The Definition of a Ultra Low Emissions Vehicle (ULEV)

The Definition of a Ultra Low Emissions Vehicle (ULEV) ULEV is an abbreviation for Ultra Low Emission Vehicle. ULEVs discharge emanations that are 50 percent cleaner than the present normal years models. ULEVs take the LEV, Low Emission Vehicle, standard above and beyond yet dont yet fit the bill for Super-Ultra Low Emissions Vehicle (SULEV) status. Albeit effectively an idea in vehicle producers wheelhouse, the ascent in prominence of ULEV vehicles came after a decision by the California courts in 2004 that every single new vehicle sold in the state must have in any event a LEV rating. Comparative measures passed by the United States Environmental Protection Agency (EPA) on vehicle outflows guidelines have likewise offered ascend to the ubiquity of eco-accommodating vehicles.â Sources of Low Emissions Because of the EPAs 1990 revisions to the Clean Air Act of 1970, light-obligation vehicle producing started to experience a staged usage of cleaner emanations guidelines. Ordinarily confining the yield of an excessive amount of carbon monoxide, non-methane natural gasses, oxides of nitrogen, formaldehyde, and particulate issue, these guidelines tried to scale down the carbon impression of the vehicle business in the United States. The eliminates of this arrangement moved Tier 1 characterizations from 1994 through 1999 with Tier 2 executed from 2004 to 2009.â As a major aspect of Californias 2004 low-discharges vehicle activity, which gave a lot stricter guidelines to qualifying as a low-emanation vehicle, the levels were additionally stalled into six sub-arrangements: Transitional Low-Emissions Vehicles (TLEV), LEV, ULEV, SULEV, Partial-Zero Emissions Vehicle (PZEV) and Zero Emissions Vehicle (ZEV). In 2009, President Barack Obama reported another activity to additionally diminish discharges yields for American auto customers. This included extending the arrangements definitions just as normalizing Californias 2004 bill as a governmentally ordered program, expecting makers to deliver a net emanations yield of their vehicles (which means the joined normal of every vehicle discharges rating) that equaledâ more than 35.5 miles per gallon. Normal Examples The quantity of ULEVs out and about has exponentially expanded yearly since 1994, however it wasnt until the 2010s that the market for LEVs truly took off. In any case, many years of experience have shown vehicle makers a certain something: eco sells. To an ever increasing extent, organizations are hurrying to meet prerequisites for their vehicles to qualify as LEVs. Instances of these Ultra-Low Emissions Vehicles have started springing up increasingly more every now and again beginning with 2007s Honda Odyssey minivan, the 2007 Chevrolet Malibu Maxx and the 2007 Hyundai Accent. Costs are normally midrange for these mid-extend low-emanations cars, urging more shoppers to be eco-cognizant with their driving habits.â Luckily, the appearance of such mileage estimating devices as the moment efficiency displayâ also encourages battle fuel burn through by making drivers aware of the ongoing miles per gallon fuel utilization their vehicle requires to work given the drivers treatment of the vehicle. Most vehicles created in the United States currently qualify in any event as LEVs, with outflows no matter how you look at it presently down to short of what one percent of discharges permitted in the U.S. in the 1960s.â Before long, ideally, we will move further away from gas dependent vehicles and rather change to electric or hydro-fueled motors.

To love and to be loved

To love and to be loved Once upon a time .A very poor man lived with his wife. One day, his wife, who had very long hair asked him to buy her a comb for her hair to grow well and to be well-groomed.The man felt very sorry and said no. He explained that he did not even have enough money to fix the strap of his watch he had just broken. She did not insist on her request.The man went to work and passed by a watch shop, sold his damaged watch at a low price and went to buy a comb for his wife.He came home in the evening with the comb in his hand ready to give to his wife.He was surprised when he saw his wife with a very short hair cut. She had sold her hair and was holding a new watch band.Tears flowed simultaneously from their eyes, not for the futility of their actions, but for the reciprocity of their love.Moral of the story: To love is nothing, to be loved is something but to love and to be loved by the one you love, that is everything.Author Unknown Story submitted by Tina

Analysis Of Shakespeare s Sonnet, Let Me Not And The...

Comparisons of Shakespeare s sonnet â€Å"Let Me Not in to the Marriage of True Minds† and Sherran s composition â€Å"Thinking Out Loud† In the poem â€Å"Let Me Not in to the Marriage of True Minds† also known as â€Å"Sonnet 116† Shakespeare uses the theme that love endures; to articulate that in spite of obstacles, true love never expires. First, he defines love as having a decree. For example, over time circumstances and a person can change, but Shakespeare declares that love can not be influenced. After explaining the regulations of love Shakespeare defines love as having no boundaries. For instance, throughout the sonnet he clearly indicates that love cannot move, be measured or die. Much like Shakespeare, Ed Sheeran wrote the song â€Å"Thinking Out Loud† with a similar theme of love s endurance; although, Sheeran marvels over love and how age will affect the circumstances of a persons true feelings. For example, Sherran writes about how age, memory, and looks default over time, and contemplates if he and his lover will still feel the same way about each other after time alters their mind s and bodies. Using the endurance of love as a theme to teach that love is eternal, Shakespeare uses metaphors and personification; however, Sheeran questions love s lasting effects by using personification and hyperbole. Shakespeare uses his theme to inform people of everlasting love with his use of metaphors and personification. For example, in lines 5-7 he states, â€Å"O, no it is an ever fixed mark,

America s National Government And Fundamental Laws Essay

On September 17, 1787, our founding fathers decided to sign their name to a document that would forever be the foundation of a nation unlike any other. A document that would â€Å"establish America s national government and fundamental laws, and guarantee certain basic rights for its citizens†¦[as well as] a plan for a stronger federal government with three branches–executive, legislative and judicial–along with a system of checks and balances to ensure no single branch would have too much power† (History Staff). In order for this government to be established, political parties were founded to help represent the ideals and differing views of all of the citizens. Throughout America’s history, the Democratic and Republican parties have grown to become the two major parties in American government. These parties are important to the electoral system as each party represents the â€Å"embodiment of shared principles, goals, and policy positions among a certain subset of citizens† (Gripp). With the election coming up on November 8th, 2016, the Democratic party has chosen Hillary Clinton as their candidate while the Republican party has selected Donald Trump to represent their views. These two candidates differ greatly on global trends issues such as globalization, immigration, and the influence of Islam and terrorism on the United States. One of the top three most discussed topics in this election is globalization. Globalization is the â€Å"means that prices for commodities tend toShow MoreRelatedProtecting Fundamental Rights Of Citizens888 Words   |  4 PagesProtecting Fundamental Rights of Citizens â€Å"A civil right is an enforceable right or privilege, which if interfered with by another gives rise to an action for injury† (â€Å"Civil Rights†). In his article â€Å"To Begin the Nation Anew: Congress, Citizenship, and Civil Rights after the Civil War,† Robert J. Kaczorowski discusses the relationship between civil rights and the constitution laws of the 1860s. The federal government creating amendments and laws â€Å"that conferred on all Americans the preciousRead MoreShould Citizens Of The United States All Have The Same Rights?911 Words   |  4 Pagesexercising what are everyday rights at home. Americans who have paid hard earned money to enjoy the very freedoms being threatened have the most to loose. Let’s look into the laws regulating concealed carry in America today and their constitutionality. The second amendment has been a point of contention for years in America. It has been subject to much scrutiny and interpretation. Cases during the 1800s saw the Supreme Court rule that the Second Amendment does not affect individual states regulatingRead MoreThe Birth Of America Is Well, The Biggest And Greatest1228 Words   |  5 PagesThe birth of America is well, the biggest and greatest thing to ever happen to us. 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(The Constitution) We theRead MoreThe Progressive Era Of The Revolutionary Era1723 Words   |  7 Pagessome terrible problems and they wanted to work together to change the U.S government. Therefore, address the prob lems that had come about from the Industrial Revolution. The progressive era was all about making advances in a better society, the feature of democracy during the progressive movement a lot of these progressive at local state levels started to focus on cleaning up the government, they believed that too many governments elected officials did the bidding of corporations rather than serve theRead MoreNational Security Vs. Digital Privacy1735 Words   |  7 Pagesterrorism rates in America, the optimal solution thus far is enhancing security throughout the nation. By doing so, policies, procedures, and protocols would be amended for the sole purpose of protecting the country. 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Chemistry Titration Lab Free Essays

Table 1: Data Collection Table – Contains all of the primary data directly obtained from the lab. Indicator | Initial volume of NaOH in burette (ml)  ±0. 05| Final Volume of NaOH in burette (ml)  ±0. We will write a custom essay sample on Chemistry Titration Lab or any similar topic only for you Order Now 05| Final – initial Burette Reading (Volume of NaOH used) (ml)  ±0. 1| Qualitative Observations | Phenolphthalein | 0. 00 | 0. 90| 0. 9| At first when the base was being dropped into the vinegar there wasn’t a color change, however when the solutions came close to full titration, the solution would turn pink and once mixed would turn clear again| | 0. 90| 2. 30| 1. 4| | | 2. 30| 3. 20| 0. 9| | | 3. 20| 4. 0| 0. 9| | Bromothymol Blue | 8. 00| 9. 50| 1. 5| Solution turned from yellow to light green | | 9. 50| 11. 10| 1. 6| Solution turned from a bright yellow to bright blue rather than a light green indicating over-titration had occurred| | 11. 10| 12. 90| 1. 8| | | 12. 90| 14. 40| 1. 5| | | 14. 40| 15. 90| 1. 5| | Methyl Orange | 15. 90| 16. 90| 1. 0| Reaction occurred quick, over-titration occurred and solution turned from red to orange | | 16. 90| 17. 20| 0. 3| | | 17. 20| 17. 40| 0. 2| | | 17. 40| 17. 60| 0. 2| | | 17. 60| 17. 80| 0. 2| | Methyl Red | 0. 00| 5. 00| 5. 0| | | 5. 00| 7. 80| 2. | Solution turned from red to a light orange/yellow color| | 7. 80| 10. 70| 2. 9| | | 10. 70| 13. 60| 2. 9| | | 13. 60| 16. 50| 2. 9| | Bromocresol Green| 20. 80| 21. 20| 0. 4| Solution turned from yellow to light green | | 21. 20| 21. 60| 0. 4| | | 21. 60| 22. 00| 0. 4| | Table 2: Data Processing Table displaying the volume of NaOH required to titrate 10ml of vinegar and their corresponding concentration of acetic acid Indicator | Volume of NaOH required to titrate 10mL of Vinegar (ml) ( ±0. 1)| Concentration of Acetic Acid  ±0. 5 (mol/l) | Percent Uncertainty (%)| Percent Error (%) | Phenolphthalein| 0. | 0. 9mol/dm3| 11. 1| 3. 4| Bromothymol Blue | 1. 5 | 1. 5mol/dm3| 6. 7| 72. 0| Methyl Orange| 0. 2| 0. 2mol/dm3| 50. 0| -77. 0| Methyl Red | 2. 9| 2. 9mol/dm3| 3. 5| 233. 0| Bromocresol Green| 0. 4| 0. 4mol/dm3| 25. 0| -54. 0| Sample Calculations: Ex. The calculation of the concentration of acetic acid for phenolphthalein NaOH Volume: 0. 9ml NaOH Co ncentration: 1. 00mol/dm3 1. Convert Volume to Litres 0. 9 = 0. 0009L 1000 1. Calculate the moles of NaOH (n=CV) n= (1. 00mol/dm3) (0. 0009L) = 0. 0009mol 2. Calculate the concentration of the diluted acetic acid. Because acetic acid and sodium hydroxide have a 1:1 ratio, they have the same number of moles. C = 0. 0009mol = 0. 09 0. 01L 3. Calculate the initial concentration of acetic acid pre-dilution C1V1 = C2V2 C1(0. 01L) = (0. 09mol/L)(0. 1) Concentration of Acetic Acid = 0. 9mol/L Sample Calculations Continued 4. Calculating percent uncertainty = absolute uncertainty x 100 Measurement 1 Example: Calculating the percent uncertainty for the volume of NaOH required when methyl red is used = 0. 1 x 100 2. 9 1 = 3. 5% Therefore, the volume of NaOH required when methyl red is used as the indicator is 2. 9ml  ± 3. % 5. Uncertainty propagation for the volume of NaOH required for each indicator (0. 9  ± 0. 1) + (1. 5  ± 0. 1) + (0. 2  ± 0. 1) + (2. 9  ± 0. 1) + (0. 4  ± 0. 1) = 5. 9ml  ± 0. 5 6. Calculating percent error Percent error = Actual – accepted x 100 accepted Example: Calculating percent error for phenolphthalein Percent error = 0. 9 – 0. 87 x 100 0. 87 = 3. 4 % Methyl Red Methyl Red Bromothymol Blue Bromothymol Blue Bromocresol Green Bromocresol Green Methyl Orange Methyl Orange Phenolphthalein Phenolphthalein Graph 1: Titration curve representing the effect of the volume of NaOH on the pH of the titration solution at end point Conclusion This lab tested the effect of the use of different indicators on the volume of NaOH required to reach the end point of the titration with acetic acid in vinegar. The equation for this reaction is: CH3COOH(aq) + NaOH(aq) NaCH3COO(aq) + H2O(l) The As one can see from graph 1 the results of this lab demonstrated that the indicators that required different volumes of sodium hydroxide to reach end point from least amount of volume required to most was with the use of; methyl orange, bromocresol green, phenolphthalein, bromothymol blue and lastly methyl red. Therefore, the highest volume of NaOH that was required to change the color of the vinegar occurred when using methyl red, and the smallest volume of NaOH that was required to change the color of the vinegar occurred when using methyl orange. Different indicators were tested as if the indicator is chosen well, then the endpoint will represent the equivalence point of the titration reaction; the point when the volume of titrant is equal to the amount of analyte (the acetic acid in the vinegar). An important factor to consider is hat indicators don’t change color at a specific pH. However, they do change color over a narrow range of pH values. Because vinegar has a pH of around 2. 4 the equilibrium was firmly to the left before the sodium hydroxide was added. Adding the sodium hydroxide will begin to shift the equilibrium to the right. As more and more base was added, for example with phenolphthalein, the pink eventually became so dominant that it could no longer be turned clear by swirling the beaker. If the light pink was achieved, then end point was perfectly reached and if the solution became bright pink then over-titration occurred. Although the majority of this lab occurred according to plan, there were a few minor anomalous results that occurred. For instance, the amount of NaOH used in the titration when the methyl red indicator was used was 2. 9ml. However, for one of these tests when using methyl red, the volume of NaOH required to reach the end point of the reaction was 5. 0ml. This was a clear anomalous result as it was very different from the consistent 2. 9ml of NaOH from the other trials. This anomalous result can be explained due to several systematic and/or random that will be discussed further on with their potential improvements. There were no error bars included in this lab. This is due to the fact that they would be non-existent as each titration was repeated until the exact same volume of NaOH was required to reach the end point for each different indicator at least 3 times. Figure 1: Representation of the various indicators used throughout the conduction of this lab and their pH levels. It also demonstrates their colors in acids and colors in bases as well as the color when end point is reached. This lab evidently demonstrated that phenolphthalein would be the best indicator to use. The justification for this is that every indicator has their own individual range of pH for the end points. When the end point occurs, it means there is slightly excess base. For phenolphthalein, the end point would be when the color of the solution changed into a very light pink color. As one can see from figure 2 the indicator phenolphthalein only changes color in basic solutions. This is a reason why it would be considered the best indicator for this experiment. This is because the end point for this experiment ranges in between a pH of 8. 2 and 10. , which as one can see is very similar to the pH ranges of phenolphthalein. This would cause the phenolphthalein to give the most accurate reading of the volume of NaOH required to reach the end point of its reaction with acetic acid. The reason the other indicators may not give the most accurate readings can be seen from the diagram below: Graph 2: This graph represents a simple visual of the effect of different indicators on the volu me of base required to reach end point with an acid. The green block above represents the phenolphthalein in this lab as it has its pH ranges on the break of the curve. This means that the color change will be accurate in terms of changing color at the break point of the reaction Evaluation There are a variety of ways this lab could be furthered. This lab was done using a strong base (NaOH) and a weak acid (acetic acid). A way that this lab could be furthered would be to do the exact same lab using a weak base and a strong acid such as NH4OH (ammonium hydroxide which is a weak base) the same weak acid (acetic acid). This would skew the results in that a much higher volume of base would be required to reach end point with the acid. This is because it would be much more difficult to shift equilibrium o the right. For example, the phenolphthalein indicator only turns the solution pink in basic solutions. Because a weak base is what will be used, it would take much more base in order to reach end point of the reaction. There were a few errors that could have been improved throughout the conduction of this lab. One of the major errors occurred prior to t he actual titration itself. This error occurred when the sodium hydroxide solution was being created. When the sodium hydroxide was being created, 1g of solid sodium hydroxide pellets had to be weighed using an electronic balance and then put in a volumetric flask. After this water was added to the sodium hydroxide pellets and diluted to the 150ml mark. The pellets were left in a dish in the open while we were getting other materials set up. This was definitely an error as the sodium hydroxide pellets absorb moisture from the air. This means that the sodium hydroxide was actually becoming heavier than 1g as it began absorbing his moisture. This affected results as there was a higher concentration of sodium hydroxide in the water than recorded. This could have affected the results in that less sodium hydroxide would have been required to reach the end point of the reaction. This would be considered a systematic error as the slightly increased mass of the NaOH would have been used for every trial as the same source of NaOH was used throughout. An improvement to this error would be to not put the sodium hydroxide pellets into the volumetric flask until the very last second. Also, the sodium hydroxide was put into the volumetric flask and then the water was added, however adding the water first could minimize the time that the solid sodium hydroxide is left in the air. This step in the procedure could also be improved if it were possible to purchase this solid sodium hydroxide already measured out in grams so that they would only be in the open for a matter of seconds as they were being transferred into the volumetric flask. A systematic error that occurred throughout the process of this lab was over-titration. Over titration is when too much of the base is added to the solution and the reaction passes end point. For example, the color that one would attempt to achieve when perfectly titrating using phenolphthalein is a light pink color. However, for all of our trials the solution turned a bright fuchsia color when using phenolphthalein implying it had over-titrated. This error could definitely have been improved. The improvement for this error would be to use a burette with a smaller opening. This would allow decreased room for the error of over-titration. This is because one would have more control over the volume of base released by the burette allowing for more control. Another systematic error that occurred repeatedly throughout the conduction of this lab was that the temperature of the room did not stay constant. Therefore, the temperature of the solutions including the indicators was not constant. Temperature changes could have occurred in the lab without being noted. This is a problem as it slightly changes the color change pH range of indicators. As one can see below, these are the effects on various common indicators’ color change ranges with an increase in temperature: Table 3: Table representing common indicators and the effect of changing temperature drastically on the color change range. Although the temperature would not have fluctuated drastically in the classroom there were still potential fluctuations that were not accounted for. This would have caused the end point to appear to be occurring at different times than expected for that indicator. The way this error could be improved would be to conduct the lab in an area where the temperature is closely and easily monitored. Conducting this lab in a classroom with the door frequently opening and shutting let in a draft therefore this lab should be conducted in an area with no interruptions that may effect temperature. Also, temperature can be monitored so that it can be at least accounted for in one’s results and the changes in temperature can be used as an explanation for the behaviour of the indicators in each test. Another section of the procedure of this lab that requires improvement relates to the indicators used. The indicators used throughout the process of this lab had pH ranges of around 2-3 increments. For example, phenolphthalein changes color over a pH range of around 8-10. This means that one would not be able to tell exactly what pH the final solution was when it reached end point from the indicator. This could be improved if indicators were produced that did not have a range of pH values in which they change color but one specific pH range where it changes the color of the solution. This would improve the lab as it would allow scientists to know exactly at which pH the end point of the reaction was reached exactly when it happens. For example, this specific experiment is supposed to reach end point between pH values 8-10, however having an indicator that changes color at pH 8, one that changes color at pH 9 and one at 10 would allow for a more accurate result. An additional random error that occurred throughout the process of this lab was that rarely a drop of NaOH wouldn’t come out of the burette completely straight and would end up getting stuck to the side of the beaker. This would have caused the volume of NaOH required to reach end point of the reaction to appear greater than it actually was. This is because NaOH was leaving the burette but not going into the beaker containing the vinegar and indicator. Although one cannot control the behaviour of the burette with the NaOH other than potentially using a burette with a thinner opening allowing for less room for the NaOH to fall from obscure angles, one can control beaker size. By increasing the size of the beaker containing the vinegar and the indicator, one is able to reduce the likelihood of the NaOH not going directly into that beaker. This would mean that there wouldn’t be as much NaOH lost from the burette that isn’t accounted for. Often in the real world, titration experiments are performed regularly. This is because titration is a process of determining the concentration of a substance in an unknown solution, in which a known reagent is added to that unknown solution in order to produce a known reaction such as a color change. A real world example of this is biodiesel production. Acid-base titrations are used in the production of biodiesel in order to determine the acidity of waste vegetable oil (one of the main ingredients in biodiesel production). pH paper is used to test a small sample in order to represent the pH of the entire batch. This allows one to determine how much base is required to achieve the desired pH. Bibliography Websites: â€Å"Chemical Analysis by Acid-Base Titration. †Ã‚  AcidBaseTitration. N. p. , n. d. Web. 12 Nov. 2012. http://chem. lapeer. org/Chem2Docs/AcidBaseTitration. html. â€Å"ChemTeacher.   ChemTeacher. N. p. , n. d. Web. 12 Nov. 2012. http://chemteacher. chemeddl. org/services/chemteacher/index. php? option =com_content. â€Å"Sample Lab Report. †Ã‚  Sample Lab Report. N. p. , n. d. Web. 12 Nov. 2012. http://www. chem. purdue. edu/courses/chm115/Laboratory/Records___Reports/Sample_Lab_Report/sample_lab_report. html. â€Å"Titration Lab Report. †Ã‚   Titration Lab Report. N. p. , n. d. Web. 12 Nov. 2012. http://www. slideshare. net/AuburnFeather/cfakepathtitration-of-7. Books: Textbook: Talbot, Chris. Chemistry for the IB Diploma. London: Hodder Murray, 2009. Print. How to cite Chemistry Titration Lab, Essay examples

Goals of Higher Education free essay sample

Living in the modern world, one cannot but face with a neÃ' essity of getting higher education. Thus, if you want to be a respected part of society, you are to have a degree. However there are a lot of people who tend to think that this kind of studies is not for them as school education is quite enough. Well, what are the goals of higher education? And do people really need it? To give some facts I’d like to mention that due to the statistics, our country stands at the first place in the world in the number of people who have higher education with 54 % people graduated from the university. It’s very impressive though. So, what were the aims of all these people? Definitely, everybody is looking for the advantages one can take of it. And frankly speaking there are plenty of them. In my opinion, one of the most important goals of higher education is providing society with highly qualified manpower in order to strengthen particular sector of domestic and world economy as well as other spheres of social life. We will write a custom essay sample on Goals of Higher Education or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Hence graduates have more chances to get a well-paid job and higher position in the field he or she interested in. Secondly, being educated in a certain realm gives you an opportunity to become an expert in a wide range of problems. Consequently, another goal of higher education is cultural enlightment. What is more, university or college really matters when we are talking about self-determination. Thus, it helps one to gain independence by realizing what he or she is good at. Sometimes school leavers enter higher education institution without knowing whether they really want to study this or that. However, with every passing year there, their desires become specified and they discover more and more opportunities to become useful for their local as well as world communities. Once I realized that higher education is vital for me, there was a problem what university to enter. However the number of universities offering studies in the field of international affairs in our country is quite limited and I had to choose between two cities, Volgograd where I was born and Samara that was quite near to my place. Finally, I made up my mind to study in Samara State University and I’ve never regretted it yet. It is a classical multi-faculty university and a leading educational institution of higher education in the region. What is more important for me, it offers a great platform for students who are interested in carrying an individual research. Highly qualified scientific advisors are ready to help us and provide with essential literature whenever we need it. Moreover the conferences held in our university give the youth opportunity to be heard and noticed as a lot of experts visit them. All things considered, we can notice that all the goals of higher education are to improve the quality of life in this or that way. Although, a lot of people are aware of all these advantages they prefer to limit themselves with school education. The point is that we shouldn’t forget that improvement of the quality of our life is about everybody. Therefore, it’s obvious that the more people have higher education, the better life we have. And the only choice you should make is what university to enter but in no case to keep studying after school or not. That’s out of question.

Molecular stability (rheology) of a plastic carrier bag through stress strain tests Essay Example

Molecular stability (rheology) of a plastic carrier bag through stress strain tests Essay I am going to study the molecular stability (rheology) of a plastic carrier bag through stress strain tests. I will do this through a simple viscoelastic experiment of where I will be able to calculate the Young Modulus and assess Hookes Law. Plastic carrier bags are made from polyethylene or polyethene, which is a homopolymer. Polyethylene comes from ethylene. Ethylene is an alkane made up of a series of saturated hydrocarbons. The alkane series are known as homologous series as they share the properties and general formula: (CnH2n+2) 1.1 Origin of plastic Essentially plastics are materials that can be heated and moulded and maintains this moulded shape once it cools. We will write a custom essay sample on Molecular stability (rheology) of a plastic carrier bag through stress strain tests specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Molecular stability (rheology) of a plastic carrier bag through stress strain tests specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Molecular stability (rheology) of a plastic carrier bag through stress strain tests specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Plastics have existed since the beginning of time. Plastic contains natural elements such as carbon(C), hydrogen (H), nitrogen (N), chlorine (Cl) and sulphur (S). These elements can be originated from naturally grown organic materials such as wood, horn and rosin. Animal horn and amber are examples of natural plastics. Already renown for his work in the rubber industry, Alexander Parkes invented a material that was based on cellulose nitrate at the Great Exposition of 1862 in London. He called this material Parkesine, which was the first synthetic polymer. His invention was due to a new scientific movement to utilise by-products of natural gas production. We are now in the Age of plastics where plastic dominates our industrial world. Plastic is a force that will shape the twenty-first century, bringing to fruition new wonders in tomorrows world. Carin Glaser 1.2 Polymer Polymer comes from the Greek word, poly meaning many and mer meaning part. Polymerisation is the chemical process of forming polymers from their components of monomers. Polymerisation is often an intricate process that may be initiated or sustained by pressure, heat or with catalysts. Monomers generally contain carbon and hydrogen including, sometimes, chlorine, nitrogen, oxygen or fluorine. A polymer is a chemical compound with a high molecular mass constructed of chains of monomers linked together through bonds. Polymers can be categorised into two forms of polymers, addition polymers and condensation polymers. Condensation polymers consist of repeats of units that are bonded, which contain fewer atoms than the original monomer/s because of the loss of substances such as water. Addition polymers consist of the same monomer units that attach one at a time i.e. they have the same structural unit. A resultant of additional polymerisation, of monomer to polymer, with polyethylene is shown below. Ethylene; Polyethylene; 1.3 Cracking in the plastics industry Cracking is a process in industry where large chains of aliphatic hydrocarbons that make up crude oil/petrochemicals are broken down into smaller, more useful fractions. Factors such as high temperature, high pressure and catalysts are needed to break these long chains into shorter chains. Petrochemical such as oil or natural gas contain hydrocarbons. These hydrocarbons are processed through a reactor into a procedure known as cracking. In the plastic industry a natural gas derivative known as resin is produced. Resin pellets are then moulded or formed to produce several different kinds of plastic products with application in many major markets. The fickleness of the resin pellets proves a complex resin to be specifically designed for the consumers requirements. The different resins produced in the industry is the reason why certain plastics are better for different applications while others are best suited for entirely different applications. The production of a plastic bag is done through a process known as blown film extrusion. This process involves the resin being blown up and extruded to produce tubes of film. 1.4 Polymerisation of ethylene Branched polyethylene is produced through a free radical addition reaction. As shown above polyethylene are ethylene molecules bonded together. There are three stages to this process, these are: 1.4.1 Initiation Oxygen is the initiator of this process. The oxygen reacts with the ethylene to produce organic peroxide. Oxygen peroxide consists of double oxygen single bonds that are extremely reactive and break easily to give free radicals. This process can be avoided by adding other organic peroxides directly to the ethylene. The free radicals vary depending on the source, the basic formula for these free radicals is Ra*. These free radicals then react with the monomer to find its pair. This then pushes the monomers molecule leading the reaction back to the free radical stage. 1.4.2 Propagation The adding of more and more monomers to the growing chains is called propagation. The conductor of the experiment can add extra ethylene molecules to construct a long chain of them. Self-perpetuating reactions like this one are called chain reactions. The ethylene molecule consists of a double bond. One pair is held loosely on an orbital, this is known as a pi bond. The other pair is called a sigma bond and is held sturdily onto the nuclei. The free radical breaks the pi bond to form with another monomer. This is efficient because the previously weak pi bond is broken and the new carbon bond is stronger. This concluding that the more energy that is produced results in an additional stability to the system. This propagation results in the radical becoming larger and lengthened. Therefore each longer, larger radical can react with its other radicals to produce a polymer that extends further. 1.4.3 Termination This chain reaction must eventually end. The instability of the radicals means that eventually they will collide and form a pair without making a new radical. This then becomes one of the final molecules of the polyethylene chain. This termination process is called coupling. 1.5 Metal and plastic As we move closer to the future we can see that plastics are slowly taking over the function of metals on our society. The reasons for this are pretty simple, plastics are cheaper to make in industry than metals. Forms of iron are renown for its strength in the field of life but iron oxidises and slowly degrades. Plastics are non-biodegradable, meaning that they are suitable for long term uses unlike metals that are prone to disintegrate. Plastics do not need a great deal of heat to be moulded into shapes but metals tend to have a high melting point, this is cheaper for industries because less energy is used to make their products. The strengths of plastics are shown in industry through fire resistant material, bulletproof vests and puncture resistant tyres, buildings etc. Plastics are also known now to be able to conduct electricity (although not to a degree of a metal like copper) by modifying polyacetylene by blasting the material with iodine vapour. Thus, eradicate an electron giving the material a positive charge, allowing the material to conduct electricity. This may eventually resulting in plastics replacing metals in the electricity components, making modern technological equipment, such as DVD players, computers, TVs etc., cheaper to produce. Plastics are currently manufactures from crude oil through the cracking process but now scientists have discovered producing biodegradable plastics using waste food. The process is considerably cheap and could revolutionise issues such as protecting our ozone (as waste food release methane gas) and also keeping landfills clear of pollution. 1.6 The forces between the molecules The physical properties of polyethylene are judged by its intermolecular forces. The intermolecular force is the force attracting one molecule to another, Van der Waals attractions or hydrogen bonds. The melting and boiling point of any molecule would depend on the potency of the intermolecular forces. Van der Waals attractions are more likely to occur with larger molecules and these attractions need more energy to split. Presence of hydrogen bonds will lift the melting and boiling points. When covalent molecular substances are heated, they usually melt at low temperatures. The molecules do not decompose but remain as separate groups of atoms. This implies that the forces within the molecules are strong but the forces between molecules are not very strong. The forces holding the molecules together are not the strong forces of attraction resulting from the sharing of electrons. Source http://www.nelson.com.au/chemistry/guide/unit1chemistry/s1b.htm Polymers are normally long chains of hydrocarbons, the longer the chain of molecules, the higher the melting and boiling points are. This is due to the increase in dispersion forces as the size of the molecule increases. Hydrogen and carbon are non-metals and in general covalent bonds are associated with two (or more) non-metals bonding. In this bond the electrons are shared between the atoms. Electronegativity is the power of an atom in a molecule to attract electrons to itself. Carbon has an electronegativity of 2.5 and hydrogen 2.2. Therefore the higher electronegativity of the carbon atom signifies that the bonding electrons are attracted to the carbon atom rather than the hydrogen atoms. As the carbon atom contains more electrons it becomes vaguely negative and the hydrogen becomes slightly positive. This negative and positive bond is known as polarised and each molecule is a polar molecule or dipole. The hydrocarbons can organise themselves to result in the negative end of one molecule to be supported with the positive end of the next molecule. This type of intermolecular bonding is called dipole-dipole attraction. Molecules that are not polar have the weakest forces of intermolecular bonding between them. These types of substances are observed to have the lowest melting and boiling points. These molecules are held together by dispersion forces, which result from instantaneous dipoles caused by the constant movement of electrons within the molecules. The strength of the dispersion forces increases as the number of electrons in the molecule increases. Source http://www.nelson.com.au/chemistry/guide/unit1chemistry/s1b.htm 1.7 HDPE ; LDPE High and low density polyethylene are created in conditions under that ethylene is polymerised, the molecules become attracted towards each other in the solids by Van Der Waals dispersion forces. 1.7.1 High-density polyethylene (HDPE) A linear polymer is the most basic form of polymer structures (HDPE) HDPE has generally no branched chains. This allows molecules to attach nearer to the molecule in a normal way, which is almost crystalline. This signifies that the dispersion forces are more effectual therefore the material is moderately stronger and has a higher melting and boiling point compared to LDPE. 1.7.2 Low Density polyethylene (LDPE) LDPE has many short branches besides the chain. The extra chains stop the other chains from lying closely together in a neat arrangement, dispersion forces are therefore lower compared to HDPE and the material is fragile and has a lower boiling and melting point. The density of the material is lower since the wasted space within the irregularly packed formation. 1.8 Thermosets Thermoplasts There are two distinguished features of plastic. These two are thermosetting and thermoplastic: * Thermoplastic (thermoplast) is a polymer that is cross-linked. When heated the cross links are softened and then the polymer has the ability to be moulded into different shapes. Once cooled the polymer returns to its original stability. This process can be repeated many times. Its is of great use in the plastics industry because materials that do not need great strength but personalised structure such as plastic bags can be made with ease. * Thermosetting polymers are significant for their strength and durability. They are vastly stronger but brittle compared to thermoplasts. They are, in general, linearly structured such as HDPE. When heated a thermoset is made substantially infusible or insoluble, therefore the polymer cannot return to its original shape, or the polymer experiences plastic deformation. 1.9 Youngs Modulus The Youngs Modulus is stress/strain at the elastic limit. It is basically a measurement of the strength of a material or how much the material yields for each pound of force. Deformation relates to the stress strain behaviour of a material. Stress can be seen as the pressure exerted onto a material. To calculate stress the formula stress = load/area of cross section is used. Strain is the deformation of a material in relation with stress, or the deflection of a material due to force. For this experiment I need to calculate these three. 2.0 Prelimary work Preliminary work is done to pre determine the needs for the final experiment to be a success. I shall cover issues such as safety and dimensions. 2.1 Dimensions of plastic strip To calculate the length and width of the plastic strip of bag that I would use for the experiment I had to test the maximum strength of different lengths and widths of bags. From pre-knowledge of structures of molecules, the wider strip should be able to withhold more weight and the longer bag should extend further. I will choose various lengths of the plastic strips and summarise the maximum load limit of the strips. To measure this limit I shall use the method chosen for the experiment. N.B: Throughout the experiments I shall be taking Gravity (g) as 10ms-1 2.1.1 Results Prelimary Experiment Max Load (N) Length (mm) Width (mm) 1 2 3 Average 100 10 8 8 9 8.3 150 10 10 9 9 9.3 200 15 12 14 12 12.7 200 20 16 15 16 15.7 250 20 17 17 17 17 2.1.2 Summary I conclude that the wider the strip of plastic, in general, the heavier it holds before breaking. The weight holders carry around 15 Newtons each therefore I shall use 200mm by 20mm for my experiment. I noticed that when I added more weights the width of the bag shortened as the extension became greater, this may affect the eventual outcome of the result. To indicate this later in the experiment I shall identify any anomalies. I also need to calculate the impact that I did when I added the weights on directly, later in the experiment I need to add the weights on Newton by Newton simultaneously. Calculating stress To calculate the stress I need to use the formula: Stress = Load Area of cross section First I need to calculate the area of the cross section. To do this I shall use the formula: Area = width ? thickness The cross section of the paper strip is: The thickness of the bag varied in each strip so I took the average of the thickness of the plastic strips from 6 samples using a micrometer. Average (mean) = ?x ?f Samples thickness: 1. 0.019mm 2. 0.022mm 3. 0.02mm 4. 0.018mm 5. 0.019mm 6. 0.02mm These results are fairly close together therefore I shall use these results, as they seem accurate. ? Mean = 0.019 + 0.022 + 0.02 + 0.018 + 0.019 + 0.02 6 Thickness = 0.0197mm If area = width x thickness Thickness = 0.0197mm Width = 20mm ? Area = 20 ? 10-3 (m) ? 0.0197 ? 10-3 (m) Area = 3.94 ? 10-7 m2 From these results I can calculate the stress. I shall go to the force of 17N because from previous knowledge I can say that the strip will be likely to break at this point or below. Load Applied (N) Stress = load/area of cross section (Pa) 0 0 1 2.5 x 106 2 5.1 x 106 3 7.6 x 106 4 1.0 x 107 5 1.3 ? 107 6 1.5 ? 107 7 1.8 ? 107 8 2.0 ? 107 9 2.3 ? 107 10 2.5 ? 107 11 2.8 ? 107 12 3.0 ? 107 13 3.3 ? 107 14 3.6 ? 107 15 3.8 ? 107 16 4.1 ? 107 17 (max) 4.3 ? 107 2.3 Prediction I predict that to the elastic limit the force will be proportional to length. Beyond the elastic limit the extension of the plastic strip will increase excessively. 2.3.1 Deformation This is because of deformation. Deformation is the modification of a material in response to force. The two types of deformation are elastic and inelastic (plastic). Elastic deformation is when a material returns to its original shape after the force has been applied. Inelastic deformation is the change of the original shape after a force has been removed. The reason of deformation is related to the bonds in the material. In deformation the bonds are being re-arranged. For example, when stretching a polymer the connecting covalent bonds are given energy and the bonds are stretched. The reason of inelastic deformation is that when the energy is applied to the bonds the cross links are moved then the object therefore changes its original shape. With a large enough force the bonds will break and the polymer breaks. 2.4 Reasons for testing The reasons for testing are: 1. Safety measurements. 2. Provide a basis for reliability. 3. Quality control. 4. Establish design ideas. 5. Meet the standards and specifications set by producers and standard agencies. 6. Verify manufacturing process. 7. Evaluate and compare against competitors products. 8. Establish history for new materials. 2.4.1 Costs of testing I need to research the cost of testing polymers to understand the importance of testing in the plastic industry. From Dr. Shastri I have found that the costs of testing polymers in industry are: Property (Single-point data) Cost Range Per Grade Average Cost Mechanical properties $780 $3120 $1500 Thermal properties $1030 $3270 $2000 Rheological properties $ 370 $ 650 $ 500 Electrical properties $1020 $1860 $1500 Other properties $ 170 $ 540 $300 $5800 Property (Multi-point data) [viz, creep, stress-strain] Average Cost $14,484 $93,140 This concluded that the testing of polymers at an industry level is out of my budget and time range. Therefore I must keep the experiment at, to a degree, a simplistic level. The large cost of the testing of polymers in the industry justifies the importance of the material to society. This relates with why that safety is needed when testing the material, I shall later resolve safety procedures. 2.5 Possible solutions to conduct this experiment in a laboratory are: 1. This method of conducting the stress relaxation test is needed with a pc to measure the length and force applied; the computer can then create a diagram of force/extension. I cannot execute this method because I have not got the right equipment and this experiment does not allow me to calculate the effects manually, which is what I wish to accomplish. 2. This experiment is capable of doing but I think that the material stretched along the table at such a length would mean I would have to use a long plastic bag which are hard to get hold of; apart from that this method would be acceptable for wire dimensions materials. 3. The ruler held into a fixed position means that there are less human errors in the measurements. The fixed position with the clamps and retort stand shows the stability and rigid structure of this method. This experiment allows me to manually draw up diagrams to calculate the Youngs Modulus. I am going to use experiment 3 to perform my experiment. Method to perform experiment 3 2.5 Apparatus Apparatus that I will need to conduct this experiment from the method I have chosen are: * Ballpoint pen. * Paper. * Metal wire. * Meter rule. * Micrometer. * Plastic carrier bag. * Retort stand. * Scalpel. * Safety (metal) ruler. * Scissors. * Sticky tape. * Wire clippers. * Cushion. * Weights. * Stop watch. A strip of plastic bag needs to be measured using a ruler accurately onto the bag with a pen. The marked out strip then needs to be cut using a sharp tool such as a scalpel and a safety ruler is needed for precision cutting and safety. The device I have chosen to hold the material to the weights and clamp is a metal wire that has been twisted. The wire will be 100mm long and then twisted into a circle like shape as shown in the diagram (left). The wire will be firstly looped into a ring of plastic from the bag; each side of the bag will be a fixed length for the wire to loop into. 2.6 Method 1. Set up the experiment as shown in the diagram. 2. Measure the length of the plastic bag between the two marked points using the ruler that is attached to the retort stand. 3. Add one Newton to the plastic bag. 4. Begin the stopwatch. 5. Once 5 seconds have passed measure the new length using the ruler. 6. Continue steps 3-5 adding one extra Newton each time until the plastic bag snaps. 7. Repeat the experiment 5 times for a fair test. The most important factor is always making accurate measurements. By checking the results of measurements more than once using a ruler and then obtaining an average will provide me with suitable evidence of recurring measurements therefore showing that they have been accurate. 2.7 Safety procedures Safety is one of the major factors of doing any experiment, or anything. The safety factors that I will take into hand in this experiment is: * Work in a large open area that will be sufficient to be a good distance away from people. * Keeping my body away from the weights and putting a cushion underneath the weights to soften the blow when the plastic strip breaks. * Take care when handling scalpels. * Use a safety metal ruler when cutting with the scalpel. * Using wire clippers to cut wire. * Use retort stand so weights are sturdily held. * Use weight holders so weights are held tightly together in an order. * Always be aware. 2.8 Fair test For the result of the experiments to be valid and contain fewer errors I need to suggest factors that will affect the result and then resolve them with solutions. The fair test factors that I have taken into practice in this experiment are: * Use the same plastic bag because of specimen variations. * The molecule variation in the bag, the bags handles might be made stronger than the bag, although this may not be true. * Do the experiment in room temperature, as the heat affects the atom bonds. * Keep the rate of loading the weights simultaneously because of impact strength. * Keep the ruler attached to the same place on the retort stand. * Repetitive. * Conduct the experiment five times to devise anomalies. * Use the same dimensions of plastic strips and wires. * Accurately measure with a ruler and avoid parallax errors. * Accurately cut the plastic strips with a sturdy ruler. Other factors that I have taken into place are the weight of the metal wire, but this was under a gram so it would not have affected my result by a lot and if I used the same wire consistently I could justify with the errors. 2.9 Creep Creep is a major factor when using heavier weights because the strip will gradually deform to relieve stress. This is why I need a fixed time to measure the extension when doing the experiment. 3.2 Conclusion My prediction was: I predict that to the elastic limit the force will be proportional to length. Beyond the elastic limit the extension of the plastic strip will increase excessively. My prediction in accordance to my results states clearly that this statement is true. Therefore my results are a success. The strips broke at different forces. This means that some of the strips may have been stronger than the other ones. This may have affected my results before the material reached its elastic limit because the bonds might have been stronger, also maybe because of human errors. The bonds in the different parts of the bags may have been engineered differently to suit its purposes i.e. the handle of the bag may have been made stronger than the body because of the force applied to it. I found that after the material reached its elastic limit the results became a little random. This may have been due to creep and the difficulty to measure the extension when the material is constantly going through deformation and the bonds are weakening making the material extend at a faster and easier rate. I have not included results after the elastic limit in my calculations because of this. The bag may also have contained additives such as colorants to produce colours on the bag; this may affect the bonds in the bag slightly and therefore affecting my results. I found the strip went through plastic deformation at around 10 N, which is equal to 1 kg. Bags are made to carry around 7 kg and the strip I cut was 1/10th of the bag, meaning that the strip cannot be justified as the strength of the bag as the shape of the bag differs from the strip and is stronger than the strip because of the way it is built. To summarise the results fairly I have created an averages of my results. I shall use the average results to do my calculations of the Youngs Modulus and strain energy. 3.3 Evaluating Graphs 3.3.1 Calculating Strain Energy When the strip is stretched we can say that energy has been applied to it, i.e. it extends (goes through deformation). The force extension graph can calculate the work done on the strip. Energy is measured in joules and is the area below the elastic limit on the graph. This energy is called work done and is the elastic potential energy, or the strain energy in the strip. Strain energy is the area underneath the force extension graph up to the elastic limit. ?This area must be a triangular shape because the line up to the elastic limit is straight. The area of a triangle = 1/2 base x height ? Strain energy = 1/2 f.x Where f is the force to produce the extension, x. Strain energy = 1/2 x 9 x 8 x 10-3 = 0.036 J 3.3.2 Calculating Youngs Modulus (E) Youngs Modulus is a measurement of the stiffness material. It is similar to calculating the gradient of the line up to the elastic limit. Youngs Modulus = Stress Strain = 2.5 x 107 0.096 = 2.604166667 x 108 Pa = 2.60 x 108 Pa (to 3 s.f) 3.4 Calculating the % errors for Strain Energy and E All experimental measurements have some degree of error associated with them. Physics Dept. New College Durham. There are systematic and random errors. A systematic error is when the method of measuring is always to large or to small. Such as a non-parallax error or when instruments such as the micrometer are not zeroed correctly. Random errors are when repeated results have different outcomes. To avoid this the experiment can be repeated and then take an average from the results. The formula used to calculate error = ? Smallest division Height gained Error in 100g masses = ? 0.1g ? ? 1.0 x 10-4kg Error in metre rule reading = ? half the smallest division of the rule. = ? 0.5mm Since a measurement is the difference between 2 readings error = ? 1mm ? ? 1.0 x 10-3m Error in vernier reading = ? half the smallest division = ? 0.0005mm Therefore the measurement error (2 readings) = ? 0.0001mm ? ? 1.0 x 10-6m 3.4.1 Strain Energy Strain Energy = 1/2 x load x extension Elastic Limit = 0.9 kg and 8 x 10-3 m % Error in mass (9 x 100g) = 9 x 1.0 x 10-4 kg x 100 9 = ? 0.1% % Error in extension (metre rule) = 1.0 x 10-3m x 100 8 x 10-3 m = ? 12.5% To obtain the total error for strain energy, add the % errors = ? (0.1% + 12.5%) = ? 12.6% Strain energy = 1/2 f.x = 1/2 x 9 x 8 x 10-3 = 0.036 J ?Strain energy = 0.036 J ? 12.6% = 0.036 J ? 0.00454 J 3.4.2 Youngs Modulus Youngs Modulus = Stress Strain = (Force/area of cross section) (Extension/original length) = Force/area of cross section x original length/extension = (Mass x gravity/thickness x width) x (original length/extension) Mass % error = ? 0.1% Material thickness = 0.0197mm ? 0.0197 x 10-3m Material width = 20mm ? 20 x 10-3m Original length (between lines) = 100mm ? 100 x 10-3m Extension = 8mm ? 8 x 10-3 m at elastic limit Material thickness % error = 1.0 x 10-6m x 100 (Vernier) 0.0197 x 10-3m = ? 5.076142132 ? ? 5.08 (to 3 s.f) Width % error = 1.0 x 10-3m x 100 (Rule) 20 x 10-3m = ? 5% Original length % error = 1.0 x 10-3m x 100 20 x 10-3m = ? 0.5% Extension % error = 1.0 x 10-3m x 100 8 x 10-3m = ? 12.5% For the total error, add the % errors = (mass + thick + width + ori length + extension) = ? (0.1 + 5.08 + 5 + 0.5 + 12.5) = ? 23.18% ?Youngs Modulus = 2.60 x 108 Pa ? 23.18% = 2.60 x 108 Pa ? 60268000 Pa = 2.60 x 108 Pa ? 6.03 x 107 Pa (to 3 s.f) 3.5 Evaluation The experiment conducted allowed me to calculate the Youngs Modulus using a carrier bag, the method I used was suitable to the objective of measuring force against extension (the investigation). From my results and graphs I can see that there were no spurious readings in the investigation. Therefore my experiment was a success. The problems of this experiment was the cutting of the plastic bag as due to the lack of friction the plastic bag was not held properly onto the work surface. I tried to resolve this by embracing the carrier bag onto the work surface whilst I cut it but this was still difficult as the bag still moved. When the strip had a force applied its width reduced and the strip became compact into a wire dimensional shape. I would have preferred f I was able to hold the original shape intact when adding the weights. I did try other methods, such as replace the wire with a pencil and hold the weights on each side but this meant that the weight addition was going up by 2N instead of 1N simultaneously. Also putting on the 2 weights at the same time was difficult because of balancing the pencil, this meant that creep came into affect and I it was hard to record measurements at a fixed time. I would have preferred to use a PC to help me record my results, as this would have reduced the human errors and recorded the results more accurately than I could have. But the costs of using a computer and setting it up was time consuming and would not have correlated with the time I was given to conduct this experiment. The strain energy and Youngs Modulus % errors were both above 10% and this is quite a high figure when trying to measure accurately. If I used a computer this would have reduced my errors and made my measurements accurate. If I were going to extend this testing into measuring hardness, viscosity or ductility then I would have re-done the experiment using a PC. At a more advanced level plastic deformation is caused by the motion of dislocations, which involves the breaking and reforming of bonds. This can be seen as a random procedure because the force applied would have to be done on the same material with the exact structure and the force applied in the exact place. As carrier bags are made in masses I doubt that the structures are exactly the same. Therefore it would be pointless for me to have measured beyond the elastic limit.