important material to many everyday applications. In 1791, a British shoemaker named Samuel Peal developed a method for waterproofing cloth, this was done by mixing turpentine (which is an oiled that is attained by the distillation of resin from pine trees) with rubber.6 In 1818, a Scottish surgeon named James Syme manufactured raincoats from waterproof cloth made from rubber.7 This was then later developed by Scottish chemist named Charles Macintosh. In 1823, he developed a method of making better waterproof raincoats by dissolving rubber with naphtha (which is an oil attained by the distillation of coal tar) and then placing it with another cloth (in order to improve the thickness of the coat). The waterproof coat became known as the Mackintosh coat.8 Figure 2: The Mackintosh Coat 9 In 1832, the first rubber factory was built, it was known as the Rosburg factory. Regrettably, when the rubber products made from the factory were left in the cold, it made them brittle, and when they were left in the sun the rubber melted, leaving customers to be discouraged.8 For many years, scientists have tried to develop new methods of increasing the strength of rubbers without being successful. However, in 1839, an American chemist named Charles Goodyear had accidently discovered a new way of making rubbers more durable. What he done was he accidentally dropped some mixture of natural rubber and sulphur on a hot stove, this has led to the vulcanization of the rubber. 8 In 1845, a Scottish inventor named Robert William Thompson invented the pneumatic tyre, this consisted of an inner belt made from natural rubber that was inflated with air, this was a major development to the motor industry because heavy steam engines could be able to travel on the roads without damaging the surface, this was further developed in 1869 where solid and hollow rubber were used to make the tyres. In the 1850s, rubber toys were being produced. 8 In 1876, an English explorer named Henry Wickham smuggled several seeds from the Hevea brasiliensis (which is the rubber tree found in Brazil) and took it to England. The English exported these seeds around the world, this has led to the increase in the supply of natural rubber around the world. 10 In 1883, an American chemist named George Oenslager developed a new method of accelerating the vulcanization of natural rubber with sulphur.7 He converted aniline into thiocarbanilide because it was easier to handle. From several experiments he conducted, he found out that thiocarbanilide was a good rubber accelerator for the vulcanization process. He was the first person to use carbon black as a filler for the rubber because it increased the strength of the rubber. 11 In 1909, a German scientist named Fritz Hofmann and his fellow scientists produced the first synthetic rubber known as methyl isoprene however the problem with this rubber is that it was expensive to make.12 In 1930, an American scientist named Wallace Carothers and his team produced a compound called chloropropene which then polymerised to form a solid which had a rubbery texture. The team had found out that the properties of this new polymer was similar to that of natural rubber. This polymer was named as Neoprene and was the first commercially successful synthetic rubber.13 Also in the 1930s, a German chemist named Walter bock had developed a new synthetic rubber which had better properties than that of natural rubber. He first tried to copolymerise dimethyl butadiene with isoprene and butadiene, this was successful as the new polymer had similar properties to the natural rubber. He then replaced dimethyl butadiene with styrene and copolymerised with butadiene, the polymer was named as SBR (styrene-butadiene rubber). This polymer was better than natural rubber because it did not wear out quicker than its counterpart, the polymer was later known as Buna-S for commercial purposes. 14 A better synthetic rubber was later developed by copolymerising acrylonitrile with butadiene, the polymer was known as NBR (Nitrile-butadiene rubber), it was the later known as Buna-N for commercial purposes. In 1940, an American inventor named Waldon Semon produced a new synthetic rubber known as Ameripol, this was made by copolymerising butadiene with methyl methacrylate. This synthetic rubber was cheap and easy to make, so it was a no-brainer that it was used in World War 2, and helped out rubber companies such as the Goodyear Tyre and Rubber Company during the war. After the war, the need for natural rubber died down, and the need for synthetic rubbers increased dramatically.15 In the 1960s, EPDM (which is known as Ethylene propylene Terpolymer Rubber) was produced. The rubber is made by copolymerising by a diene derivative, ethylene and propylene. The rubber has many advantageous properties over the synthetic rubbers, one of them is that they have good electrical insulating properties. EPDM rubber are now found in our everyday life such as hose, solar panels, electrical insulation etc.16 The use of synthetic rubber is on a steep rise, and many new rubber materials have been made duri ng the 21st Century. Natural Rubber How it is made? Natural rubber is produced by biosynthetic processes (in the form of latex which is a white liquid that is found when you cut the plant up) in many plants, but mainly from the Hevea Brasiliensis (The rubber tree coming from Brazil). There are two biosynthetic process to make latex. In the first stage, Acetyl-coenzyme A is converted to melavanic acid which then is then converted to iso-pentyl-pyrophosphate. The second process is the polymerisation induced by the first stage of the biosynthesis, from this process latex is created. The rubber form of the latex is then form by coagulating the latex particles. The rubber is made from a polymerisation of naturally occurring cis-polyisoprene. 17 Figure 3:Cis-polyisoprene, natural rubber 18 Properties of Raw Natural Rubber The rubber has a clear colour and hasnt got a well-defined shape and it is soft and sticky, however when the rubber is cooled down it crystalizes, so has a well-defined shape. The rubber has a low tensile strength meaning it tends to break if a low amount of tensile stress is put into it. It has a low abrasion resistance meaning the rubber will wear out quickly. It is soluble to organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). It is insoluble to hydrophilic solvents such as water, acetone, and alcohol. The rubber has a high elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. The rubber can only be elastic between 10 0C to 60 0C, this means under hot conditions the rubber would lose its elasticity. Another pro perty of the natural rubber is that it absorbs a large amount of water this means that it will be always wet and would need to dry it out before the next stage of the process. 19 Advantage of Raw Natural Rubber The hardness of the rubber can easily be adjusted, so can be able to shape or coat any form of objects this is because the rubber has a high elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. It can be used as an electrical conductor or an electrical insulator. Can be able to absorb vibration and noise. It is insoluble to hydrophilic solvents such as water, acetone, and alcohol. It also has a good surface friction so does not slide about easily. Disadvantage of Raw Natural Rubber The rubber can only be elastic between 10 0C to 60 0C, this means under hot conditions the rubber would lose its elasticity. The rubber has a low tensile strength meaning it tends to break if a low amount of tensile stress is put into it. It has a low abrasion resistance meaning the rubber will wear out quickly. It has a poor resistance to any organic compounds this is because It is soluble to organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). Another disadvantage of natural rubber is that it has a poor resistance to ozone meaning that when the ozone reacts with the double bonds it breaks, this causes a crack.20 The crack then grows steadily because of further ozone attacks so this causes the strength of the rubber to decrease massively and cause it to break. Another disadvantage of natural rubber is it has a poor UV resistance this also means that when it reacts with the double bond it breaks; this also means that cracks will from causing the tensile strength to be severely reduced meaning the strength of the rubber would be reduced massively and causing it to break. 20 Another disadvantage is that vulcanization of the rubber can occur spontaneously, so it is hard to control the raw state of the natural rubber. The vulcanization of Natural Rubber To improve the properties of the natural rubber, the process of vulcanisation is used to do this. Vulcanization is a process that involves adding natural rubber to a curing agent such as sulphur. The process is done under heat, so by heating the rubber in the presence of the curing agent the physical and chemical properties of the rubber would be significantly improved. The reason it does is, because when heating the rubber in the presence of the curing agent, the polymer chains are cross-linked by the agent, therefore the free-flowing macromolecules of the polymer chains becomes more rigid.21 Vulcanization must be under controlled condition to avoid creating a massive amount of cross-linking, this means that it will avoid making the rubber less elastic and more brittle. Figure 4: Cis-polyisoprene with sulphur cross-links after vulcanization 23 Properties of Vulcanised Rubber The rubber has a clear colour and it is hard and not sticky, when the rubber is cooled down it crystalizes, so has a well-defined shape. The rubber has a high tensile strength meaning it does not tend to break if a low amount of tensile stress is put into it. It has a high abrasion resistance meaning the rubber will not wear out quickly. It is not soluble to organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). It is insoluble to hydrophilic solvents such as water, acetone, and alcohol. The rubber has a high elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. The rubber can only be elastic between -40 0C to 100 0C which is better than what the given temperature range is for the natural rubber in its raw state, thi s means under hot conditions the rubber would not lose its elasticity. Another property of the natural rubber is that it does not absorb a large amount of water this means it can be dried easily before the next stage of the process. 23 Advantages of Vulcanised Rubber The hardness of the rubber can easily be adjusted, so can be able to shape or coat any form of objects this is because the rubber has a high elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. It can be used as an electrical conductor or an electrical insulator. Can be able to absorb vibration and noise. It is insoluble to hydrophilic solvents such as water, acetone, and alcohol. It is also insoluble to organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). It also has a good surface friction so does not slide about easily. The rubber has a high tensile strength meaning it does not tend to break if a low amount of tensile stress is put into it. It has a high abrasion resistance meaning the rubber will not wear out quickly. The rubber can only be elastic between -40 0C to 100 0C which is better than what the given temperature range is for the natural rubber in its raw state, this means under hot conditions the rubber would not lose its elasticity. Another advantage of the vulcanized rubber is that it does not absorb a large amount of water this means it can be dried easily before the next stage of the process. It has a better resistance to ozone and UV this means that less cracks form than in its raw state. This means that it is less likely to break than the raw natural rubber. Disadvantages of Vulcanised Rubber If the vulcanized rubber is burned it can be toxic for the workers and consumers this is because it contains sulphur cross-links which can form sulphur dioxide. Vulcanization must be under controlled condition to avoid creating a massive amount of cross-linking, this means that it will avoid making the rubber less elastic and more brittle. Another disadvantage of vulcanized rubber, is that when you heat the rubber it melts and then cools quickly, this is quite dangerous for the people who are handling it. Another disadvantage of using vulcanized rubber, is natural rubber are becoming more scarce, therefore the cost of making the vulcanized rubber is increasing. To overcome this problem, scientist have been trying to make vulcanized rubber out of synthetic rubbers such as styrene-butadiene rubbers (SBR), however the problem with this is that it is not cost effect and it is very expensive to make.24 Applications of Natural Rubber and Vulcanized Rubber The main usage of natural rubber is in the motor industry. It is used to make tyres and tubes in vehicles this is because it decreases any generation of heat in the tyres. It also offers high mechanical resistance. Tyres and tubes are used mainly in heavy duty vehicles such as trucks and tractors. 23 Natural rubbers can be used to make toys, footwear, balloons, glue and condoms. Another important application of natural rubbers is that they can be used to make latex gloves. Latex gloves are used in many industries such as the medical industry, chemical industry, and engineering industry, this is because due to the chemical and physical properties of the natural rubber mentioned above it can protect workers and consumers hands from hazardous chemicals.25 There are several applications for the vulcanized rubber. Vulcanized rubbers are much better to produce tyres than natural rubber this is due to having high abrasion resistance meaning tyres wont wear out quickly. The rubber is flexible, this means that it can be used to make hoses, tubes, coats etc Shock absorbers in vehicles are made from vulcanized rubbers due to being able to absorb vibrations easily.26 As the rubber, does not dissolve in water, it can be used to make waterproof clothing and footwears. Another application of using vulcanized rubber is that they can be used to produce cables for telephone housing, and can be able to produce insulations and conductors for electrical instruments. The reason why they are used in electrical instruments, is that have good electrical insulating and conducting properties. Synthetic Rubbers Synthetic Rubbers are made by copolymerising two different monomers under certain conditions. There are 3 conditions (the mixture can be in) it can be done in such as: emulsion, suspension and solution. There are 9 major classes of synthetic rubbers: Styrene-butadiene rubber (SBR), Poly(Butadiene-acrylonitrile) rubbers (NBR), Butyl Rubbers (IIR), Polychloroprene (CR), Ethylene-propylene rubbers (EPDM), Urethane rubbers (EU), Silicone rubbers (VMQ), Fluoroelestomer (FKM), Flurosilicone (FVMQ).27 In this 4 major classes are being discussed. Polychloroprene In 1930, an American scientist named Wallace Carothers and his team produced a compound called chloropropene which then polymerised to form a solid which had a rubbery texture. The team had found out that the properties of this new polymer was similar to that of natural rubber. This polymer was named as Neoprene and was the first commercially successful synthetic rubber.13 Neoprene is produced by the free-radical polymerisation of chloroprene. The chloroprene undergoes polymerisation under aqueous emulsion.28 Properties of Polychloroprene The rubber has a greyish green colour.28 The rubber has a high tensile strength meaning it does not tend to break if a low amount of tensile stress is put into it. It has a high abrasion resistance meaning the rubber will not wear out quickly. It can dissolve with organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). It is insoluble to hydrophilic solvents such as water, acetone, and alcohol. The rubber has a moderate elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. The rubber can only be elastic between -34 0C to 100 0C which is better than what the given temperature range is for the natural rubber, this means under hot conditions the rubber would not lose its elasticity. The rubber has a low flammability, and has a high resistance to weather and ozone.29 Figure 5: Polychloroprene 30 Advantages of Polychloroprene This rubber is tougher than natural rubber because it has a higher tensile strength than natural rubber meaning it does not tend to break if a low amount of tensile stress is put into it. It has a very high resistance to hot conditions and other weather conditions; this means that it does not melt or break easily. Another advantage of polychloroprene rubber is that they have a better resistance to ozone and UV this means that less cracks forms than in its natural counterpart. This means that it is less likely to break than the natural rubber. It has a low flammability and can be able to self-extinguish if it is on fire. The structure of the polychloroprene can be altered to create a new compound which can exhibit different chemical and physical properties. Disadvantages of Polychloroprene The rubber has a poor resistance to aromatic compounds such as benzene derivatives, they also have poor resistance to carbonyl compounds such as ketones and esters, and, also has a poor resistance to strong oxidising agents. Another disadvantage of polychloroprene, is that they are quite expensive to produce. 29 Typical applications of Polychloroprene Production of hoses Making belts Making cable covers for electrical instruments Styrene-butadiene Rubber In the 1930s, a German chemist named Walter bock had developed a new synthetic rubber which had better properties than that of natural rubber. He first tried to copolymerise dimethyl butadiene with isoprene and butadiene, this was successful as the new polymer had similar properties to the natural rubber. He then replaced dimethyl butadiene with styrene and copolymerised with butadiene, the polymer was named as SBR (styrene-butadiene rubber).14 Styrene-butadiene Rubber is produced by the free-radical polymerisation of styrene mixed with butadiene. The monomers undergo free- radical polymerisation under aqueous emulsion. The monomers can also undergo polymerisation in the form of solution.31 Properties of Styrene-butadiene Rubber The rubber has a brown -black colour. 31 The rubber has a high tensile strength meaning it does not tend to break if a low amount of tensile stress is put into it. It has a high abrasion resistance meaning the rubber will not wear out quickly. It can dissolve with organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). It is soluble to hydrophilic solvents such as water, acetone, and alcohol. The rubber has a moderate elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. The rubber can only be elastic between -45 0C to 100 0C which is better than what the given temperature range is for the Polychloroprene, this means under hot conditions the rubber would not lose its elasticity. 29 Figure 6: Styrene-butadiene rubber 32 Advantages of Styrene-butadiene Rubber This rubber is tougher than natural rubber because it has a higher tensile strength than natural rubber meaning it does not tend to break if a low amount of tensile stress is put into it. It has a high abrasion resistance meaning the rubber will not wear out quickly. Another advantage of styrene-butadiene rubber is that it is much more cost effective than natural rubber, and the production of the rubber is much more efficient than its natural counterpart. Disadvantages of Styrene-butadiene Rubber It has a poor resistance to any organic compounds this is because It is soluble to organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). Another disadvantage of natural rubber is that it has a poor resistance to ozone meaning that when the ozone reacts with the double bonds it breaks, this causes a crack. The crack then grows steadily because of further ozone attacks so this causes the strength of the rubber to decrease massively and cause it to break. Fillers like carbon black are needed to strengthen the rubber. Typical applications of Styrene-butadiene Rubber Production of car tyres Making mats Making shoe soles Poly(Butadiene-acrylonitrile) rubbers In 1931, scientists IG Farben developed a synthetic rubber which consisted of copolymerising acrylonitrile with butadiene, the polymer was known as NBR (Nitrile-butadiene rubber), it was the later known as Buna-N for commercial purposes. 14 Styrene-butadiene Rubber is produced by the free-radical polymerisation of styrene mixed with butadiene. The monomers undergo free- radical polymerisation under aqueous emulsion.14 Properties of Poly(Butadiene-acrylonitrile) rubbers The rubber has a yellowish colour.33 It has a high abrasion resistance meaning the rubber will not wear out quickly. It is insoluble with organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). It is insoluble to hydrophilic solvents such as water, acetone, and alcohol. The rubber has a good elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. The rubber can only be elastic between -34 0C to 121 0C which is better than what the given temperature range is for the Polychloroprene, this means under hot conditions the rubber would not lose its elasticity. However, at low temperature, the rubber loses its elasticity.29 Figure 7: Poly(Butadiene-acrylonitrile)34 Advantages of Poly(Butadiene-acrylonitrile) rubbers It has a very high resistance to hot conditions and other weather conditions; this means that it does not melt or break easily. Another advantage of Poly(Butadiene-acrylonitrile) rubber is that they have a better resistance to ozone and UV this means that less cracks forms than in its natural counterpart. This means that it is less likely to break than the natural rubber. It has a high abrasion resistance meaning the rubber will not wear out quickly. Another advantage of Poly(Butadiene-acrylonitrile) rubber is that it has a high resistance in oil this is because It is insoluble with organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). 29 Disadvantages of Poly(Butadiene-acrylonitrile) rubbers At low temperature, the rubber loses its elasticity. Another disadvantage of Poly(Butadiene-acrylonitrile) rubbers, is that they have poor resistance to carbonyl compounds such as ketones and esters, and, also has a poor resistance to strong oxidising agents. 29 Typical applications of Poly(Butadiene-acrylonitrile) rubbers Making nitrile gloves Can be used for O-rings Can be used to make hoses and tubing Ethylene propylene Terpolymer Rubber In the 1960s, EPDM (which is known as Ethylene propylene Terpolymer Rubber) was produced. The rubber is made by copolymerising by a diene derivative, ethylene and propylene. The rubber has many advantageous properties over the synthetic rubbers, one of them is that they have good electrical insulating properties. EPDM rubber are now found in our everyday life such as hose, solar panels, electrical insulation etc. 16 Ethylene propylene Terpolymer Rubber is produced by the copolymerisation of ethylene, propylene and a diene derivative. The monomers under copolymerisation in the form of solution. Figure 8: EPDM 35 Properties of Ethylene propylene Terpolymer Rubber The rubber has a yellowish colour. It has a high abrasion resistance meaning the rubber will not wear out quickly. It is insoluble with organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar). It is insoluble to hydrophilic solvents such as water, acetone, and alcohol. The rubber has a good elastic property, this means that when the rubber is stretched out it gets bigger, but when it is released the rubber goes back into its original shape. The rubber can only be elastic between -40 0C to 149 0C which is better than what the given temperature range is for the Poly(Butadiene-acrylonitrile) rubber, this means under hot conditions the rubber would not lose its elasticity. 29 Advantages of Ethylene propylene Terpolymer Rubber It has a very high resistance to hot conditions and other weather conditions; this means that it does not melt or break easily so does not age very easily. Another advantage of Ethylene propylene Terpolymer rubber is that they have a better resistance to ozone and UV this means that less cracks forms than in its natural counterpart. This means that it is less likely to break than the natural rubber. It has a high abrasion resistance meaning the rubber will not wear out quickly. The rubber is very cost effective, so it is cheaper to make than the other rubber compounds. 29 Disadvantages of Ethylene propylene Terpolymer Rubber It has a poor resistance to oils, this is because It is insoluble with organic solvents such as turpentine (which is an oiled that is attained by the distillation of resin from pine trees), ether, petrol, carbon tetrachloride, and naphtha (which is an oil attained by the distillation of coal tar).29 Typical applications

Myths of Cultures and Civilizations Essay -- Civilization, Myths, Lege

From before the dawn of civilization as we know it, humanity has formed myths and legends to explain the natural world around them. Whether it is of Zeus and Hera or Izanami-no-Mikoto and Izanagi-no-mikoto, every civilization and culture upon this world has its own mythos. However, the age of myth is waning as it is overshadowed in this modern era by fundamental religion and empirical science. The word myth has come to connote blatant falsehood; however, it was not always so. Our myths have reflected both the society and values of the culture they are from. We have also reflected our inner psyche, conscious and unconscious, unto the fabric of our myths. This reflection allows us to understand ourselves and other cultures better. Throughout the eons of humanity’s existence, the myths explain natural phenomena and the cultural legends of the epic hero have reflected the foundations and the inner turmoil of the human psyche. Over the recent centuries, the definition of myth has decayed into a word synonymous with falsehoods and lies. This idea of myths being completely false and therefore useless is a fairly modern one. To combat the rise of empirical science in the 1900s, theologians brought the idea of wholly literal, fundamental religion into being to combat ideas that did not perfectly align with the tenants of the religion (May 24). This was the final death blow to the idea of the metaphysical myth that was already wounded from thousands of years of being denounced as pagan or barbaric. The rise of empirical science also lent to the decay of the meaning of myth. Science was able to explain the natural world far better than a myth ever could; however, it lacked the metaphysical aspect. Due to these rising ideologies, myths hav... ...ng, Ph.D.. n.p. 2002. Web. 25 Mar. 2013. Drysdale, Jilian Miller. â€Å"Faces of the Goddess.† Synchronicity. Dec. 1999/Jan. 2000: 29-31. Sirs Renaissance. Web. 29 Mar. 2014. Freud, Sigmund. The Future of an Illusion. New York: Norton & Company Inc., 1961. Print. Henderson, Joseph. â€Å"Ancient Myths and Modern Men.† Man and his Symbols. Ed. Carl Jung. New York: Doubleday & Company Inc., 1964. 104-158. Print. Jung, Carl. â€Å"Approaching the Unconscious.† Man and his Symbols. Ed. Carl Jung. New York: Doubleday & Company Inc., 1964. 1-104. Kromholz, Susan Foster, and P. Kyle McCarter. â€Å"Why Myth Endures.† Johns Hopkins Magazine. Aug 1990: 32-37. Sirs Issues Researcher. Web, 07 Apr. 2104. May, Rollo. The Cry for Myth. New York: Norton & Company, 1991. Print. Sels, Nadia. Myth, Mind, and Metaphor: On the Relation of Mythology and Psychoanalysis. n.p. 2011. Web. 25 Mar 2014.

Seven Environmental Principles

I. Definition and Importance of Political Science These are the varied definitions of Political Science as it originally emphasized by the Greek term â€Å"polis† for city-state and â€Å"scire† means to â€Å"know†: 1) It is the science that studies the political power and authority of the state and government. 2) It is the systematic study of the institution, organization, processes and laws of the government. 3) It is the study of politics that may influence the government structures and processes in a given society. ) It is how the branches of government perform the various political task such as the delivery of basic services. 5) It is the exercise of sovereign political right of the state and government to carry its task for the improvement of quality of life in the society Generally, the importance of political science is the application of political powers and authority in the realm of government structures. The ordinary citizens may know and learn about their political rights and privileges from a given form of government including the political structure and processes of the state. 1.The knowledge of human rights and privileges will educate the citizens about their role in the political affairs of the state particularly in political rights : a) The right to vote (suffrage);b) The constitutional rights and privileges ( due process of law); c) the right in providing the basic services such as education, health and sanitation, employment and other public support. 2. The study of political science motivates the citizens to participate in the political activities of the state as to achievement the development thrust of the government in relation to the improvement of quality of life. . The political science concepts on democracy, dictatorship and power structures give the citizen full understanding as to the consequences on the individual political action as defined by the political power and authority of the state. 4. The concept of p olitics may well be studied in the political science not simply in the art of persuasion and influence that the citizens learn about also how these political concept area applied in the society. 5.The comprehensive study on the branches, forms and systems of government provide the individual better understanding in the concept of separation of powers, parliamentary system, diplomatic immunity, human rights, general welfare, social services From the understandings of these basic concepts of government, state, laws and institutions those who would study political science must know its importance and function, relationship with other discipline and broader understanding to its specific roles of individual in a civilized society.The students and professionals should not only know the political theories but also deeper insights as to its application in their own field of expertise. Thus the study of political science will also include the empirical investigation of political facts throug h social research and the application of critical thinking. The key words in the comprehensive analysis on the principles of political science are state, government, law, institution, power relationships, legal process, constitutions and politics.These are the important dimensions to study political science that need to be constantly in touch to mold the citizens in achieving quality of life to our society. Definition: Political science is the academic subject centering on the relations between governments and other governments, and between governments and peoples. II. state   (stt) n. 1. A condition or mode of being, as with regard to circumstances: a state of confusion. 2. A condition of being in a stage or form, as of structure, growth, or development: the fetal state. 3.A mental or emotional condition: in a manic state. 4. Informal A condition of excitement or distress. 5. Physics The condition of a physical system with regard to phase, form, composition, or structure: Ice is the solid state of water. 6. Social position or rank. 7. Ceremony; pomp: foreign leaders dining in state at the White House. 8. a. The supreme public power within a sovereign political entity. b. The sphere of supreme civil power within a given polity: matters of state. 9. A specific mode of government: the socialist state. 10.A body politic, especially one constituting a nation: the states of Eastern Europe. 11. One of the more or less internally autonomous territorial and political units composing a federation under a sovereign government: the 48 contiguous states of the Union. adj. 1. Of or relating to a body politic or to an internally autonomous territorial or political unit constituting a federation under one government: a monarch dealing with state matters; the department that handles state security. 2. Owned and operated by a state: state universities. r. v. stat ·ed, stat ·ing, states To set forth in words; declare. III. gov ·ern ·ment ? ? [guhv-ern-muhnt, ? er-muhn t] Show IPA noun 1. the political direction and control  exercised over the actions of the members, citizens, or inhabitants of communities, societies, and states; direction of the affairs of a state, community, etc. ; political administration: Government is necessary to the existence of civilized society. 2. the form or system of rule by which  a state, community, etc. , is governed: monarchical government; episcopal government. . the governing body of persons in a state, community, etc. ; administration. 4. a branch or service of the supreme authority of a state or nation, taken as representing the whole: a dam built by the government. 5. (in some parliamentary systems, as that of the United Kingdom) a. the particular group of persons forming the cabinet at any given time: The Prime Minister has formed a new government. b. the parliament along with the cabinet: The government has fallen. IV. con ·sti ·tu ·tion ? ? [kon-sti-too-shuhn, -tyoo-] Show IPA noun 1. he way in wh ich  a thing is composed or made up; makeup; composition: the chemical constitution of the cleanser. 2. the physical character of the body as to strength, health, etc. : He has a strong constitution. 3. Medicine/Medical, Psychology . the aggregate of a person's physical and psychological characteristics. 4. the act or process of constituting;   establishment. 5. the state of being constituted;   formation. V. A good written constitution must have the following characteristics: 1. ) Broad A constitution must be broad in its scope because it utlines the organization of the government for the whole state. A statement of provisions and functions of the government, and of the relations between the governing body and the governed, requires a comprehensive document. 2. ) Brief A constitution must be brief because it is not the place in which the details of organization should be set forth. Some constitutions have been marred by the inclusion of pure regulation. 3. ) Definite The cons titution must be definite. In a statement of principles of underlying the essential nature of a state any vagueness hich may lead to opposing interpretations of essential features may cause incalculable harm. Civil war and the disruption of the state may conceivably follow from ambiguous expressions in a constitution. VI. Different types of constitutions Introduction There is no doubt that each society has political activity that connects with its social, economic, geographic and political conditions, as well as constitutional studies come at the top of the legal studies due to the subject of the constitutional law connects directly with life and cares of all citizens in the state, rulers or subjects.If the constitutional law cares with the rulers from one corner, but it determines the general aspect of authorities and regime of the governing in the state and draws the limits for specification to each authority and its relations with others. Whatever point of view, there is no dispu te on importance of the constitutional law because it cares with the rulers and subjects and upgrades to the top place. The constitution is a set of the legal rules organize entity of the state and human society that exists among definite geographic space regarding with constitution and legal rules are in permanent and continues movement.Customary Constitutions And Written Constitutions It's known that the rules regarding with any political system of any state, it will be two ways, either resulting from customary without writing out any formal texts, in this case it's said there is customary constitution. The second case it may be wrote down in formal document that is made to be known at the all (Dr. Sabri, Said). So that there two types that are customary constitutions and written constitutions. Customary Constitution The customary is considered the oldest formal resources of the legal rule.It remained the sole source of the constitutional rules in the world till 18th century. It i s theoretic and needed source, whereas gives binding force to the legal rule in the performance. (Dr. Abu Steet, A). English constitution is the clearest example for such type of the constitutional laws because the constitutional laws were formed by the customary in Britain that often represents still constitutional rules. Customary ruels include other written constitutional rules embody in the â€Å"the Greatest Era† of year 1215 A.D. â€Å"Magna Carta and Bill & Rights† of year 1689, and Parliament Act in 1911. Although such constitutional documents vary in Britain, it is not sufficient for political regime in the state that determined by customary rules in general. (Bashir, M. Ibid, page 42). The cause may be that England takes the customary constitution, this is referred to nature of the English people itself who intends to develop its rules and laws quietly without violent, as well as constitutional history began in England early.Moreover, the causes that called m ost of the countries to take with written constituions that were not available in English regime. (Al Sha'r, R. ). The importance of customary rules in the English constitution appears in survey the field that prevailed by it. Because of the English constitution is a set of the systems are often emerged in permanent customaries as long as new necessities made. If the customary rules took great importance in establishing of the constitutional laws in non written constitutions of the countries.Such rules and laws are emerged as a result of following up a public authority in the definite country relating with habit of the any target of the constitutional law without any contrary of the other authorities till it remains in the minds of the people had to respect such rules, consequently it adds binding feature. Written Constitutions The first written constitutions were English colonies constitutions in the North America after its freedom in 1776, USA Constitution in 1787 that still remai ns.Since written constitutions appeared, the idea of constitution liberty prevailed to be a tool for freedom whereas it remains with specific right for the citizen. The idea of written constitution transferred from America to France till it made the first written constitution on 3 September 1791, then coveyed into the remaining European countries. After that range of the written constitution expanded in First World War as well as expanded into the Arabian countries. Consequently, the written constitution acquired political sense because it connects closely with definite matter of the government.According to that written constitutions add on the constitutions rules emphasizing and determining. (Dr. Bashir, M). Flexible And Rigid Constitutions Explainers indicated that flexible constitution that is can be amended by the authorities and with procedures may need for the ordinary laws. When there is flexible constitution such England Constitution, this means that there is no any constitu tion from the form aspect because there is no any conditions vary between the constitution amendments and ordinary legislation amendment, so that establishing authority mixes with legislative authority.As per the rigid constitution, it can't be amended but by authorities and different procedures than such methods that amend the ordinary laws. Whereas as amendment of the rigid constitution vary here than method of the flexible constitution amendment. On the second hand, the rigid constitution has firmness feature as a result of the special procedures that are shall be regarded at amendment of its items. As per the flexible constitution doesn't stipulate definite procedure that should be regarded to amend. Bashir, Al Shafei Mohammed). This doesn't mean that the constitution can't be touched totally and it can't ever amended, but it means making and amendment it. In short, I can sum that the Standard can be taken for the difference between the flexible and rigid constitutions in as dif ficulty and complexity in amendment of the rigid constitution, if this difficulty increases, it will be rigid constitution, while this difficulty decreases, it will be half rigid or half flexible. Constitutional ConventionIt may appear along with written constitution practical needs in which written constitutional rules doesn't complicate; in this case constitutional convention appears along with constitutional flexible rules officially. This convention may interpret or complete deficit in the constitution, but some says that the constitutional convention may be amended as constitutional item. The constitutional convention emerges along with written constitution and it consists with physical and spiritual article, i. e. with following up definite custom then is followed till to be binding matter.Such customs are emerged by political life in the country to exist to the written constitution as complementary or amended rules to some its items. Accordingly, the constitutional convention is either interpretation or complementary, or amended to some items of the constitution. In the interpretation custom, the customs performs with interpreter for ambiguity of the constitutional text. To raise this role, it's supposed there is ambiguity constitutional text, as well as it shows way of application of the texts and conditions.Among examples of the interpreter custom what is made in accordance with French Constitution 1875. As per complementary custom, it overcomes interpreter custom role to play affected role along with written text, it represents in establishing new decision. As shown from its name, complementary custom may emerge to handle deficit problem of the written constitutional text because it supposes that the constitution neglects specific matter. In short that complementary constitution is unlike interpreter custom because it doesn't relay on constitution item, and also it establish new constitutional rule.Among examples is French constitution 1875 provided that election shall be the ballot, and the custom completed this item whereas the election was directly and one degree. (Abu Al Magd, Ahmed Kamal). As per amended custom, that works to amend the constitutional text, it doesn't limited to its ambiguity as interpreter custom or complete what is required of deficit as complete custom, but it aims at amendment of constitutional text and abrogate it provision and add new provision or cancel the standing text. Legal Value Of The Constitutional ConventionThe jurists vary in determine of the legal value of the constitutional convention. Some of them say that its value may be over the constitutional texts, equals to be established in accordance flexible or rigid constitution. But others say that interpreter constitution convention takes degree of the written constitutional text that is emerged beside it. As types of the other constitutional custom takes degree of ordinary law. Reference of this difference is that interpreter constitutional c onvention doesn't establish new constitutional rule other than types. (Hashish, A. H.Dar-al-Nahda Al-‘Arabia). Conclusion In conclusion, I can confirm that there is no any state can live without law and there is not law without sovereignty. So that sovereignty of the law represents in our belief distinctive standard of the state then others of human communities. Sovereignty of the law is not slogans but it is fact shall be committed and obligated till the people find it before them in their daily life. There is no doubt that constitutional law is the first laws. Emphasizing that protection of the constitution from frivolity is to protect of entity of the state.

Pride of China

The four-century-long Han rule is divided into two periods: the Earlier or Western Han and the Later or Eastern Han. In between these two was the short-lived Hsin Dynasty (AD 9-23). The Chinese show their pride in Han accomplishments by calling themselves the Han people. Philosophies and institutions that began in the Chou and Ch'in periods reached maturity under the Han. During Han times, the Chinese distinguished themselves in making scientific discoveries, many of which were not known to Westerners until centuries later. The Chinese were most advanced in astronomy. They invented sundials and water clocks, divided the day equally into ten and then into 12 periods, devised the lunar calendar that continued to be used until 1912, and recorded sunspots regularly. In mathematics, the Chinese were the first to use the place value system, whereby the value of a component of a number is indicated by its placement. Other innovations were of a more practical nature: wheelbarrows, locks to control water levels in streams and canals, and compasses. The Han Chinese were especially distinguished in the field of art. The famous sculpture of the â€Å"Han flying horse† and the carving of the jade burial suit found in Han period tombs are only two superb examples. The technique of making lacquer ware was also highly developed. The Chinese are proudest of the tradition of historical writing that began in the Han period. Ssu-ma Ch'ien (145? -85? BC) was grand historian (an office that combined the duties of court recorder and astronomer) during the time of Wu Ti. His `Historical Records', which took ten years to complete, established the pattern and style followed by subsequent histories. In the Later Han, the historical tradition was continued by the Pan family. Pan Piao, the father, started to bring Ssu-ma Ch'ien's `Records' up to date. The work was continued by his son Pan Ku (twin brother of the general Pan Ch'ao) and was completed by his daughter Pan Chao, China's earliest and most famous woman scholar. Unlike Ssu-ma Ch'ien, the Pan family limited their work to 230 years of the Early Han. This was the first of the dynastic histories, subsequently written for every dynasty. Pan Chao also wrote a highly influential work on the education of women, `Lessons for Women'. Lessons' emphasized the â€Å"virtues† of women, which restricted women's activities. The Confucianism that the Han Dynasty restored differed from the original teachings of Confucius. The leading Han philosophers, Tung Chung-shu and others, used principles derived from the early Chinese philosophy of nature to interpret the ancient texts. The Chinese philosophy of nature explained the workings of the universe by the alternating forces of yin and yang–dark and light–and the five elements: earth, wood, metal, fire, and water. The Han period was marked by a broad eclecticism. Many Han emperors favored Taoism, especially the Taoist idea of immortality. Earlier (Western) Han (202 BC-AD 9). The Han Kao Tsu preserved many features of the Ch'in imperial system, such as the administrative division of the country and the central bureaucracy. But the Han rulers lifted the Ch'in ban on philosophical and historical writings. Han Kao Tsu called for the services of men of talent, not only to restore the destroyed classics but to serve as officials in the government. From that time, the Chinese Empire was governed by a body of officials theoretically selected on merit. Such a practice has few parallels elsewhere at this early date in human history. The new ruler who restored peace and order was a member of the house of Han, the original Liu family. His title was Kuang Wu Ti, â€Å"Shining Martial Emperor,† from AD 25 to 57. During the Later Han, which lasted another 200 years, a concerted but unsuccessful effort was made to restore the glory of the former Han. The Later Han scored considerable success in recovering lost territories, however. Sent to befriend the tribes on the northwestern frontier in AD 73, a great diplomat-general, Pan Ch'ao, eventually led an army of 70,000 almost to the borders of eastern Europe. Pan Ch'ao returned to China in 101 and brought back information about the Roman Empire. The Romans also knew about China, but they thought of it only as the land where silk was produced. The Han Dynasty lasted four hundred years. The term â€Å"The Han people† comes from the name of this dynasty. (The English term for â€Å"China† comes from the name of the previous dynasty Ch'in). The Han dynasty is the East Asian counterpart of and contemporary with Rome in its golden age. During this dynasty, China officially became a Confucian state, prospered domestically, and extended its political and cultural influence over Vietnam, Central Asia, Mongolia, and Korea before finally collapsing under a mixture of domestic and external pressures. The Han ruling line was briefly interrupted by the usurpation of a famous reformer, Wang Mang, whose interlude on the throne from A. D. 9 to 23 in known as the Hsin dynasty. Historians therefore subdivide the Han period into two parts, Former (or Western) Han (capital at Ch'ang-an, present day Xi'an) and Later (Eastern) Han (capital at Loyang).