Foreign Affairs Essay Contest Example For Students

Remote Affairs Essay Contest With the start of an apparently interminable war on fear based oppression, and an unstable United States economy, presently scarcely appears an opportunity to inspect our general arrangement towards every other country, and creating countries specifically. The destruction of the World Trade Center is as yet seething, and our soldiers are walking on Kabul as I compose. Patriotism is at a stature just recently experienced during the World Wars. Each and every other vehicle you see on the expressway has Old Glory gladly flying in their window or on their recieving wire, some privilege close to their Rebel Flag. On a superficial level it shows up the United States has arranged for one increasingly honorable motivation, and underhanded, or those that contradict the US as they are generally called, will clearly fall. We wont represent honest assaults on regular citizens, and those cursed Afghanis and Osama receptacle Laden would do well to stow away. On the off chance that you dont accept this, not exclusively are you un-American, yet you should be a damn fear based oppressor yourself. Unobtrusively, nonetheless, the contention is being made among researchers and free masterminds in the United States that maybe we are not simply the blameless casualties we depict to be in the September 11, 2001 obliteration of the World Trade Center. Some ground breaking minds even anticipated a catastrophe to some degree like this, but not on such a huge scope. Unenlightened individuals inquire as to why something like this could or would happen. What might make such a poor and temperamental nation like Afghanistan chooses to confront the god-like United States? The appropriate response isn't a simple one, and requires an enormous change in what we expect in outside relations, and how we see and treat the remainder of the world all in all. The United States is one of the final super powers of the world, and we have the commitment to keep up and bolster great relations with the littl er and more vulnerable countries all through the world. We should exploit this relationship in a few distinct manners, all without abusing the first people groups or our own capacity. First the U.S. must concentrate on contributing and exchanging with those countries who still can't seem to become financial forces. Second, we should execute a steady international strategy towards the Middle Eastern countries, and all underdeveloped countries by and large. Third, the United States needs to regard the endeavors and aftereffects of the democratization and strict restorations in the Middle East and Latin America, while playing an inactive job in letting the a Western sort of majority rules system follow through to its logical end. Fourth, the U.S. must simplicity and make light of its contention with those civic establishments that hate the Western individuals and their lifestyle. Clearly, remote speculation is important for the eventual fate of creating different countries just as our own. There must be an accentuation on outside venture and exchange, in any case the underdeveloped countries will keep on falling behind monetarily, innovatively, and locally, which could prompt a monetary destruction for the U.S. too. The inquiry at that point emerges concerning what the United States must do so as to have huge exchange concurrences with different nations other than Japan and Mexico. All together for the U.S. to assume an increasingly dynamic job in the monetary and political advancement of a considerable lot of these creating countries, it should initially acknowledge an unexpected way of thinking in comparison to its present one. To start with, it is basic for the United States to assume a comparable job in Latin America to the one Japan has played with huge numbers of the creating countries in East Asia. The U.S. neighbors Latin America, and on the off chance that it needs to assume the job of elder sibling, it must acknowledge the duty. Japan has contributed, e xchanged, and been a guide for a large number of its neighboring nations in East Asia, causing them to develop strategically and monetarily while additionally benefitting financially itself (Japan Remains 1996). The U.S. must understand that the economies of Latin American Nations will have a significant influence later on for our own economy, and that it must start to lead, contribute, and help Mexico, however nations, for example, Peru, Argentina, Bolivia, and Columbia into the twenty first century. The backbone in American international strategy has consistently been to advance and impart majority rules system. Be that as it may, so as to do this in a remote country, the U.S. must have the option to initially build up a suitable financial relationship and framework inside the ideal countries. We ought not expect or need a country to change from an all out dictator government to a market economy; doing so would be a catastrophe. The United States lays a lot on its ideological conv ictions, when there is no compelling reason to do as such. Outside nations look for our capital and exchange courses, not our ethics and culture. We, shockingly, don't feel this is the situation. The US has customarily required win big or bust, with respect to requests on forthcoming exchange accomplices, and political partners. The United States position towards Cuba is an outstanding case of this way of thinking. Rather, the U.S. must be eager to permit creating to countries put resources into U.S. showcases before we put resources into theirs, paying little mind to belief system. Consequently, a feasible fare/import framework will be set up. However, it is basic that the economy of the creating country be observed and run by its own legislature, and the United States should just be there for prompting purposes. At the point when a sensible framework has at long last been accomplished, thennot right awaya increasingly American, free enterprise kind of monetary system will be permi tted to develop. On the off chance that the best test the United States faces is executing an international strategy that is steady all through the Middle East, weve never really shoot ourselves in he foot up until this point. Islamic countries arent prone to be receptive to thoughts, for example, human rights, and vote based system. These countries will never be receptive to western thoughts when the United States keeps on demanding assents against them. The U.S. is fortunate that it has a partner in Saudi Arabia and Israel, permitting them to actualize huge numbers of these international strategy plans against the other Middle Eastern nations, without confronting genuine monetary results in the oil and gas industry. Strangely however, Saudi Arabia is likely as much against western belief systems as any country in the Middle East. Ladies don't have equivalent rights, torment is visit, there is no partition among chapel and state, and Saudi Arabia is incredibly a long way from build ing up any kind of majority rule government (Miller 58). Presently, when the U.S. advances vote based system and human rights, for what reason does it bolster one nation and censure the following? All through the Cold War, American international strategy would offer guide to any country who restricts socialism. So during that time the U.S. built up a youre either with us or against us sort of strategy, non-arrangement. With this arrangement, a large number of the Middle Eastern nations turned out to be supposed adversaries with the U.S., which has prompted distress and contempt of western majority rules systems. In this season of worldwide financial matters, the United States can't single out which nations to put resources into. All together for the U.S. to overcome the difficulties it faces in the Middle East, it must beginning by supporting the whole Middle East. Israel and Saudi Arabia might be the most appealing offers, however Syria and even Iran have tremendous assets that wil l be truly important to our economy in the future.Of course we can't disregard our dear companions off the shore of Miami, Cuba. What edge does a nation like China hold over Cuba other than size? Nothing other than a bigger wellspring of modest work. Our present position on Cuba was right in 1962. Castro was in reality a socialist, however simply after the US, who he went to first, would not support him. In 2001, in any case, it appears to be obvious that Castro has metamorphisized into something different. Castro has done a practically complete 180 in his political way of thinking, and some would contend that Cuba is very nearly a majority rules system as of now. On the off chance that we lifted our inadequate embargoes and opened the exchange lines Cuba, I see no motivation behind why Castro would not open his general public considerably more. Americans are passing up an opportunity to change Cuba, both monetarily and strategically. We get the opportunity to revamp a whole economy starting from the earliest stage, and we should simply put resources into it. These open doors are not speculative either, however genuine as obvious to different nations like Canada and the Europeans. Every other person on the planet knows this as of now since they have made the important mentality alterations and are in there focusing in and getting their hands messy. Castro realizes that he cannot carry out this responsibility of changing his whole structure himself, and it won't be long until he discovers somebody to assist that with willing in all likelihood not be great for the US. It occurred before when the US denied him and he went to the USSR, there is no motivation behind why we should let it happen once more. As the alleged pioneer of the free world we should know better. All the US does is lecture about the significance of strength and free market frameworks, and the requirement for majority rule government. With a model like we are setting, for what reason would it be advisable for anyone to follow? For what reason would it be advisable for us to give it our best shot to guarantee neither makes due in Cuba? Its time and has been for quite a while to bite the bullet and concede we weren't right. The remainder of the free world definitely knows it. They sit in their Cuban financed workplaces, smoking huge Cuban stogies snickering at our pomposity and us. (Smith)Next, the United States must react to the issues of democratization and strict restoration in the Middle East and Latin America. In the Middle East, there is by all accounts the thought that endeavors at democratization would prompt the ruin of minority rights. As Judith Miller brought up, The advancement of free races quickly is probably going to prompt the triumph of Islamic gatherings that have no promise to majority rule government in any conspicuous or significant structure (Miller 59). What the United States must do is set up an authentic or parliamentary procedure that perceives all types of political activity. Just advancing free races would prompt a reaction in democratization endeavors. Th

Causes of mental retardation essays

Reasons for mental hindrance papers So as to be viewed as intellectually impeded, you should have an IQ underneath 75, have critical confinements in at least two versatile aptitude territories, and the condition is available from youth (characterized as age 18 or more youthful). Individuals can be intellectually hindered as every single diverse level. About 78% of intellectually impeded individuals may be a little more slow than the normal individual, while in others it is evident (Arc of New Jersey). There are numerous reasons for mental hindrance. One reason for mental impediment is of hereditary conditions. That incorporates; irregular quality blends from guardians, mistakes when qualities join, overexposure to x-beams, and a lot more reasons. In excess of 500 hereditary sicknesses are related with mental hindrance. Down Syndrome is a case of a chromosomal issue (Mental Retardation Issues). Chromosomal clutters happen from time to time, and are brought about by such a large number of or too scarcely any chromosomes in the rebuild of the chromosomes (The Arc of New Jersey). Another reason is issues during pregnancy. It could occur if the mother drinks or takes drugs while pregnant with the infant. Different dangers incorporate ailing health, certain natural contaminants, and the mother could get sick during the pregnancy. Pregnant ladies who are contaminated with HIV may give it to their youngster. Additionally extremely distressing and physical pregnancies and births can make harm a childs cerebrum (Introduction to Mental Retardation). Mental Retardation additionally happens much of the time after birth. Youth maladies, for example, huge hacks, chicken pox, measles, and hip infection, which may prompt meningitis and encephalitis, can harm the mind, as can mishaps, for example, being hit in the head, close suffocating circumstances, and most different mishaps including the head. Another that can be hurtful to a kid intellectually is natural vapor, lead, mercury, and different risky poisons (Introduction to An American ... <!

Holiday Shopping for Aspiring Minimalists

Holiday Shopping for Aspiring Minimalists Christmas is fast approaching. So is Thanksgiving and Kwanza and Hanukkah and New Years and every other holiday we have commandeered and reappropriated as obligatory gift-giving days. Even Valentines Day, the most insipid example of our commodification of caring, is not far around the corner. So, what better time to revisit three of our favorite holiday-gift-giving essays: 40 Reasons to Avoid Shopping on Black Friday Five Steps Toward a More Meaningful Holiday Season Buying Back the Holiday (Newspaper Interview) Enjoy. Feel free to regift these essays if you find value in them. Tune in to our Twitter and Facebook feeds for more minimalist tips this holiday season. You can also check out Joshuas Minimalist on Christmas television interview: If you cant see the above video, you can watch it on YouTube.

Defining the Meissner Effect in Quantum Physics

The Meissner effect is a phenomenon in quantum physics in which a superconductor negates all magnetic fields inside of the superconducting material. It does this by creating small currents along the surface of the superconductor, which has the effect of canceling out all magnetic fields that would come in contact with the material. One of the most intriguing aspects of the Meissner effect is that it allows for a process that has come to be called quantum levitation. Origin The Meissner effect was discovered in 1933 by German physicists Walther Meissner and Robert Ochsenfeld. They were measuring the magnetic field intensity surrounding certain materials and found that, when the materials were cooled to the point that they became superconducting, the magnetic field intensity dropped to nearly zero. The reason for this is that in a superconductor, electrons are able to flow with virtually no resistance. This makes it very easy for small currents to form on the surface of the material. When the magnetic field comes near to the surface, it causes the electrons to begin flowing. Small currents are then created on the surface of the material, and these currents have the effect of canceling out the magnetic field.

Graduation Speech High School And College - 900 Words

Nowadays, teenagers and young adults are graduating high school and college and are unable to find jobs. A lot of them lack the basic skills needed to survive during adulthood. Institutions exist mainly to educate people on what they need to maintain a somewhat decent lifestyle. Students have been forced to take classes on a variety of subjects throughout high school, most of which have nothing to do with what they need to prepare them for life after education. Even in college, a majority of students do not know what career field they would like to enter, so when they graduate it is hard for them to get a job anywhere. Institutions are not arming students with the proper information needed to excel after education. So, new classes should be created and required for students to pass before graduating. They will be based on basic skills such as money management, customer service skills, and credit understanding. A proposal to the Southern Maryland Higher Education Board of Directors wo uld suffice. They have the authority and means to make change and add classes that can cover these important basic skills. Not only can they be beneficial for the students, but these classes will create jobs for adults. The classes may allow students to go off campus and learn material on a job site. Also, potentially include connections to business owners which may eventually lead to future internships. More importantly, students can gain experience needed to survive in the workplace and beingShow MoreRelatedGraduation Speech On College And High School1199 Words   |  5 PagesCollege Major In this the future is dependent on the amount of education has been attended. It is important to continue in a higher education to have a successful future: earning a college degree is all about opening opportunities in life. 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Evaluation of Waste Tire Devulcanization Technologies Free Essays

string(36) " Heater or Pan process \(Oil law\)\." (INTERNAL REPORT) CENTERPLASTICS COMPOUND ADDITIVES Feb. 2011 – M. S. We will write a custom essay sample on Evaluation of Waste Tire Devulcanization Technologies or any similar topic only for you Order Now Laura Fontana – Centerplastics Enterprise, Ltd Eastern Industrial Road, zip. 516127, Shiwan Town, Boluo Area, Huizhou, DongGuan, GuangDong, P. R. China PPH Chapter 1 – Introduction Approximately 25 potential devulcanization technology researchers and developers were identified throughout the world, however, only a very small number of devulcanization systems are now operating. These are primarily small-capacity systems, which are devulcanizing natural or synthetic rubbers (as opposed to devulcanizing the mixture of rubbers recovered from waste tires). The general types of devulcanization technologies identified and analyzed in the study are shown below. Technology Basis of Processing Zone of Reaction Chemical Chemicals/chemical reactions Surface of particles Ultrasonic Ultrasonic waves Throughout particles Microwave Microwaves Throughout particles Biological Microorganisms Surface of particles Other Mechanical Steam Surface of particles Key findings Reliable information and data on devulcanization of waste tire rubber are difficult to obtain due to proprietary claims, efforts to hide poor or infeasible process performance and product quality, and the limited number of technology researchers and developers and of peer-reviewed data. Reliable data relating waste tire characteristics, devulcanized rubber quality, end product performance, and production costs is scarce.  · Only a very small number of low-capacity devulcanization systems are operating in the United States (at approximately 50 Kg /hr, all RD scale, mechanical, or ultrasonic). No proven commercial capacity units could be found that are currently devulcanizing waste tires, for example, at 500 Kg/hr or greater. The likely reasons include insufficient product quality and high costs of production.  · In terms of the potential of producing high-quality devulcanized rubbers (for example, high strength), the best technology appears to be ultrasonic, based on the current state of the art.  · Devulcanization of single rubbers has much more history than that of multi-rubber mixtures such as waste tires. Only a few companies devulcanize single formulation rubber as a result of captive conversion or merchant scrap recovery from manufacturing. The production of devulcanized rubber from home manufacturing scrap in the U. S represents about 1 to 2 percent of total U. S. rubber consumption.  · The quality of devulcanized single rubbers is higher than that of devulcanized multiple rubbers.  · Devulcanization that depends on surface devulcanization technologies (for example, chemical and mechanical) appears destined in the near term to produce low- or medium-quality devulcanized rubber material. The estimated cost for producing devulcanized materials from waste tires is $0. 3 to $0. 6/Kg  ± 30 percent, if including the cost of crumb rubber feedstock. This range of production costs is significantly greater than that of virgin rubbers. A typical tire compound contains the following constituents: Table 1. Composition of Tires Passenger Tire Constituents Common Materials Natural rubber 14 % Natural rubber Synthetic rubber 27% SBR, butadiene rubber Carbon black 28% Carbon black Steel 14%–15% Steel Fabric, fillers, accelerators, antiozonants, etc. 16%–17% Polyester, nylon, aromatic oil, coumarine resin, silica, bonding agent, stearic acid, ntioxidant, processing chemicals, sulfur, zinc oxide Truck Tire Natural rubber 27% Natural rubber Synthetic rubber 14% Synthetic rubber Carbon black 28% Carbon black Steel 14%–15% Steel Fabric, fillers, accelerators, antiozonants, etc. 16%–17% Polyester, nylon, aromatic oil, stearic acid, antioxidant, wax, processing chemicals, sulfur, zinc oxide Source: Rubber Manufacturers Association, 2004. †¢ Reclaiming is a procedure in which scrap tire rubber or vulcanized rubber waste is converted—using mechanical and thermal energy and chemicals—into a state in which it can be mixed, processed, and vulcanized again. The principle of the process is devulcanization (Franta, 1989). Historically and practically, in the concept of rubber reclaiming, devulcanization consists of the cleavage of intermolecular bonds of the chemical network, such as carbon-sulfur (C-S) and/or sulfur-sulfur (S-S) bonds, with further shortening of the chains also occurring (Rader, 1995). This description of devulcanization is different than that given below, which is limited to chemical interactions involving sulfur atoms. †¢ Reclaim is an interesting raw material as it reduces the production costs of new rubber articles, due to shorter mixing times and lower power consumption. The processing temperature is lower, and the material has a higher dimensional stability during calandering and extrusion due to the remaining three-dimensional network. The most important advantage of cured articles containing reclaim in terms of properties is an improvement of aging resistance. †¢ Devulcanization is the process of cleaving the monosulfidic, disulfidic, and polysulfidic crosslinks (carbon-sulfur or sulfur-sulfur bonds) of vulcanized rubber. Ideally, devulcanized rubber can be revulcanized with or without the use of other compounds. The different types of devulcanization processes also modify other properties of the rubbers. These processes cause diminution of some properties over those of the parent rubber. Ideally, devulcanization would yield a product that could serve as a substitute for virgin rubber, both in terms of properties and in terms of cost of manufacture. Polymers can be divided into two groups: thermoplastics and thermosetting materials. Thermoplastics soften when heated, making it possible to (re-)shape them at higher temperatures. Thermosetting materials, like rubbers, are crosslinked on heating and therefore cannot be softened or remodeled by raising the temperature. Therefore, thermosets are more difficult to recycle compared to thermoplastics. The three-dimensional network has to be broken in order to make the material (re-)processable: the so-called reclaiming process. In this process, either sulfur crosslinks connecting the polymer chains or carbon-carbon bonds in the polymer backbone are broken. The first mechanism is preferred, as the backbone of the polymer remains intact. Scission can be obtained by heat, shear or chemical reactions. Basically, processes of rupturing the rubber network by crosslink or main-chain scission can be classified into five main groups. †¢ Thermal reclaiming; †¢ Thermo-mechanical reclaiming; †¢ Mechano-chemical reclaiming; †¢ Reclaiming by radiation, and †¢ Microbial reclaiming. In actual practice, combinations of thermal and mechanical reclaiming are mostly used, with in some cases the addition of a devulcanization aid for chemical reclaiming. 1. 1-Thermal Reclaiming For this kind of processes, heat (often combined with addition of chemicals) is used to break the sulfur bonds and thus to plasticize the rubber. Hall patented in 1858 one of the oldest and most simple processes in the rubber reclaiming industry, the Heater or Pan process (Oil law). You read "Evaluation of Waste Tire Devulcanization Technologies" in category "Papers" In this process, finely ground natural rubber powder is mixed with oils and reclaiming agents and treated with high or medium pressure steam at temperatures varying from 170 °C to 200 °C. The reclaiming time is long and the homogeneity of the reclaim is low, but this process is able to reclaim a large number of polymers: natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR) and butyl rubber (IIR) and the equipment is rather inexpensive. The use of the heater or pan process became less popular after Marks patented the Digester or Alkali process in 1899. The fibers of the rubber scrap, remnants of the tire carcass, were first removed by mixing it with alkali, water, plasticizing oils and, if needed, chemical peptizers. The mixture was heated in a jacketed, agitator equipped autoclave to 180-210 °C. The most important disadvantage of this process is the pollution generated by the chemicals. Modifications of this process minimized the pollution, but increased the reaction times. Processes with short reaction times are for example the High Pressure Steam processes or the Engelke process. In the first process, a fiber-free, coarse ground rubber is mixed with reclaiming agents, and reclaiming is done in a high-pressure autoclave at approximately 280 °C. In the latter process, coarse ground rubber scrap is mixed with plasticizing oils and peptizers and is put into small autoclaves. The material is heated to very high temperatures for a short period of 15 minutes, after which it is lead through refiners (mills with very narrow gaps) and strainers. . 1. 1 – Steam With or Without Chemicals (Digester, DD-CR, HTDD-CR) Steam devulcanization of crumb rubber uses a steam vessel equipped with an agitator for continuous stirring of the crumb rubber while steam is being applied. There are two variants of the basis steam process, namely, â€Å"wet† and â€Å"dry. † The wet process uses caustic and water mixed with the rubber crumb, while the dry proce ss uses only steam. If necessary, various reclaiming oils may be added to the mixture in the reaction vessel. In one case, a wet process using diaryl disulfide and reclaiming oils with saturated steam at 190 °C (374 °F) was fed finely ground NR and synthetic rubber scraps. A charge of about 440 lbs. was partially devulcanized after 15 to 17 hours of processing. This process required 12 hours at ambient temperature for pre-treatment and 3 to 5 hours for steam or high temperature treatment (Adhikari, et al. , 2000). The dry process digester has the advantage of generating less pollution than the wet process. Scrap rubber containing natural and synthetic rubbers can be reclaimed by the steam digestion process. Reclaiming oil used for this process has molecular weights between 200 and 1000, consisting of benzene, alkyl benzene, and alkylate indanes. A generic processing diagram for steam devulcanization is shown in Figure A. Figure A. Schematic Diagram of a Steam Devulcanization System Devulcanized Rubber Dehydrating System Steam Reactor Rubber Crumb Chemical(s) Liquid By-Product 1. 2 – Thermo-Mechanical Reclaiming The thermo-mechanical reclaiming processes make use of shearing forces to plasticize the rubber. Energy is introduced into the materials, resulting in a significant temperature increase, high enough to cause thermal degradation. The Lancaster-Banbury process is one of the oldest processes. Fiber-free coarse ground rubber scrap is mixed with reclaiming agents and sheared in a high speed, high-pressure internal mixer. When a continuously working, multiscrew devulcanizer is used instead of the internal mixer, the process is called the Ficker reclaiming process. One of the first continuous reclaiming processes is the so-called reclaimator process. This is basically a single screw extruder that has been adapted to reclaim fibre-free rubber scrap in very short extrusion times. The short extrusion times make this method suitable for SBR, that tends to harden when longer recycling times are applied. Another mechanical reclaiming process is the De-Link process. In this process finely ground rubber powder is mixed with the De-Link masterbatch (DeVulc) : a zinc salt of dimethyldithiocarbamate and mercaptobenzothiazole in a molar ratio of 1:1 to 1:12, dispersed in thiols and activated by stearic acid, zinc oxide and sulfur. Advantages of the process are its simplicity and the fact that standard rubber equipment is used. No evidence is available to demonstrate that the De-Link process is used beyond laboratory or pilot scale. The Toyota process is another development of mechanical reclaiming. In this process a mixture of ground rubber, virgin rubber, oils and a devulcanization aid is masticated on a two-roll mill or in an extruder. Mechanical devulcanization is achieved through the repeated deformation of rubber particles under specific conditions of temperature and pressure. The result is a devulcanized rubber, ready for further processing. Toyota developed another continuous process, Toyota Gosei (TG) combining pulverization, reclaiming and deodorization. The rubber waste has to be ground to a particle size of 5-10 mm before it can be fed into a â€Å"modular screw-type reactor† with a pulverization zone and a reaction zone. The operating temperature is in the range of 100-300 °C and 100-900 rpm screw speeds are applied, the process requires about 100 Kw (kilowatts) to process 200 to 300 kg (kilograms)/hr of rubber, or approximately 0. 4 kW/kg. By manipulating screw configuration and rotational speed, and processing temperature, researchers are able to control the duration of the treatment. In this way they can, to some extent, control the properties of the devulcanizate. The TG process has been primarily, if not exclusively, used to devulcanize specific types of rubber compounds, such as NR and SBR. 1. 3 – Mechano-Chemical Reclaiming Mixing of the rubber powder with a peptizer (chemicals used to reduce the viscosity of NR) and a reclaiming agent prior to the mechanical breakdown of the material improves the reclaiming process. The devulcanization aid is supposed to selectively break the sulfur crosslinks in the rubber network. This chemical breakdown is combined with input of thermal and/or mechanical energy, as the rate of this process is sufficiently high only at higher temperatures. The most common devulcanization aids are disulfides, e. g. aryl disulfides or diphenyl sulfides, thiophenols and their zinc salts and mercaptanes. These chemical compounds are radical scavengers: they react with the radicals generated by chain- or crosslink scission and prevent recombination of the molecules. Typical concentrations for the reclaiming agents are 0. 5 to 4 wt%. Suitable peptizers are aromatic and naphthenic oils with a high boiling point. Figure B. Schematic Diagram of a Chemical Devulcanization System Devulcanization Agent Rubber Crumb Mixer Heated Extruder Devulcanized Filter Dryer Rubber Liquid By-Product Unfortunately, a detailed accounting of test materials, performance parameters, and conditions is lacking, thus inhibiting the extent of interpretation of the data. Comparisons of data are primarily limited to comparing the properties of virgin rubbers with compounds containing the virgin and devulcanized material at concentrations of about 30 percent devulcanized material. As shown by the data in the table, the properties of the mixtures containing devulcanized material are in general moderately lower than those of their virgin counterparts. The reported data reflect two different types of chemical devulcanization technologies. Table 2. Properties of Waste Tire Rubber Devulcanized Using Chemical or Chemical/Mechanical Technology Generic Technology Technology Surrogate Test Rubber Compound s % Devulc (or Ground) Mat’l Mooney Viscosity (ML-4 @ 212 °F) Tensile Strengt h (lbs/in2) 300% Modulus (lbs/ in2) Elongation to Break (%) Chemical STI-K Polymers DeLinka NR 0 61. 9 4,270 1,987 534 NR w/devulc NR 30 72. 3 4,020 2,151 489 Virgin SBR (1520) 0 96. 6 3,880 3,059 358 SBR (1520) w/devulc SBR 30 109. 2 3,580 2,923 345 Chemical/ Mechanical LandStar/ Guangzhou Research Instituteb NR 100 28. 4 680 SR 100 17. 2 514 AMRc Powder (devulc. additive) 100 23. 9 640 Tread Tire Compoundd 0 20. 3 772 28. 6 19. 7 628 Light Duty Truck Tire Compounde 0 23. 8 536 28. 6 20. 5 500 1. 4 – Reclaiming by Irradiation Bond type Dissociation energy (KJ/mol) C-C 349 C-S 302 S-S 273 Polysulfidic 253 Table 3. Typical bond energies 1. 4. 1 – Ultrasonic Rubber devulcanization by using ultrasonic energy was first discussed in Okuda and Hatano (1987). It was a batch process in which a small piece of vulcanized rubber was devulcanized using 50 kHz ultrasonic waves after treatment for 20 minutes. The process apparently could break down C-S and S-S bonds, but not carbon-carbon (C-C) bonds. The properties of the revulcanized rubber were found to be very similar to those of the original vulcanizates. One continuous process for devulcanization of rubbers is based on the use of high-power ultrasound electromagnetic radiation. This is a suitable way to recycle waste tires and waste rubbers. The ultrasonic waves, at certain levels, in the presence of pressure and heat, can quickly break up the three-dimensional network in crosslinked, vulcanized rubber. The process of ultrasonic devulcanization is very fast, simple, efficient, and it is free of solvents and chemicals. The rate of devulcanization is approximately one second. This may lead to the preferential breakage of sulfidic crosslinks in vulcanized rubbers. (Isayev, 1993; Yu. Levin, et al. , 1996; Isayev, et al. , 1997; Yun, et al. , 2001; Yun Isayev, April 2003). Under a license from the University of Akron for the ultrasonic devulcanization technology, NFM Company of Massillon, Ohio, has built a prototype of the machine for ultrasonic devulcanization of tire and rubber products (Boron, et al. 1996; Boron, et al. , 1999). It was reported that retreaded truck tires containing 15 and 30 weight percent (percent by weight) of ultrasonicallydevulcanized carbon black-filled SBR had passed the preliminary dynamic endurance test (Boron, et al. , 1999). Extensive studies on the ultrasonic devulcanization of rubbers, and some preliminary studies on ultrasonic decrosslinking of crosslink ed plastics, showed that this continuous process allows recycling of various types of rubbers and thermosets (Isayev, 1993; Hong Isayev, 2002 (pp. 160–168); Shim, et al. 2002; Shim Isayev, 2003; Gonzalez-de Los Santas, et al. , 1999). As a consequence of the process, ultrasonically-devulcanized rubber becomes soft, therefore enabling this material to be reprocessed, shaped, and revulcanized in very much the same way as virgin rubber. This new technology has been used successfully in the laboratory to devulcanize ground tire rubber (commonly referred to in the industry as GRT) (Isayev, et al. , 1995; Yun, et al. , 2001; Boron, et al. , 1996), unfilled and filled rubbers N (Hong Isayev, 2001; Yu. Levin, et al. , 1996; Isayev, et al. , 1997; Diao, et al. 1998; Shim, et al. , September 2002; Ghose Isayev, 2003), guayule rubber (Gonzalez-de Los Santas, et al. , 1999), fluoroelastomer, ethylene vinyl acetate foam, and crosslinked polyethylene (Isayev, 1993; Isayev Chen, 1994). After revulcanization, rubber samples exhibit good mechanical properties, which in some cases are comparable to or exceeding those of virgin vulcanizates. Structural studies of ultrasonically-treated rubber show that the breakup of chemical crosslinks is accompanied by the partial degradation of the rubber chain; that is, the C-C bonds (Isayev, et al. , 1995; Tukachinsky, et al. 1996; Yu. Levin, et al. , 1997 (pp. 641–649); Yushanov, et al. , 1998). The degree of degradation of C-C bonds can be substantial, depending on conditions. The mechanism of rubber devulcanization under ultrasonic treatment is presently not well understood, unlike the mechanism of the degradation of long-chain polymer in solutions irradiated with ultrasound (Suslick, 1988). Ultrasonic devulcanization also alters the revulcanization kinetics of rubbers. The revulcanization of devulcanized SBR appeared to be essentially different from those of virgin SBR (Yu. Levin, et al. , 1997, pp. 120–128). The induction period is shorter or absent for revulcanization of devulcanized SBR. This is also true for other unfilled and carbon black-filled rubbers such as ground rubber tire (GRT), SBR, natural rubber (NR), ethylene propylene diene monomer (EPDM), and butadiene rubber (BR) cured by sulfur-containing curative systems, but not for silicone rubber cured by peroxide. Ultrasonically-devulcanized rubbers consist of sol and gel. The gel portion is typically soft and has significantly lower crosslink density than that of the original vulcanizate. Due to the presence of sol and soft gel, the devulcanized rubber can flow and is subject to shaping. Crosslink density and gel fraction of ultrasonically-devulcanized rubbers were found to correlate by a universal master curve (Yushanov, et al. , 1996; Diao, et al. , 1999; Yushanov, et al. , 1998). This curve is unique for every elastomer due to its unique chemical structure. In a comparative analysis of ultrasonically reclaimed unfilled SBR, NR and EPDM rubbers, it was found that it was more difficult to reclaim EPDM than NR and SBR. Reclaiming of EPDM roofsheeting resulted in a good quality reclaim, which after revulcanization showed more or less equal mechanical properties compared to the virgin compound. The surface smoothness of the revulcanized compounds could be controlled by the process conditions. Most companies marketing ultrasonic devulcanization technologies are utilizing very similar technologies involving cold feed extruders and varying physical arrangements of ultrasonic equipment. Ultrasonic devulcanization technology is actually composed of a â€Å"devulcanization system†Ã¢â‚¬â€ namely, extrusion and ultrasonic processing. Two key differences in some cases are the equipment and materials used to generate the ultrasonic energy required for the process, and the positioning of the transducer(s) relative to the extruder. Two different arrangements of ultrasonic devulcanization systems are shown in Figures C and D. In this type of devulcanization system, size-reduced rubber particles are loaded into a hopper and are subsequently fed into an extruder. The extruder mechanically pushes and pulls the rubber. This mechanical action serves to heat the rubber particles and softens the rubber. As the softened rubber is transported through the extruder cavity, the rubber is exposed to ultrasonic energy. The resulting combination of heat, pressure, and mechanical mastication is sufficient to achieve varying degrees of devulcanization. The time constant of the devulcanization process takes place in seconds. Essentially all of the rubber entering the process is discharged from the extruder in semi-solid product stream. Process losses would be primarily those due to emissions of fine particulates or of gases, if any, generated due to the mechanical and thermal processes occurring during the devulcanization process. After exiting through the extruder die, the rubber is passed through a cooling bath and then dried. Figure C. Schematic Diagram of an Ultrasonic Devulcanization System Showing a Mid- Extruder Location for the Ultrasonic Subsystem Ultrasonic Processing Zone Cooling Bath Devulcanized Rubber Extruder Rubber Crumb Feed Hopper Figure D. Schematic Diagram of an Ultrasonic Devulcanization System Showing the Ultrasonic Subsystem Located at the Discharge End of the Extruder Ultrasonic Processing Zone Cooling Bath Devulcanized Rubber Feed Hopper Extruder Rubber Crumb Table 4. Properties of Waste Tire Rubber Devulcanized Using Ultrasonic Technology Technology Surrogate Test Rubber Compound s % Devulc or (Ground) Mat’l Mooney Viscosity (ML-4 @ 212 °F) Tensile Strength (lbs/in2) 100% Modulus (lbs/ in2) 300% Modulus (lbs/ in2) Elongation to Break (%) U of Akron SBR 1848a 0 2,415 740 780 SBR (1848) w/devulc SBRa 10 1,075 790 540 SBR (1848) w/whole train reclaima (10) 1,940 760 660 SBR (1848) w/30 mesh buffingsa (10) 1,440 780 480 100% NR (SMR CV60) 0% SBR (23. 5% bound styrene, and Duraden 706)b 0 3,263 116 670 NR (SMR CV60) 25% SBR (23. 5% bound styrene, and Duraden 706)b 0 1,885 123 600 NR (SMR CV60) w/devulc SBR (23. 5% bound styrene, and Duraden 706)b 25 580 123 380 NR (SMR CV60) 50% SBR (23. 5% bound styrene, and Duraden 706)b 0 406 131 390 Technology Surrogate Test Rubber Compound s % Devulc or (Ground) Mat’l Mooney Viscosity (ML-4 @ 12 °F) Tensile Strength (lbs/in2) 100% Modulus (lbs/ in2) 300% Modulus (lbs/ in2) Elongation to Break (%) NR (SMR CV60) w/devulc SBR (23. 5% bound styrene, and Duraden 706)b 50 363 123 320 NR (SMR CV60) 75% SBR (23. 5% bound styrene, and Duraden 706)b 0 363 145 295 NR (SMR CV60) w/devulc SBR (23. 5% bound styrene, and Duraden 706)b 75 276 131 250 100% SBR (23. 5% bound sty rene, and Duraden 706)b 0 290 152 200 100% SBR (23. 5% bound styrene, and Duraden 706)b 100 290 138 180 Table 5. Percent Change from Virgin with Selected Devulcanization Rubber Formulations Test Rubber Compounds (grade) Parts or % % Devulc. or (Groun d) Mat’l. Hardnes s Shore Tear Strengt h Tensile Strengt h 100% Modulu s 300% Modulu s Elongatio n to Break Chemical STI-K Polymers DeLinka NR w/devulc NR 30 -5. 9% 8. 3% -8. 4% SBR (1520) w/devulc SBR 30 -7. 7% -4. 4% -3. 6% Kyoto Universityb Truck tire (93 NR+ 7 BR) 84 NR+ 6 BR + 20 devulc 18 8. 1% -2. 3% 2. 6% 0. 0% 74 NR+ 6 BR + 40 devulc 33 12. 9% -11. 9% 28. 2% -17. 4% 65 NR + 5 BR + 60 devulc 46 11. 3% -19. 1% 23. 1% -13. 0% LandStar/Guangzhou R Ic 100 SIR 10 + 50 devulc SIR vs. Case 1 33 4. 3% -23. 7% 6. 7% -6. 7% SIR vs. Case 2 33 6. 5% -23. 0% 11. 5% -8. 6% Tread Tire Compound 0 NR + 30 SR + 20 CIS-BR +40 AMR 28. 6 6. 7% -17. 3% -3. 0% -18. 7% Light Duty Truck Tire Compound 30 NR + 70 SR + 0 CIS-BR + 40 AMR 28. 6 1. 6% -10. 9% -13. 9% -6. 7% Retread Tire Compound c65 NR + 35 SR +40 AMR 28. 6 6. 3% -8. 6% -10. 3% -16. 8% Ultrasonic University of Akrond Versus Akrochem SBR (1848) SBR w/devulc SBR 10 -55. 5% 6. 8% -30. 8% Test Rubber Compounds (grade) Parts or % % Devulc. or (Groun d) Mat’l. Hardnes s Shore Tear Strengt h Tensile Strengt h 100% Modulu s 300% Modulu s Elongatio n to Break SBR w/whole Tire Reclaim 10 -19. 7% 2. 7% -15. 4% SBR w/30 Mesh Buffings 10 -40. 4% 5. 4% -38. % Natural Rubber and SBR versus devulc Base 100% NR (SMR CV60) 0% SBR (23. 5% bound styrene, and Firestone Duraden 706) 0 Add 25% SBR, 75% NR 0 -42. 2% 6. 3% -10. 4% Devulc SBR replaces SBR 25% devulc SBR, 75% NR 25 -69. 2% 0. 0% -36. 7% 50% devulc SBR, 50% NR 50 -10. 7% -5. 6% -17. 9% 75% devulc SBR, 25% NR 75 -24. 0% -10. 0% -15. 3% SBR versus devulc SBR 100% devulc SBR 100 0. 0% -9. 5% -10. 0% Heavy carbon-blacked rubber is the hardest to devulcanize, and silica, or other mineral-filled EDPM, is the easiest. Reincorporation of the devulcanized rubber is typically in the 20 to 40 percent range. Devulcanized single-product rubber applications are wide ranging. The reclaimed product may be reintroduced into the same end product or one with more tolerant performance characteristics for the devulcanized rubber. Devulcanized rubber seems to have advantages in bonding, strength, and tread integrity above the properties of crumb rubber, which acts only as a â€Å"rubber†-like filler. According to one developer of a devulcanization process, about 3 to 10 percent of the final product can be blended into virgin material before performance properties are affected. Variations of a few percent are reported by developers of devulcanization when they vary process run conditions. Run-to-run variations are normally acceptable. Devulcanized single rubber products have a much lower degree of degradation than multiple rubber mixtures with devulcanized rubber. Virgin single-grade SBR—or natural rubber replacement with devulcanized material shown by the STI-K and the University of Akron datasets —has, at worst, a reduction of 10 percent in tensile strength, modulus, or elongation. In some cases, the addition of devulcanized rubber causes a major reduction in performance of some properties, along with improvements in one or two properties (hardness and modulus). Because the modulus is the measure of deformation—that is, tension (stretching), compression (crushing), flexing (bending), or torsion (twisting). Similarly, the increase in hardness could be an improvement or detraction, depending on the application. The devulcanized rubber properties displayed are not necessarily optimized for a specific end use. Formulators will likely be able to incorporate devulcanized rubber along with other formulation components to achieve a higher level of final product performance. Key product performance variables are level of contamination, number of rubber types in the rubber mixtures, and additives used by the formulations. The effect of additives was discussed previously under â€Å"Product Characteristics. † The number of types of rubber in waste tires is one of the most important factors affecting quality of devulcanized waste tire rubber. Optimizing a devulcanization process is very difficult when more than one type of rubber is involved. Depending on the process used, process conditions, the material, and the blending level of the devulcanized rubber, most properties will be reduced by a few percent to more than two-thirds of those of the virgin material. In situations where the devulcanized rubber properties are within 10 percent of the original rubber material, blending would seem to be an attractive opportunity that offers the potential of adding a low-cost recycled substitute. The best operating model for devulcanizers of single rubber formulation is a dedicated devulcanization line (or long run) of specific rubber. Smaller volumes of single formulations require incurring extra costs for downtime and lost product caused by the cleanout between runs. The devulcanized rubber itself and some of its additives and fillers—such as carbon black— presumably add value. These fillers take the place of new additives and fillers that would otherwise be necessary. 1. 4. 2 – Microwave Microwave technology has also been proposed to devulcanize waste rubber (Fix, 1980; Novotny, et al. 1978). This process applies the heat very quickly and uniformly on the waste rubber. The method employs the application of a controlled amount of microwave energy to devulcanize a sulfur-vulcanized elastomer— containing polar groups or components—to a state in which it could be compounded and revulcanized into useful products such as hoses. The process requ ires extraordinary or substantial physical properties. On the basis of the relative bond energies of C-C, C-S, and S-S bonds, the scission of the S-S and carbon-sulfur crosslinks appeared to take place. However, the material to be used in the microwave process must be polar enough to accept energy at a rate sufficient to generate the heat necessary for devulcanization. This method is a batch process and requires expensive equipment. Figure E. Schematic Diagram of a Microwave Devulcanization System Rubber Crumb Microwave Unit Devulcanized Rubber Cooling System 1. 5 – Microbial Reclaiming Thiobacillus-bacteria are able to oxidise the sulfur in polysulfonic bonds to sulphate. This reaction is limited to a surface layer of the rubber with a thickness of less than 1 ? and the oxidation takes several weeks. The thiophilic bacteria Sulfolobus Acidocaldarius is able to split carbonsulfur bonds in a stepwise oxidation reaction of the carbon-bound sulfur into a sulfoxide, a sulfone and finally to a sulphate8, 9. The disadvantage of these processes is the low devulcanization rate. Apparently, these types of biological devulcanization processes are exclusively or primarily limited to the surface layers of the elastomers (Christiansson, et al. , 1998). This circumstance may explain the overall low rates of desulfurization based on total mass processed. Figure F. Schematic Diagram of Biological Devulcanization System Microorganisms and Host Media Mixer/ Reactor Rubber Crumb Devulcanized Rubber Dryer Filter By-Product Gases Liquid By-Product Chapter2 – Cost Analysis Given the lack of information in the literature, the cost estimates are based on a synthesis of information and data from multiple sources for a given generic type of technology; The analysis was generally performed by determining the costs (capital and operating and maintenance) of the processes and equipment described in the available literature. The cost analyses were conducted for three technologies that use different processing approaches: chemical, ultrasonic, and mechanical. * The key processing elements of each of these technologies have been previously described in this report, and they serve as the primary basis of estimating capital and operating and maintenance costs. The data in Table 6 summarize the capital costs and operating and maintenance costs for the technologies analyzed. The data for the capital cost analysis include an allowance for engineering services for the construction of the facility. The information shows that the capital costs for the processes vary from about $92,000 to about $166,000. ** Insufficient technical information and data were found during the study to enable reliable cost analyses for other devulcanization technologies. Table 6. Estimated Unit Costs for the Production of Devulcanized Rubber Item Mechanical Chemical Ultrasonic Capacity (lb/hr) 100 75 75 Capital Cost ($) 92,000 166,000 163,000 O Cost ($) 135,000 172,000 136,000 Amortized Capital and O ($) 143,000 186,000 150,000 Amortized Unit Cost ($/lb) 0. 7 1. 2 1. 0 Interest rate: 6% per year; Amortization period: 20 years Similarly, the data in the table indicate that the operating and maintenance costs for facilities of this type range from about $135,000 to $172,000. The operating cost estimates include the cost of crumb rubber feedstock for each of the processes. Based on the relative small size of the facilities, the costs of the rental of a building for processing in operating and maintenance are included. This eliminated the cost of building a structure. As shown in the Table, the estimated amortized costs for producing devulcanized rubber are: $1. 0/lb for the ultrasonic process, $1. 2/lb for the chemical process, and $0. 7/lb for the mechanical process. The analysis used an interest rate of 6 percent per year and an amortization period of 20 years. Due to uncertainties represented by the lack of detailed technical data and operating history for the technologies, the accuracy of the cost estimates is +/- 30 percent. As mentioned earlier, these costs reflect production at low capacities. Some reduction in unit cost would likely occur due to economies of larger scale production. However, estimating reduction in unit cost is difficult because of the lack of data relating to production costs to different levels of throughput capacity for particular devulcanization technologies. For the size of operations considered in this analysis, labor costs are a substantial portion of the production costs. It is very difficult, however, to estimate the magnitude of any potential reductions in unit labor costs that might occur if processing capacities were increased substantially. All circumstances considered, any estimates of commercial production costs for devulcanization of waste tire rubber are highly speculative at best. The best estimate of the study team is that perhaps production costs could be reduced by 25 to 30 percent if processing capacities were increased by a factor of approximately 5 to 10. The estimates of processing costs developed in this study do not include the costs of pollution control. The chapter lists the types of emissions that could be expected. The difficulty of permitting such a process and the cost of compliance with environmental regulations may comprise a significant barrier to the implementation of this technology. Conceivably, pollution control costs could add 10 to 30 percent to the cost of devulcanization. The difficulty of permitting—and the cost—would be a function of the type of devulcanization technology, the processing rates, and other factors. In general, the expectation is that the cost of environmental control systems for chemical devulcanization systems would be greater than that for ultrasonic or mechanical processes. The composition of rubber and additives that are used in rubber compounds in the manufacture of vulcanized rubber can and do have a dramatic effect on the properties of materials manufactured from devulcanized rubber. Apparently, the inferior properties of some poorly (inadequately) devulcanized rubber can be compensated for by the addition of chemicals and the adjustment of operating conditions, among other remedies. In many cases in the literature, this situation is not addressed or discussed. Consequently, comparing devulcanization technologies is difficult. From most of the literature descriptions of the processes, what happens to the sulfur and other vulcanization chemicals during the various processes is unclear. Chapter 3 – Environmental Analysis Little information is available in the literature on the environmental effects associated with waste tire devulcanization technologies. The lack of information apparently exists because business developers and researchers have concentrated their efforts primarily on technology improvements and achieving satisfactory properties for devulcanized rubber, an estimation of emission rates and a detailed environmental analysis are therefore not possible. However, using data and information from some other types of tire manufacturing processes (for example, extrusion of rubber) and the characteristics of vehicle tires, a qualitative analysis was performed. The environmental analysis described subsequently is limited to chemical and ultrasonic devulcanization and assumes that control of emissions would be required. 3. 1 – Chemical technology Chemical devulcanization processes are usually batch processes that involve mixing crumb rubber with chemical reactants at a specific temperature and pressure. Once the design reaction time has elapsed, the contents are then rinsed, filtered, and dried to remove any remaining unwanted chemical components. The product can then be bagged or otherwise processed for resale. A block flow diagram of a generic chemical devulcanization process is illustrated in Figure G, showing the raw material feed is crumb rubber. The crumb rubber is mixed with one or more devulcanization agents. Chemical agents identified as devulcanization agents are listed in Table 8. During processing in the batch reactor, vapors are released that must be collected and treated before release to the ambient atmosphere. Typical types of vapors that might be emitted from a batch reactor are listed in Table 9. The chemicals that would be vented from the batch reactor are dependent on the characteristics of the waste tire feedstock and on the chemical agent(s) used in devulcanizing the crumb rubber. For example, if disulfides are used in the process, they could result in formation of hydrogen sulfide (H2S) or methyl or other mercaptans (RSH). If the chemical agent orthodichlorobenzene is used, chlorinated hydrocarbons could potentially be released in the form of air emissions. Methyl iodide is volatile, and if used as a devulcanization agent, it could be vaporized. Since tire manufacturing utilizes zinc oxide and zinc carbonate, chemical devulcanization might also produce airborne metal particulates. Once the batch is fully processed, the reactor is vented. The vent gases are treated prior to release to the atmosphere. The vapors cannot be treated by vapor phase carbon because these chemicals will plate out and blind the carbon, making it ineffective. Instead, the vapor from the batch reactor needs to be thermally oxidized. At the high exit temperatures, typically as high as 2000 °F (1100 °C), the thermal oxidizer vent gases need to be cooled in a quench tower to approximately 300 °F (150 °C). Then, to remove any metals or other particulate, the vent gases are piped to a baghouse. Because of the high thermal oxidizer temperatures, methyl mercaptans (RSH) or hydrogen sulfide (H2S) from the crumb rubber is oxidized to sulfur dioxide (SO2). Therefore, downstream of the baghouse, a scrubber is required to remove sulfur dioxide (SO2), as shown in Figure G. Scrubbed vent gases are then released to the atmosphere. In addition to the scrubber vent gases described above, liquid waste is generated from the scrubber. This liquid stream contains sodium sulfate (Na2SO4). This liquid waste can be disposed in receiving waters such as a river, stream, or bay. However, discharging to receiving waters will require a significant amount of treatment equipment and eventually a permit. As seen in Figure G, the devulcanized rubber is moved from the batch reactor to a separator by a heated extruder. Liquid that drips off the devulcanized rubber is removed in the separator and eliminated by feeding it to the same thermal oxidizer as the vent gases from the batch reactor. After the liquid has dripped off the devulcanized rubber in the separator, any remaining moisture is removed in the dryer. Fired dryers are typically fueled by natural gas burners. Dryer vent gases are piped to the common thermal oxidizer. Based on the concentration of solids in the scrubber effluent, processing the scrubber effluent through a filter press to dewater the solids may be necessary and cost-effective. Filter-pressed dewatered solids are called â€Å"filter cake. Filter cake might require disposal in a hazardous waste site. Even though the waste disposal site may accept the scrubber effluent water, the economics may favor installation and use of a filter press. This is necessary to dewater the solids due to the high cost of disposal of liquid waste. Figure G. Block Flow Diagram of a Chemical Devulcan ization System Solids H2O Batch Reactor Heated Extruder Separator Crumb Rubber Devulcanization Agent 300 ° F Liquids Devulcanized Rubber Dryer Natural Gas Vapors Thermal Oxidizer Quench Tower Baghouse Natural Gas Scrubber 2000 ° F 300 ° F H2O Air Emissions Air Emissions to Atmosphere Effluent Water Table 7. Tire Raw Materials Polymers Antiozonants Natural Rubber (polyisoprene) 2,2,4-trimethyl-1,2-dihydroquinoline (polymer) Styrene-Butadiene Rubber (SBR) n,n-(1,3-dimethylbutyl)-pphenylenediamine cis-Polybutadiene copolymer paraffinic wax Vulcanizing Agents Antioxidants Sulfur Alkylphenols Tetra-methyl thiurame sulfide Resorcinol Accelerators 2,6-Diterbutylhydroquinone Diphenylguanidine Retarders 2-Mercaptobenzothiazole n-Cyclohexylthiophthalimide n-Cyclohexyl-2-benzothiazolylsulfenamide Plasticizers 2-(n-Morpholinyl)-mercaptobenzothiazole Aliphatic oil Hexamethylenetetramine Aromatic oil Activators Naphthenic oil Zinc oxide Di-(2-ethylhexyl)-phthalate Zinc carbonate Extenders Stearic acid Silica gel Carbon black Table 8. Chemical Agents Used in Chemical Tire Devulcanization Processes Triphenyl phosphine Sodium di-n-butyl phosphite Thiol-amine reagents (specifically propane-thiol/piperidine, dithiothreitol, and hexane-lthiol) Lithium aluminum hydride Phenyl lithium Methyl iodide Hydroxide with quaternary ammonium chloride as a catalyst Orthodichlorobenzene Diphenyldisulphide Diallyl disulfide Toluene, naphtha, benzene, and/or cyclohexane, etc. in the presence of sodium Diamly disulfide Dibenzyl disulfide Diphenyl disulfide Bis(alkoxy aryl) disulfides Butyl mercaptan and thiopenols Xylene thiols Phenol sulfides and disulfides Alkyl phenol sulfides (for SBR) N,N-dialkyl aryl amine sulfides (for SBR in neutral or alkaline solutions) 3. 2 – Ultrasonic technology Devulcanization by ultrasonic methods may be a continuous process (see Figure H). As the figure illustrates, crumb rubber is loaded into a hopper and is subsequently fed into an extruder. The extruder mechanically pushes and pulls the rubber. This mechanical action serves to heat the rubber particles and soften the rubber. As the softened rubber is transported through the extruder cavity, the rubber is exposed to ultrasonic energy. The resulting combination of ultrasonic energy, along with the heat, pressure, and mechanical mastication, is sufficient to achieve varying degrees of devulcanization. The exposure time to the ultrasonic energy is only seconds. Essentially all of the rubber entering the process is discharged from the extruder in a semi-solid product stream. Process losses would be primarily emissions of fine particulate or of gases, if any, resulting from the mechanical and thermal applications occurring during devulcanization. Since the typical operating temperature of an ultrasonic devulcanization reactor is about 230 °F (110 °C), less vapor emission would be expected than from chemical devulcanization. Furthermore, since no chemicals are added to break the sulfur bonds that caused vulcanization to occur, there would likely be lower air emissions. After exiting through the extruder die, the rubber is passed through a cooling bath and then dried. Vented vapors would need to be treated by one of two methods. One method would be to use a small thermal oxidizer. The design of the thermal oxidizer, baghouse, and scrubber would be similar to that described previously for chemical devulcanization. However, the physical size of the oxidizer would be smaller, and the baghouse and scrubber would be larger. A second method to treat the vent gases exiting the ultrasonic devulcanization reactor would be use of vapor phase carbon. In this method, due to the lower operating temperatures of the ultrasonic process, vent gas exiting the ultrasonic zone would have to be heated above the dew point temperature. If this elevation in temperature is not accomplished, the vent gases could condense on the surface of the carbon and thus blind the bed. In other words, adsorption sites on the surface of the carbon would be ineffective, and vent gases would exit the carbon bed untreated. If vapor phase carbon were to be used, the capital cost would be less than that of a thermal oxidizer. However, carbon is not very efficient. Weight loading can be approximately 10 weight percent—in other words, adsorbing ten pounds of vent gas contaminants for every 100 pounds of carbon used. Use of carbon will have a relatively high operating cost. Also, the disposal of spent carbon can be very expensive. This is especially true if the spent carbon requires disposal at a hazardous waste disposal site. Even if the carbon is regenerated on-site, adsorption efficiency decreases after each regeneration. Typically, carbon can only be regenerated ten times. For illustration purposes, Figure H indicates the use of vapor phase carbon. Devulcanized rubber exiting the ultrasonic processing zone has to be cooled. A common method of reducing the rubber temperature is a cooling bath. The volume of cooling water used would be significant. Cooling water may become ontaminated from the process; this effluent water leaving the cooling bath has to be treated. If an air cooler such as fin fans is used in lieu of water in the cooling bath, the volume of effluent liquid would be reduced. Another alternative would be to use a closed-loop cooling system, where the cooling water is cooled and returned to the process for reuse. If there is a buildup of contaminants, a small slipstream could be taken off and treated in a POTW, greatly reducing the amount of effluent that would otherwise require treatment. Figure H. Block Flow Diagram of an Ultrasonic Devulcanization System Ultrasonic Processing Zone Cooling Bath Devulcanized Rubber Feed Hopper Extruder Crumb Rubber Cooling Water Supply Effluent Water Heater Air Emissions Baghouse Carbon Air Emissions to Atmosphere Table 9. Potential Types of Chemical Compounds Emitted by Chemical and Ultrasonic Devulcanization Technologies Compound Probable Source Benzene Plasticizers: Aromatic oil Methylcyclohexane Plasticizers: Na phthemic oil Toluene Plasticizers: Aromatic oil Heptane Plasticizers: Aliphatic oil 4-Vinylcyclohexene Polymers: Natural Rubber (polyisoprene), styrene-butadiene rubber (SBR), cis- Polybutadiene Ethylbenzene Plasticizers: Aromatic oil Octane Plasticizers: Aliphatic oil p-Xylene Plasticizers: Aromatic oil Styrene Polymers: styrene-butadiene rubber (SBR) Nonane Plasticizers: Aliphatic oil 1,4-Cyclohexadiene-1-isopropyl-4- methyl Polymers: Natural Rubber (polyisoprene) Isopropylbenzene Plasticizers: Aromatic oil Cyclohexene-1-methyl-3-(1- methylvinyl) Polymers: Natural Rubber (polyisoprene) Propylbenzene Plasticizers: Aromatic oil Benzaldehyde Polymers: styrene-butadiene rubber (SBR) 1-isopropyl-4-methylcyclohexane (trans) Plasticizers: Naphthemic oil 1-isopropyl-4-methylcyclohexane cis) Plasticizers: Naphthemic oil 1-isopropyl-3-methylcyclohexane Plasticizers: Naphthemic oil Decane Plasticizers: Aliphatic oil Tri-isobutylene Polymers: styrene-butadiene rubber (SBR) cis-Polybutadiene; Plasticizers: Naphthemic oil Cyclohexene-5-methyl-3-(1- methylvinyl) Polymers: Natural Rubber (polyisoprene) Indane Plasticizers: Naphthemic oil 1-Isopropyl-4-methylbenzene Plasticizers: Aromatic oil Cyclohexene-1-methyl-4-(1- methylvinyl) Polymers: Natural Rubber (polyisoprene) 1-Isopropyl-2-methylbenzene Plasticizers: Aromatic oil Dimethylstyrene Polymers: styrene-butadiene rubber (SBR) Undecane Plasticizers: Aliphatic oil Tetramethylbenzene Plasticizers: Aromatic oil 1,2,3,4-Tetrahydronaphthalene Plasticizers: Naphthemic oil 1,3-Di-isopropyl benzene Plasticizers: Aromatic oil 1,4-Di-isopropyl benzene Plasticizers: Aromatic oil Compound Probable Source 2-Isopropyl-6-methylphenol Antioxidents: Alkylphenols Cyclohexylisothiocyanate Retarders: n-Cyclohexyl-thiophthalimide Cyclododecatriene Polymers: cis-Polybutadiene Dodecane Plasticizers: Aliphatic oil Tridecane Plasticizers: Aliphatic oil Tetraisobutylene Polymers: styrene-butadiene rubber (SBR) cis-Polybutadiene; Plasticizers: Naphthemic oil -ter-Butylstyrene Polymers: styrene-butadiene rubber (SBR) Dimethylpropylhexahydronaphthale ne Plasticizers: Naphthemic oil Tetradecane Plasticizers: Aliphatic oil Nonylbenzene Plasticizers: Aromatic oil 2,6-Di-ter-butyl-p-quinone Antioxidents: 2,6-Diterbutyl-hydroquinone Pentadecane Plasticizers: Aliphatic oil 1,6-dimethyl-4-isopropyl-1,2,3,4- tetra-hydronaphthalene Plasticize rs: Naphthemic oil Decylbenzene Plasticizers: Aromatic oil Di-ter-butylthiophene Plasticizers: Aromatic oil Diethyl phthalate Plasticizers: Di-(2-ethylhexyl)-phthalate Hexadecane Plasticizers: Aliphatic oil ,2-Di-tolylethane Polymers: styrene-butadiene rubber (SBR) Heptadecane Plasticizers: Aliphatic oil 2,6-Di-ter-butyl-4-ethylphenol Antioxidents: Alkylphenols Octadecane Plasticizers: Aliphatic oil 1-Phenylnaphthalene Plasticizers: Aromatic oil Di-iso-butyl phthalate Plasticizers: Di-(2-ethylhexyl)-phthalate Tridecylbenzene Plasticizers: Aromatic oil Dibutyl phthalate Plasticizers: Di-(2-ethylhexyl)-phthalate Eicosane Plasticizers: Aliphatic oil Heneicosane Plasticizers: Aliphatic oil Docosane Plasticizers: Aliphatic oil Di-(2-ethylhexyl) phthalate Plasticizers: Di-(2-ethylhexyl)-phthalate Chapter 4 – Conclusions Devulcanization of specific types of rubber and/or waste tire rubber has a long history. However, only recently have limited technical data been reported in the available literature. Usually when reported, the tested properties of devulcanized rubber compose an incomplete list. This is especially true in the interpretation of how the devulcanized product would perform during compounding, in the manufactured end product, or both. Circumstantial and anecdotal evidence indicates significant technical and economic barriers to devulcanization of waste rubber. Based on the information collected in the study, is believed that the only method of achieving bulk devulcanization, as opposed to surface devulcanization, rests with ultrasonic or microwave devulcanization methods. Of these two methods of energy application, ultrasound appears to have substantially more research and development history. An important observation is that microwave technology is not an effective or efficient way to devulcanize non-polar rubber types, which collectively compose the vast majority of the mass of rubber in waste rubbers. Because of the ability to internally devulcanize cured rubber, ultrasonically devulcanized waste tire rubber may have more desirable marketing characteristics than those of surface-devulcanizing processes under similar conditions of cost and yield. The latter processes (surface devulcanizing) include mechanical, chemical, and biological processes. However, test data and applications for ultrasonically devulcanized waste rubber are lacking in the industry, along with process cost documentation. The devulcanized rubber market is most fully developed for single product materials made from manufacturing scrap that are reclaimed for reuse in the same process or in a broader specification application. The reprocessing of single rubbers depends upon being located near a large-volume rubber products company with enough scrap and enough rubber applications to justify the devulcanization step. Devulcanization of waste rubber, despite considerable research and developmental effort, is still in an early growth stage. Devulcanization lacks adequate test data and data interpretation, and it has poorly defined end product specifications without adequately justified and defined applications and uses. Research funds appear to be most available for studying devulcanization of single rubber types, as opposed to studying rubber types with complex mixtur. In applications already using crumb rubber, devulcanized rubber can have advantages if the process combines a vulcanized rubber or other compatible material to create an integrated structure. The structure must have much better properties than those imparted by the filler role that crumb rubber frequently serves. 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Nutrition and Aging free essay sample

This article covers some reasons of eating healthy as we age due to changes occurring slowly over time in all the body systems. These changes are influenced by life events, illnesses, genetic traits and socioeconomic factors. It is noted, while we age, we lose lean body mass. This reduced muscle mass includes skeletal muscle, smooth muscle and muscle that slow down vital organ function, with loss of cardiac muscle perhaps the most critical. Cardiac capacity can be reduced and cardiac function impaired by chronic diseases such as hypertension or diabetes. Changes also occur in the kidneys, lungs and liver, and hamper the bodies’ ability to generate new protein tissue. Plus, aging can slow the immune systems response in making antibodies furthermore, loss of lean body mass also means reduced body water for 72 percent of total body water is in lean muscle tissue. Accordingly, while we age, body fat increases more so from consuming too many calories. We will write a custom essay sample on Nutrition and Aging or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Nutrition can be a factor in all of the changes noted above. However, the slowing of the normal action of the digestive tract plus general changes have the most direct effect on nutrition. Digestive secretions diminish, although enzymes remain adequate. Adequate dietary fiber, as opposed to increased use of laxatives, will maintain regular bowel function and not interfere with the digestion and absorption of nutrients, which is what often occurs with laxative use or abuse. Calorie needs change due to more body fat and less lean muscle. Less activity can further decrease calorie needs. The challenge for the elderly is to meet the same nutrient needs as when they were younger, yet consume fewer calories. The answer to this problem is to choose foods high in nutrients in relation to their calories. Such foods are considered nutrient-dense. For example, low-fat milk is more nutrient dense than regular milk. Its nutrient content is the same, but it has fewer calories because it has less fat. It also becomes more important that diets contain enough calcium, fiber, iron, protein, and the vitamins A, C, D and that supplements are added if they are not consuming enough from their regular diet. As we age, water is still quite necessary, even though it appears we are drying up from the inside out, we need to drink plenty of liquids throughout the day,