Thursday, October 31, 2019

This is an Assignment where you have to analyze an Annual Report, do Essay - 1

This is an Assignment where you have to analyze an Annual Report, do some calculations and write a report about your findings (Accounting) - Essay Example e financial year of 2004, the company presents an acceptable profitability performance, acceptable solvability ratios, good efficiency performance and a rather unpreferable liquidity performance. We believe that management is able to maintain stability of the business. Shareholder should give good evaluation points to the management and their performance, but nevertheless, should also be aware of the nature of the industry which present the possibility of only providing the corporation with no more than 3% profit (out of sales). There are several important emphasizes relating to the significance of financial reporting. We already know that the main purpose of providing sound and viable financial report is to satisfy current shareholders and investors, and attract future ones. But what are the significant points that drive shareholders and investors to finalize their financial investment decisions? According to Financial Management (2005), investors seldom read trough business plans or financial statements thoroughly. They already know what they want. According to the article, most investors want to see business that will grow rapidly and someday will provide a handsome profit. Investors generally does not invest on products, instead, they invest on business. Thus, long term investors generally want to see good profitability ratios and prospects, more than other indicators within financial reports. Joseph Stiglitz (2002), on the other hand, stated that only 10% of today’s new capitals has been raised via equity markets. This condition rises because shareholders do not generally have enough access to corporations to ensure themselves that their investments are safe and growing. For major shareholders (present and future ones), the most influential factor in terms of investment is risk. Future shareholders are generally reluctant to finance businesses that present considerably significant or uncertain risks. They have also been wanting to have more ‘control’

Tuesday, October 29, 2019

Video Game Effect Essay Example for Free

Video Game Effect Essay There are millions of people who play highly controversial games like Grand Theft Auto and other violence video games, realize that it is a game and do not do things they do in the game in real life. If people believe that video games cause behavior problems, they are underlying issues with the gamer himself, and not with the software, but according to American Psychological Association, almost ninety percent of kids between the ages eight and sixteen are addicted to video game especially the violent one. The average girls spends almost six to eight hour week’s playing video games which does not sound bad comparing to boys who spends an average of thirteen hours a week. Some parents reported that video games only describe virtual reality, and should not translate into real world problem. However, children are more likely to imitate the actions of a character with which they classify themselves with. In all violent video games, players are often required to take point of view of the shooter or perpetrator, which show a change of their behavior. Study shows that repetition increases learning and video games required repetition in order to master control characters movement. If the game is violent, then the effect is a behavioral practice for a violent activity. These children who are involve in playing violent video games are more aggressive than who are not involve with these game, which at some point of their life, they will get heart or might die because of their action. Recently, parents become unaware with their kids behavior in real life. Some of them let their kids do whatever they like to do like playing violent video games for long hours or watching brutal shows on television. Report by American Psychological Association â€Å"disagree that violent video games cause behavior problems, because the choices people make cause violent behavior. Video games, even the violent once, can be good experience. † But parents need to teach their kids those video games need to be separate from reality. The choices they make in their daily life have absolutely nothing to do with video games. In fact they may be able to take out any aggressions that they have on a video game, rather than go out and beat someone up, that what their parents believe, but what they do not know is playing video game frequently for long hours has a huge negative on kids because it feed their brain with aggression, violence, and fighting which creates problems such as poor social skills from kids to their parents and the outside world. Sociology studies shows that boys by the age of twenty-one had spend more than 10000 hours or more just by playing video games American Psychological Association wrote â€Å"97% between the age 12 to 17 in the US played video game†¦ top 10 out of 20 were violent. † USA today made study twenty years ago about sixty percent of American family had sat down as family dinners, same study last year the number drop down to twenty percent. Because kids are spending their times on video game, it creates huge problems such as poor social skills, poor grade in school, and live in hostile environment. Psychologist concludes, that video game is nature requirement activities, because it based on reward system and as human we try to be satisfied and achieved all requirements. For example, in video game Mafia 2, the character is required to rob bank which is the basic objective. But if the player kills all securities without triggering the alarm, the player will receive bounce. Since all players love to achieve more, they will do the mission, after completing the mission they will play it again in order to get the bounces. If parents are worried that their children are addicted to violent video game and spending so much time playing it, they should set limits, like playing video game for an hour after completing their homework, also try to encourage their children to play outside, and do other activity. Parents must check the Entertainment Software Rating Board (ESRB) to learn about the video game’s content and what age range it belongs to. Parents should strongly monitor their children about video games that they are buying, and from online games. Violent video games have been blamed for increase bullying, assaulting women, and school shooting, because violent games teach children that violence is way to solve problems and it is acceptable in this world. Studied showed that sixty percent of middle school children who played at least one video game that rated mature has hit, beat, and assault other students. Also it shows that students who committed this violence act were enjoying inflected pain and become less forgiving. For example, in Bully the character have to fight with teacher and other student in order to be popular in school. In other word, this video game encourages kids to be disrespectful to the elder and to the other student. Female in violent video games are mostly present as explore to sexual contact, like being rape, get killed, and thrown behind the bushes. What make it ironic is the player is rewarded by getting some extra feature. For example, in LA Noire the character is homicide, in one of his chapter the player must solve several of cases that women been rape, nude, murder, and thrown in dumpster or tree. In 1998 study shows that thirty percent of violent video games involve women been attacked and rape. Another example, in Grand Theft Auto, which considers one of the best seller games in 2008, player must gain money to be able to buy armor or guns so the player will target female for two reasons. First, they carry more cash, and second they weak. Schools shooting have been connected to shooting video games. Students who have been exposed to violent video games held more violent attitudes, had more hostile personalities, were less forgiveness, and believed that being sadistic with other is normal. Seung-Hui Cho the student who opened fire at Virginia Tech incident. He was addicted to shooting game called Counter Strike, the objective of that game is to kill the other team where character are allowed to buy guns, armor, and grenade. Every time the character kill member of the other team he rewarded with money. If parents and schools are affected by kids who play violent video games for long hours, it means media and society are affected too. Societies are concern with violence and media including the internet have extend worlds of video game, especially the violent one, such as the Hitman series, Grand Theft Auto, Mortal Kombat, and more. The character in video games may get away when he committed crime or brutal events. As adults they know the different between real life and fiction one, but kids do not know that. Kids might steal money or attack other kids believing they will get away. For example, in Grand Theft Auto player can steal car, run over pedestrian, and hit another car. With kind action the police well attempt to arrest you character. However, if the character were able to drive fast or hide inside building for couple of minutes police will ignore you and let you free.

Sunday, October 27, 2019

Polyisobutylene Applications

Polyisobutylene Applications Fuel and lubricant additive. Polyisobutylene (in the form of polyisobutylene succinimide) has interesting properties when used as an additive in lubricating oils and motor fuels. Polyisobutylene added in small amounts to the lubricating oils used in machining results in a significant reduction in the generation of oil mist and thus reduces the operators inhalation of oil mist.[2] It is also used to clean up waterborne oil spills as part of the commercial product Elastol. When added to crude oil it increases the oils viscoelasticity when pulled, causing the oil to resist breakup when it is vacuumed from the surface of the water. As a fuel additive, polyisobutylene has detergent properties. When added to diesel fuel, it resists fouling of fuel injectors, leading to reduced hydrocarbon and particulate emissions.[3] It is blended with other detergents and additives to make a detergent package that is added to gasoline and diesel fuel to resist buildup of deposits and engine knock.[4] Polyisobutylene is used in some formulations as a thickening agent. [edit]Sporting equipment Butyl rubber is used for the bladders in basketballs, footballs, soccer balls and other inflatable balls to provide a tough, airtight inner compartment. [edit]Roof Repair Butyl rubber sealant is used for rubber roof repair and for maintenance of roof membranes (especially around the edges). It is important to have the roof membrane fixed, as a lot of fixtures (i.e., air conditioner vents, plumbing and other pipes, etc.) can considerably loosen it. Rubber roofing typically refers to a specific type of roofing materials that are made of ethylene propylene diene monomers (EPDM). It is crucial to the integrity of such roofs to avoid using harsh abrasive materials and petroleum-based solvents for their maintenance. Polyester fabric laminated to butyl rubber binder provides a single-sided waterproof tape that can be used on metal, PVC, and cement joints. It is ideal for repairing and waterproofing metal roofs. [edit]Gas masks and chemical agent protection Butyl rubber is one of the most robust elastomers when subjected to chemical warfare agents and decontamination materials. It is a harder and less porous material than other elastomers, such as natural rubber or silicone, but still has enough elasticity to form an airtight seal. While butyl rubber will break down when exposed to agents such as NH3 (ammonia) or certain solvents, it breaks down more slowly than comparable elastomers. It is therefore used to create seals in gas masks and other protective clothing. [edit]Chewing gum Molecular structure: Rubber Chemical Structure Introduction to rubber chemical structure: In the organic chemistry section of chemistry ,we learn about the various polymers , monomers,elastomers etc.Monomer is a single unit and when huge number of monomers are combined or say polymerised then polymers are formed.The process of conversion of monomer to polymer is known as p-olymerisation.Elastomer is an another category of polymers having a specific properties of regaining of its structure even if it is stretched.Rubber comes under the category of elastomer.In general life rubber has variety of uses.the important property of rubber is that it regains its structure even if it is stretched.Stretching can be done up to a certain limit.If it is stretched beyond limit then it can break. Rubber can be found in two forms 1)Natural rubber 2)Synthetic Rubber Natural rubber is a kind of rubber which which is found directly from the nature.And when the natural rubber is processed under some chemical processes then a new kind of rubber is formed ,this rubber is known as synthetic rubber.We can also say that natural rubber are synthesised from the natural rubber.Both this rubber are of great use because of its specific features. Structure of rubber: Main composition of crude rubber is hydrocarbons.It also contains some proteins and materials which are soluble in acetone.The hydrocarbons which possess the properties of rubber are usually high in molecular weight and it ranges from 45000 to 3000000.Isoprene is a monomer of natural rubber.When huge number of isoprene units are polymerised then a polymer is formed . Cis and Trans Configuration of Rubber The cis configuration of the natural rubber is the reason for the rubber properties in it. Cis configuration means that extension of the chain is on the same side of the ethylene bond.If the configuration is trans, it means that the extension of chain is on the both sides of ethylene bond,then it is a hard plastic.In case of trans it does not show the properties of rubber. Synthetic rubber is of great use in the industry.Some of the widely used synthetic rubber are butyl rubber which is formed by the copolymerisation of isobutylene and a little amount isoprene.Another synthetic rubber is Styrene Butadiene Rubber also known as SBR.Buna N and buna S is also a kind of synthetic rubber often use in the industry. Vulcanisation of Rubber In the rubber molecules the cross linking between the chains are very less.This leads to the softness in the rubber .To make the rubber hard some chemicals are added to it.The process is known as vulcanisation.In this process the natural rubber is treated with some chemicals ,more often chemical used is sulphur.When sulphur reacts with the natural rubber then it increases the cross linking between the molecules in the rubber.It also forms many sulphide bonds.Due to formation of many new crosslinkings and many sulphide bonds the natural rubber becomes hard.Natural rubber is a kind of thermoplastic,it means that it becomes soft when it is subjected to heat and it becomes hard when it is subjected to cold. butyl rubber (IIR), also called isobutylene-isoprene rubber, a synthetic rubber produced by copolymerizing isobutylene with small amounts of isoprene. Valued for its chemical inertness, impermeability to gases, and weatherability, butyl rubber is employed in the inner linings of automobile tires and in other specialty applications. Both isobutylene (C[CH3]2=CH2) and isoprene (CH2=C[CH3]-CH=CH2) are usually obtained by the thermal cracking of natural gas or of the lighter fractions of crude oil. At normal temperature and pressure isobutylene is a gas and isoprene is a volatile liquid. For processing into IIR, isobutylene, refrigerated to very low temperatures (approximately à ¢Ã‹â€ Ã¢â‚¬â„¢100  °C [à ¢Ã‹â€ Ã¢â‚¬â„¢150  °F]), is diluted with methyl chloride. Low concentrations (1.5 to 4.5 percent) of isoprene are added in the presence of aluminum chloride, which initiates the reaction in which the two compounds copolymerize (i.e., their single-unit molecules link together to form giant, multiple-unit molecules). The polymer repeating units have the following structures: Because the base polymer, polyisobutylene, is stereoregular (i.e., its pendant groups are arranged in a regular order along the polymer chains) and because the chains crystallize rapidly on stretching, IIR containing only a small amount of isoprene is as strong as natural rubber. In addition, because the copolymer contains few unsaturated groups (represented by the carbon-carbon double bond located in each isoprene repeating unit), IIR is relatively resistant to oxidation-a process by which oxygen in the atmosphere reacts with the double bonds and breaks the polymer chains, thereby degrading the material. Butyl rubber also shows an unusually low rate of molecular motion well above the glass transition temperature (the temperature above which the molecules are no longer frozen in a rigid,glassy state). This lack of motion is reflected in the copolymers unusually low permeability to gases as well as in its outstanding resistance to attack by ozone. The copolymer is recovered from the solvent as a crumb, which can be compounded with fillers and other modifiers and then vulcanized into practical rubber products. Owing to its excellent air retention, butyl rubber is the preferred material for inner tubes in all but the largest sizes. It also plays an important part in the inner liners of tubeless tires. (Because of poor tread durability, all-butyl tires have not proved successful.) IIR is also used for many other automobile components, including window strips, because of its resistance to oxidation. Its resistance to heat has made it indispensable in tire manufacture, where it forms the bladders that retain the steam or hot water used to vulcanize tires. Bromine or chlorine can be added to the small isoprene fraction of IIR to make BIIR or CIIR (known as halobutyls). The properties of these polymers are similar to those of IIR, but they can be cured more rapidly and with different and smaller amounts of curative agents. As a result, BIIR and CIIR can be cocured more readily in contact with other elastomers making up a rubber product. Butyl rubber was first produced by American chemists William Sparks and Robert Thomas at the Standard Oil Company of New Jersey (nowExxon Corporation) in 1937. Earlier attempts to produce synthetic rubbers had involved the polymerization of dienes (hydrocarbon molecules containing two carbon-carbon double bonds) such as isoprene and butadiene. Sparks and Thomas defied convention by copolymerizing isobutylene, an olefin (hydrocarbon molecules containing only one carbon-carbon double bond) with small amounts-e.g., less than 2 percent-of isoprene. As a diene, isoprene provided the extra double bond required to cross-link the otherwise inert polymer chains, which were essentially polyisobutylene. Before experimental difficulties were resolved, butyl rubber was called futile butyl, but with improvements it enjoyed wide acceptance for its low permeability to gases and its excellent resistance to oxygen and ozone at normal temperatures. During World War IIthe copolymer was called GR-I, for Government Rubber-Isobutylene. LINKS Related Articles Top of Form Polymers 1. Introduction Prior to the early 1920s, chemists doubted the existence of molecules having molecular weights greater than a few thousand. This limiting view was challenged by Hermann Staudinger, a German chemist with experience in studying natural compounds such as rubber and cellulose. In contrast to the prevailing rationalization of these substances as aggregates of small molecules, Staudinger proposed they were made up of macromolecules composed of 10,000 or more atoms. He formulated a polymeric structure for rubber, based on a repeating isoprene unit (referred to as a monomer). For his contributions to chemistry, Staudinger received the 1953 Nobel Prize. The terms polymer and monomer were derived from the Greek roots poly (many), mono (one) and meros (part). Recognition that polymeric macromolecules make up many important natural materials was followed by the creation of synthetic analogs having a variety of properties. Indeed, applications of these materials as fibers, flexible films, adhesives, resistant paints and tough but light solids have transformed modern society. Some important examples of these substances are discussed in the following sections. art 2. Writing Formulas for Polymeric Macromolecules The repeating structural unit of most simple polymers not only reflects the monomer(s) from which the polymers are constructed, but also provides a concise means for drawing structures to represent these macromolecules. For polyethylene, arguably the simplest polymer, this is demonstrated by the following equation. Here ethylene (ethene) is the monomer, and the corresponding linear polymer is called high-density polyethylene (HDPE). HDPE is composed of macromolecules in which n ranges from 10,000 to 100,000 (molecular weight 2*105 to 3 *106 ). If Y and Z represent moles of monomer and polymer respectively, Z is approximately 10-5 Y. This polymer is called polyethylene rather than polymethylene, (-CH2-)n, because ethylene is a stable compound (methylene is not), and it also serves as the synthetic precursor of the polymer. The two open bonds remaining at the ends of the long chain of carbons (colored magenta) are normally not specified, because the atoms or groups found there depend on the chemical process used for polymerization. The synthetic methods used to prepare this and other polymers will be described later in this chapter. Unlike simpler pure compounds, most polymers are not composed of identical molecules. The HDPE molecules, for example, are all long carbon chains, but the lengths may vary by thousands of monomer units. Because of this, polymer molecular weights are usually given as averages. Two experimentally determined values are common: Mn , the number average molecular weight, is calculated from the mole fraction distribution of different sized molecules in a sample, and Mw , the weight average molecular weight, is calculated from the weight fraction distribution of different sized molecules. These are defined below. Since larger molecules in a sample weigh more than smaller molecules, the weight average Mw is necessarily skewed to higher values, and is always greater than Mn. As the weight dispersion of molecules in a sample narrows, Mw approaches Mn, and in the unlikely case that all the polymer molecules have identical weights (a pure mono-disperse sample), the ratio Mw / Mn becomes unity. The influence of different mass distributions on Mn and Mw may be examined with the aid of a simple mass calculator. To use this device Click Here. Many polymeric materials having chain-like structures similar to polyethylene are known. Polymers formed by a straightforward linking together of monomer units, with no loss or gain of material, are called addition polymers or chain-growth polymers. A listing of some important addition polymers and their monomer precursors is presented in the following table. Some Common Addition Polymers Name(s) Formula Monomer Properties Uses Polyethylene low density (LDPE) -(CH2-CH2)n- ethylene CH2=CH2 soft, waxy solid film wrap, plastic bags Polyethylene high density (HDPE) -(CH2-CH2)n- ethylene CH2=CH2 rigid, translucent solid electrical insulation bottles, toys Polypropylene (PP) different grades -[CH2-CH(CH3)]n- propylene CH2=CHCH3 atactic: soft, elastic solid isotactic: hard, strong solid similar to LDPE carpet, upholstery Poly(vinyl chloride) (PVC) -(CH2-CHCl)n- vinyl chloride CH2=CHCl strong rigid solid pipes, siding, flooring Poly(vinylidene chloride) (Saran A) -(CH2-CCl2)n- vinylidene chloride CH2=CCl2 dense, high-melting solid seat covers, films Polystyrene (PS) -[CH2-CH(C6H5)]n- styrene CH2=CHC6H5 hard, rigid, clear solid soluble in organic solvents toys, cabinets packaging (foamed) Polyacrylonitrile (PAN, Orlon, Acrilan) -(CH2-CHCN)n- acrylonitrile CH2=CHCN high-melting solid soluble in organic solvents rugs, blankets clothing Polytetrafluoroethylene (PTFE, Teflon) -(CF2-CF2)n- tetrafluoroethylene CF2=CF2 resistant, smooth solid non-stick surfaces electrical insulation Poly(methyl methacrylate) (PMMA, Lucite, Plexiglas) -[CH2-C(CH3)CO2CH3]n- methyl methacrylate CH2=C(CH3)CO2CH3 hard, transparent solid lighting covers, signs skylights Poly(vinyl acetate) (PVAc) -(CH2-CHOCOCH3)n- vinyl acetate CH2=CHOCOCH3 soft, sticky solid latex paints, adhesives cis-Polyisoprene natural rubber -[CH2-CH=C(CH3)-CH2]n- isoprene CH2=CH-C(CH3)=CH2 soft, sticky solid requires vulcanization for practical use Polychloroprene (cis + trans) (Neoprene) -[CH2-CH=CCl-CH2]n- chloroprene CH2=CH-CCl=CH2 tough, rubbery solid synthetic rubber oil resistant 3. Properties of Macromolecules A comparison of the properties of polyethylene (both LDPE HDPE) with the natural polymers rubber and cellulose is instructive. As noted above, synthetic HDPE macromolecules have masses ranging from 105 to 106 amu (LDPE molecules are more than a hundred times smaller). Rubber and cellulose molecules have similar mass ranges, but fewer monomer units because of the monomers larger size. The physical properties of these three polymeric substances differ from each other, and of course from their monomers. à ¢Ã¢â€š ¬Ã‚ ¢ HDPE is a rigid translucent solid which softens on heating above 100 ° C, and can be fashioned into various forms including films. It is not as easily stretched and deformed as is LDPE. HDPE is insoluble in water and most organic solvents, although some swelling may occur on immersion in the latter. HDPE is an excellent electrical insulator. à ¢Ã¢â€š ¬Ã‚ ¢ LDPE is a soft translucent solid which deforms badly above 75 ° C. Films made from LDPE stretch easily and are commonly used for wrapping. LDPE is insoluble in water, but softens and swells on exposure to hydrocarbon solvents. Both LDPE and HDPE become brittle at very low temperatures (below -80 ° C). Ethylene, the common monomer for these polymers, is a low boiling (-104 ° C) gas. à ¢Ã¢â€š ¬Ã‚ ¢ Natural (latex) rubber is an opaque, soft, easily deformable solid that becomes sticky when heated (above. 60 ° C), and brittle when cooled below -50 ° C. It swells to more than double its size in nonpolar organic solvents like toluene, eventually dissolving, but is impermeable to water. The C5H8 monomer isoprene is a volatile liquid (b.p. 34 ° C). à ¢Ã¢â€š ¬Ã‚ ¢ Pure cellulose, in the form of cotton, is a soft flexible fiber, essentially unchanged by variations in temperature ranging from -70 to 80 ° C. Cotton absorbs water readily, but is unaffected by immersion in toluene or most other organic solvents. Cellulose fibers may be bent and twisted, but do not stretch much before breaking. The monomer of cellulose is the C6H12O6aldohexose D-glucose. Glucose is a water soluble solid melting below 150 ° C. To account for the differences noted here we need to consider the nature of the aggregate macromolecular structure, or morphology, of each substance. Because polymer molecules are so large, they generally pack together in a non-uniform fashion, with ordered or crystalline-like regions mixed together with disordered or amorphous domains. In some cases the entire solid may be amorphous, composed entirely of coiled and tangled macromolecular chains. Crystallinity occurs when linear polymer chains are structurally oriented in a uniform three-dimensional matrix. In the diagram on the right, crystalline domains are colored blue. Increased crystallinity is associated with an increase in rigidity, tensile strength and opacity (due to light scattering). Amorphous polymers are usually less rigid, weaker and more easily deformed. They are often transparent. Three factors that influence the degree of crystallinity are: i) Chain length ii) Chain branching iii) Interchain bonding The importance of the first two factors is nicely illustrated by the differences between LDPE and HDPE. As noted earlier, HDPE is composed of very long unbranched hydrocarbon chains. These pack together easily in crystalline domains that alternate with amorphous segments, and the resulting material, while relatively strong and stiff, retains a degree of flexibility. In contrast, LDPE is composed of smaller and more highly branched chains which do not easily adopt crystalline structures. This material is therefore softer, weaker, less dense and more easily deformed than HDPE. As a rule, mechanical properties such as ductility, tensile strength, and hardness rise and eventually level off with increasing chain length. The nature of cellulose supports the above analysis and demonstrates the importance of the third factor (iii). To begin with, cellulose chains easily adopt a stable rod-like conformation. These molecules align themselves side by side into fibers that are stabilized by inter-chain hydrogen bonding between the three hydroxyl groups on each monomer unit. Consequently, crystallinity is high and the cellulose molecules do not move or slip relative to each other. The high concentration of hydroxyl groups also accounts for the facile absorption of water that is characteristic of cotton. Natural rubber is a completely amorphous polymer. Unfortunately, the potentially useful properties of raw latex rubber are limited by temperature dependence; however, these properties can be modified by chemical change. The cis-double bonds in the hydrocarbon chain provide planar segments that stiffen, but do not straighten the chain. If these rigid segments are completely removed by hydrogenation (H2 Pt catalyst), the chains lose all constrainment, and the product is a low melting paraffin-like semisolid of little value. If instead, the chains of rubber molecules are slightly cross-linked by sulfur atoms, a process called vulcanization which was discovered by Charles Goodyear in 1839, the desirable elastomeric properties of rubber are substantially improved. At 2 to 3% crosslinking a useful soft rubber, that no longer suffers stickiness and brittleness problems on heating and cooling, is obtained. At 25 to 35% crosslinking a rigid hard rubber product is formed. The following illust ration shows a cross-linked section of amorphous rubber. By clicking on the diagram it will change to a display of the corresponding stretched section. The more highly-ordered chains in the stretched conformation are entropically unstable and return to their original coiled state when allowed to relax (click a second time). On heating or cooling most polymers undergo thermal transitions that provide insight into their morphology. These are defined as the melt transition, Tm , and the glass transition, Tg . Tm is the temperature at which crystalline domains lose their structure, or melt. As crystallinity increases, so does Tm. Tg is the temperature below which amorphous domains lose the structural mobility of the polymer chains and become rigid glasses. Tg often depends on the history of the sample, particularly previous heat treatment, mechanical manipulation and annealing. It is sometimes interpreted as the temperature above which significant portions of polymer chains are able to slide past each other in response to an applied force. The introduction of relatively large and stiff substituents (such as benzene rings) will interfere with this chain movement, thus increasing Tg (note polystyrene below). The introduction of small molecular compounds called plasticizers into the polymer matrix increases the interchain spacing, allowing chain movement at lower temperatures. with a resulting decrease in Tg. The outgassing of plasticizers used to modify interior plastic components of automobiles produces the new-car smell to which we are accustomed. Tm and Tg values for some common addition polymers are listed below. Note that cellulose has neither a Tm nor a Tg. Polymer LDPE HDPE PP PVC PS PAN PTFE PMMA Rubber Tm ( °C) 110 130 175 180 175 >200 330 180 30 Tg ( °C) _110 _100 _10 80 90 95 _110 105 _70 Rubber is a member of an important group of polymers called elastomers. Elastomers are amorphous polymers that have the ability to stretch and then return to their original shape at temperatures above Tg. This property is important in applications such as gaskets and O-rings, so the development of synthetic elastomers that can function under harsh or demanding conditions remains a practical goal. At temperatures below Tg elastomers become rigid glassy solids and lose all elasticity. A tragic example of this caused the space shuttle Challenger disaster. The heat and chemical resistant O-rings used to seal sections of the solid booster rockets had an unfortunately high Tg near 0  °C. The unexpectedly low temperatures on the morning of the launch were below this Tg, allowing hot rocket gases to escape the seals. Copolymers The synthesis of macromolecules composed of more than one monomeric repeating unit has been explored as a means of controlling the properties of the resulting material. In this respect, it is useful to distinguish several ways in which different monomeric units might be incorporated in a polymeric molecule. The following examples refer to a two component system, in which one monomer is designated A and the other B. Statistical Copolymers Also called random copolymers. Here the monomeric units are distributed randomly, and sometimes unevenly, in the polymer chain: ~ABBAAABAABBBABAABA~. Alternating Copolymers Here the monomeric units are distributed in a regular alternating fashion, with nearly equimolar amounts of each in the chain: ~ABABABABABABABAB~. Block Copolymers Instead of a mixed distribution of monomeric units, a long sequence or block of one monomer is joined to a block of the second monomer: ~AAAAA-BBBBBBB~AAAAAAA~BBB~. Graft Copolymers As the name suggests, side chains of a given monomer are attached to the main chain of the second monomer: ~AAAAAAA(BBBBBBB~)AAAAAAA(BBBB~)AAA~. 1. Addition Copolymerization Most direct copolymerizations of equimolar mixtures of different monomers give statistical copolymers, or if one monomer is much more reactive a nearly homopolymer of that monomer. The copolymerization of styrene with methyl methacrylate, for example, proceeds differently depending on the mechanism. Radical polymerization gives a statistical copolymer. However, the product of cationic polymerization is largely polystyrene, and anionic polymerization favors formation of poly(methyl methacrylate). In cases where the relative reactivities are different, the copolymer composition can sometimes be controlled by continuous introduction of a biased mixture of monomers into the reaction. Formation of alternating copolymers is favored when the monomers have different polar substituents (e.g. one electron withdrawing and the other electron donating), and both have similar reactivities toward radicals. For example, styrene and acrylonitrile copolymerize in a largely alternating fashion. Some Useful Copolymers Monomer A Monomer B Copolymer Uses H2C=CHCl H2C=CCl2 Saran films fibers H2C=CHC6H5 H2C=C-CH=CH2 SBR styrene butadiene rubber tires H2C=CHCN H2C=C-CH=CH2 Nitrile Rubber adhesives hoses H2C=C(CH3)2 H2C=C-CH=CH2 Butyl Rubber inner tubes F2C=CF(CF3) H2C=CHF Viton gaskets A terpolymer of acrylonitrile, butadiene and styrene, called ABS rubber, is used for high-impact containers, pipes and gaskets. For polyisobutylene at a glance, click here! Polyisobutylene is a synthetic rubber, or elastomer. Its special because its the only rubber thats gas impermeable, that is, its the only rubber that can hold air for long periods of time. You may have noticed that balloons will go flat after a few days. This is because they are made of polyisoprene, which is not gas impermeable. Because polyisobutylene will hold air, it is used to make things like the inner liner of tires, and the inner liners of basketballs. Polyisobutylene, sometimes called butyl rubber, and other times PIB, is a vinyl polymer. Its very similar to polyethylene and polypropylene in structure, except that every other carbon is substituted with two methyl groups. It is made from the monomer isobutylene, by cationic vinyl polymerization. And this is that monomer isobutylene: Usually, a small amount of isoprene is added to the isobutylene. The polymerization is carried out at a right frosty -100 oC, or -148 oF for you Americans out there. This is because the reaction is so fast we cant control it unless we freeze it colder than a brass toilet seat in the Yukon. Polyisobutylene was first developed during the early 1940s. At that time, the most widely used rubber was natural rubber, polyisoprene. Polyisoprene was an excellent elastomer, and easy to isolate from the sap of the hevea tree. Huge plantations thrived in Malaysia and grew hevea trees to supply the worlds rubber needs. There was only one slight problem, and that was that Malaysia had just been conquered by the Imperial Japanese Army, and wouldnt you know we just so happened to be fighting the Second World War against them right at that moment. Before the war was over more than sixty million people would be dead. Deprived of natural rubber, the Allied nations did some quick thinking and came up with PIB. It obviously worked, because the Allies won the war. Ok, we didnt actually invent polyisobutylene during the war. It had been invented long before the war by chemists in Germany. Theres irony! But it wasnt very useful until American chemists came up with a way to crosslink it. What they did was to copolymerize isobutylene with a little bit, say, around one percent, isoprene. This is isoprene: When isoprene is polymerized with the isobutylene we get a polymer that looks like this: About one or two out of every hundred repeat units is an isoprene unit, shown in blue. These have double bonds, which means the polymer can be crosslinked byvulcanization just like natural rubber. What is this vulcanization? To find out, click here. Stealing Vulcans Fire There was a time long past when the only rubber we had was natural rubber latex, polyisoprene. Straight out of the tree, natural rubber latex isnt good for much. It gets runny and sticky when it gets warm, and it gets hard and brittle when its cold. Tires made out of it wouldnt be much good unless one lived in some happy land where the temperature was seventy degrees year round. A long time agohow long, you ask? It was about a hundred and sixty years ago, 1839 to be exact. This was before there were any cars to need tires, but the idea of a useable rubber was still attractive. One person trying to make rubber more useful was named Charles Goodyear, a tinkerer and inventor, and by no means a successful one at this point. While goofing around in his kitchen with a piece of fabric coated with a m

Friday, October 25, 2019

GCSE English Coursework: The Crucible Essay -- Essay on The Crucible

GCSE English Coursework: The Crucible The Crucible. Arthur Miller, ‘The Crucible’ is a play based upon the events of Salem, Massachusetts in 1692. The story is about a religiously motivated town. The story is about a group of girls’ who are led by Abigail, who blamed witchcraft for their troubles. Being a strict Christian society the people of Salem believed in the girl’s stories. In conclusion this led into 20 people being falsely accused, and hung. The girl’s stories were easy to believe because of many reasons. Salem town was filled in a Puritanism belief. Everything they did was for God; they were doing God’s work. With this they believed that the bible was the ultimate answer to any question. When something went wrong they would automatically look into the bible and the teachings of God and anything it said they would abbey to it. John Proctor is accused of being a witch when he forgets his 10 commandments. He forgets to mention about not committing adultery. Proctor replies to this by saying, â€Å"I think it may be a small fault†, with Hale replying, â€Å"Theology, sir, is a fortress; no crack in a fortress may be accounted small†. Because they lived in a society that was strict and suspicious about everything because they were paranoid with fear. Hale suggests that because has forgot to mention adultery that Proctor doesn’t see it as a problem and will commit adultery. The people of Salem would swiftly blame the devil as when something bad or evil would happen. Towards the beginning of Act One we see this when Betty falls sick and Mrs Putnam says, â€Å"I’d not call it sick; the Devil’s touch is heavier than sick†, this shows us what a strongly religious society Salem was at this time. This makes the ... ...he liked her power. She likes to be in control. The society has a strong pride. With the people of Salem not confessing to the witchcraft. Because they didn’t admit they assumed that they did do the witchcraft, so the girl’s stories were easy to believe even more so. In conclusion the girl’s stories were easy to be believed because the society of Salem was an extremely religious. They were paranoid with fear, which made them venerable to small things: causing superstition. Another reason why the girl’s stories were easy to believe was because people wanted to believe them so they could end old grudges and claim land. People were scared to question the Bible because they would be accused of doing the Devil’s work and then hung. The Religious views about Christianity were taken too literally and as a punishment over 20 people were hung because of it.

Thursday, October 24, 2019

Effective Parenting Styles

Effective Parenting Styles COM/150 Abstract The passion of people’s reactions to questioning parenting styles are just below the nukes of religion and politics in explosive potential. Here we discuss what the basic styles are and what styles most parents tend to fall. We will look at constructive and deconstructive parenting styles as well as see which option tends to be the best. Where do you fall? Is that style the best your family or are you still seeking guidance? Effective Parenting StylesAlthough parenting is a never-ending debate, many parenting styles have been studied to find what elements are constructive and which are destructive. There are roughly four major parenting styles identified when researching effective parenting. Each parenting style can differ and change as children grow older, or change based on each individual child. These groups defined below have a major emotional impact and development impact on a child. Permissive Parenting Permissive parenting can come off to be more of a friend rather than a parent; these parents don’t often discipline their children.Parents who choose to parent their children this way rarely have control over their children and may be lacking self-discipline themselves. Although these parents are still very loving and nurturing to their children, this parenting style may be a bit too laid back to raise an obedient child with self-discipline. Authoritarian Parenting In the authoritarian style of parenting, the parents set strict rules for children to follow and set high demands that these rules are to be obeyed or they be punished end of story.The most common aspect of this authoritarian style of parenting, is the parent neglects to give the child reasoning to the rules they have set, â€Å"Because I’m the father that’s why† is the perfect example of this. Parents in this style don’t feel they need to have to explain reasoning to their children and often come across as an aggressor. Communication between parent and child is non-existent. Authoritative Parenting This parenting style has much in common with the authoritarian style of parenting. The authoritative style parenting is a bit more self-ruled and flexible for each disciplinary incident.The authoritative style has the same set rules and standards as authoritarian, but parents in this style are more expectable to reason with these children and dig deeper into the issue at hand and discuss a resolution then jump straight to discipline. This style does discipline and sticks to the rules, but has more of an emotional and nurturing way of dealing with the issue. Uninvolved Parenting Uninvolved parenting style is just that. Parents of these children have no receptiveness or awareness to their children’s behavior.These parents are disconnected from their children on most emotional levels and just fill the basic living demands of food, water, shelter, etc. There is low to none communication, di scipline, or nurturing between parent and child. In some extreme cases, parents don’t even meet the child’s basic living demands. When it comes to parenting styles we find two major deconstructive styles out of the four listed above, uninvolved parenting and permissive parenting. Children raised with the permissive styles generally experience more problems with school, authority, and are found to have self-esteem issues.This child hasn’t had much authority from parents so they feel that they shouldn’t have to take any from anybody else including the law. This can majorly effect education if the child has no consequence for not finishing homework or sees no reason education and guidance are important to learn. The results of the uninvolved parenting style can lead to children being less competent in adult life, un-successful, have problems dealing with self-control, and also are found to have major self-esteem concerns.Children raised in these environments have little to no control over emotions and actions since proper guidance was never shown to them. These children learn and grow from what they know and seek acceptance from outside sources. Too often enough these children fall into gangs and drugs to seek this acceptance from these groups. Many of these children drop out of school at an early age and suffer from poor reading and writing skills. After reviewing the parenting style definitions above, the most logical and constructive parenting style seems to be the authoritative parent.Numerous studies have been taken on these four parenting styles and have concluded â€Å"Authoritive parenting styles tend to result in children who are happy, capable and successful† (Maccoby, 1992. These studies also show that the Authoritarian parenting styles â€Å"generally lead to children who are obedient and proficient, but they rank lower in happiness, social competence and self-esteem. † (Cherry,  n. d). Giving your children the extra attention and guidance while setting reasonable boundaries seems to be the best fit for parenting. Every parenting style varies.You may have a father who is authoritive, the mother is more permissive; the key to successful parenting is communication and balance as a family. Communicate with your children about why they did what they did. Guide them and show them how it can be done better the next time around, and most of all make sure to make to show your child love and acceptance. Punishment needs to happen like committed as consistency is also very important, but following through with rules and the punishment allows your child to grow and learn from the experience, and to avoid doing them again.Conclusion All children need a good parent with an effective parenting style. Who the child grows up to be is a direct look at who the parent is. References Maccoby, E. E. (1992). The role of parents in the socialization of children: An historical overview. Developmental Psycholo gy, 28, 1006-1017. Cherry, K. (n. d). About. com – Education- Psychology. Retrieved from http://psychology. about. com/od/developmentalpsychology/a/parenting-style. htm

Tuesday, October 22, 2019

Ophelia is very happy Essay

The Nunnery scene in the Gibson version occurs in a large open hallway or court, Claudius and Polonius observe from a balcony above, giving a slight suspenseful atmosphere with the thoughts of the crowd wondering if Hamlet will discover them or whether he knows they are there already. Ophelia is stood clutching some belongings and she tries to be very kind and considerate to Hamlet, and Hamlet seems to be acting strange towards her, but not nasty or violent at this stage, just a little preoccupied with his emotions and trying to demonstrate his antic disposition. Hamlet begins to speak with Ophelia quite strangely, with a very jumpy attitude, grabbing her and then pushing her away. Ophelia has obvious love for Hamlet yet she fears him because of his apparent madness. Hamlet sees the shadows of Claudius and Polonius, and suddenly has a more serious, less playful tone with her. He asks where her father is, and she replies with a lie, telling him he is at home. This is an obvious turning point for Hamlet as he suddenly becomes quite enraged, and is quite aggressive with Ophelia, pushing her and shouting loudly, as he makes his exit with an insult, declaring â€Å"I say, we will have no more marriages. Those that are married already, all but one, shall live; the rest shall keep as they are. † To me this scene is very successful in conveying all four of the characters thoughts, emotions and feelings for each other. Hamlet is busy plotting and scheming in his mind, yet becomes emotionally wounded by the fact Ophelia lies to him and betrays him to his enemy. Ophelia is torn between her father and her love for Hamlet, and when he tries to show his antic disposition to her, with the tense atmosphere increasing it becomes very apparent that she is doubting whether he loves her at all anymore. Claudius and Polonius both show slight emotion on their faces, seeming surprised at some of Hamlets strange and slightly insane reactions to Ophelia. In the Brannagh version, the scene takes place directly after the soliloquy as Shakespeare intended, and there are very high emotions between the two who obviously love each other strongly, with much hugging and kissing to start with. Also the atmosphere from the soliloquy scene is still in the air. Ophelia is very happy, and Claudius and Polonius observe from behind a mirror, quite inanimately. There is an obvious turn in Hamlets behaviour when she offers him the gifts back. He slaps them to the floor and begins to shout at her, then quite violently grabs her and drags her over to the mirrors in the hall where he one by one starts opening them looking for a spy, ranting and raving in quite an insane manner. He gets to the mirror where Claudius and Polonius are sat and presses Ophelia against it, and the audience are left unaware as to if Hamlet is aware of their presence or simply a suspicion or is completely oblivious, either way the mirror plays a role in this, Hamlet pressing her against it shows he is trying to make her look at herself and at her life, as he has been doing. He finishes his rant, then proceeds through the mirror to an empty room as Claudius and Polonius have already fled. This scene also has a lot of tension, with quick flying emotions and sudden changes of attitude toward one another. It is successful at showing Hamlets antic disposition to the audience, and makes Claudius and Polonius aware of his state. Also, it is apparent that Ophelia begins to doubt whether Hamlet really loves her or not, and allows the audience to really feel the raw emotions felt by each of the characters. In the Hawke version the scene takes place in Hamlets apartment, where Ophelia sits at a table with some gifts. They talk quite unemotionally in a laid back manner, Hamlet offers her a beer e. t. c. They begin to talk and they get quite emotional, or lustful, and begin kissing and groping in a sexual manner, and Hamlet opens her top and finds a wire which Ophelia seemed to have forgotten about in the heat and passion of the moment. Hamlet is angered and begins to shout, Ophelia is evidently distressed, Hamlet is quite aware that Claudius and Polonius are listening and shouts down the microphone, making it apparent to the audience that Hamlet feels distraught and betrayed. With his anger there is an obvious disappointment in his feelings as he believes that Ophelia loves him but she lied to him which saddens him greatly. The decision to play out this scene in a modern apartment is an innovative idea, and will appeal to a modern audience, but like the other scene it lacks the atmosphere, it leaves out a lot of the raw, heartfelt emotions which are conveyed much better by traditional settings and acting. Also, this version seems to focus on Hamlets depression, rather than on his humanity and contemplative states of mind, which again will relate to a modern audience more, but lacks a lot of his true character. Overall I think the three approaches were very well thought out and planned, and the use of language, settings and re-arranging the scenes worked well in all three versions, but overall I am more of a fan of the Zefferelli version, perhaps due to Gibson’s excellent portrayal of Hamlet as an unstable man with too much to deal with, but I felt he could get the emotional value the audience needs to really feel Hamlets character. Brannagh’s version also was very successful at conveying the emotional state of hamlet, but somewhat lacked the antic disposition part, which helps make Hamlet. The Hawke version was also very successful, but I feel it was trying to please the modern day audience rather than produce a really good Hamlet play, focusing on a depressing point, lacking the insane, raw emotional value the other versions succeeded in conveying.