I am investigating which supermarkets have the strongest plastic bags; I have tested this out in an experiment. I will also be researching whether plastic bags are good or bad for the environment and how they can be replaced or used differently. It is estimated that we use over 500 billion plastic bags worldwide every year, which is nearly 1 million bags used every minute. In the UK It is estimated that we use 10 billion which is about 167 bags per person.
They are very controversial as they take a very long time to break down and only 1 in 200 plastic bags in the UK are recycled; they pose a choking hazard for wildlife and children, plastic contains a lot of chemicals and some found could cause cancer and people find that there are many other replacements like using paper bags instead. Plastic is an organic substance consisting of large molecules called polymers. It is distilled from wood, coal, oil and even natural gas by chemicals such as hydrogen, nitrogen, oxygen and carbon.
Other chemicals present in plastic may include chlorine, sulphur, silicone and fluorine. Plastic bags are made in a number of ways and for a number of purposes; each plastic bag is made of a polymer. Polymers are large molecules that contain lots of a chosen repeating monomer. Plastic bags are made from the monomer ethylene (ethene). These ethylene molecules are made into polyethylene. Polyethylenes are generic in that they include all ethylene that has been polymerized, but they may have other characteristics.
Three polyethylenes are identified as being used in the manufacture of plastic bags because of their density, low-density polyethylene, linear low-density polyethylene, and high-density polyethylene. Branching, replacing the polymer chain with other forms or variations of the monomer can further change the characteristics of the plastic. Highly branched polymers make thinner plastic. Branching also affects tensile strength and clearness or crystallinity of the plastic.
The more branched the plastic bag, the less ability there is to see through it, and the easier it tears. Plastic bags are made out of polyethylene, which is a thermoplastic commodity and is used a lot in consumer products, as over 60 million tons are produced worldwide every year. It is a polymer consisting of long chains of the monomer ethylene. High density polyethylene is a polyethylene thermoplastic made from petroleum. It takes 1.75 kilograms of petroleum, in terms of energy and raw materials to make one kilogram of high density polyethylene.
This compound is used to make plastic bags. Low density polyethylene is a thermoplastic made from oil. Plastic for bags is created by a blown film extrusion method. The blown film extrusion process is a tubular process. The resin is delivered to the bag manufacturer in pellets. The pellets are placed into a hopper, melted and then extruded into a tubular form through the force of cool air. Cool air is forced into the tube until it reaches the correct size needed.
The tube of plastic is now flowing upward through the cooling tower. After the plastic has cooled, it is guided away from the cooling tower and flattened on a roller. The bags continue to travel through the machine as they are separated and sealed as required.
Most plastic bags are thrown away, often after a single use but sometimes they are re-used. Recycling of plastics after being used is possible, but plastic bags, in particular, are rarely recycled. According to the UK-based Ban the Bag campaigning group, 0.5% of plastic bags are recycled. Standard plastic bags may take between 500 and 1000 years to decompose, however, these figures are actually only estimates because plastics have not existed for long enough for the precise decomposition time to be measured.
Additives have been developed that allow plastic to degrade and biodegrade within a few months in landfill, as opposed to an estimated 500-1000 years for non-degradable plastic. Plastics made with these additives are called oxobiodegradable. However, some argue that oxobiodegradable plastics give out more to global warming as they release their carbon as carbon dioxide and methane far more quickly than plastics in landfill. Method
3 plastic bag from 3 different supermarkets
1. Set up apparatus as shown in the diagram below.
2. Put the 100g masses in the plastic bag until it can’t take any more 3. Repeat this twice more for the same brand of plastic bag
4. Repeat all the steps for the other two brands of plastic bags
The graph shows that Waitrose plastic bag is the strongest and can hold 12.7kg on average. The Somerfield bag is the weakest and can only hold 11.1kg on average and the Tesco plastic bag can hold 11.5kg on average. Before averaging the results the Tesco plastic bag was the strongest when it held 13.5kg on the first time but the third time it only held 7.8kg and the second 13.2kg. For the Somerfield plastic bag the first time I tried out the test it held 10.7kg, the second time the plastic bag held 11.6kg and the third time it held 11kg. On the Waitrose plastic bags the first time it held 12.7kg, the second time it held 12.8kg and the third time it held 12.7kg.
The supermarket which had the similar results before I averages them was the Waitrose plastic bag as all the results on the three times I tested them they all turned out to be quite similar. The Tesco bag the first two times I did the test I got similar results but the third time must have been an anomalous result as the difference between the first time I did it and third was 5.7kg which is a big difference. The Somerfield bags were mostly all the same on the three times I did the test.
I made my experiment valid by making sure that I kept the 100g masses in the plastic bags for the same amount of time each, I only changed one thing and it was the fact that I used different brands of the plastic bag, I made sure that I was putting the masses in the plastic bag from the same height, and that the same person was putting the masses into the plastic bag. I could have made the experiment more valid if I had made sure the bags were not used before my experiment, as the use of it might have made the bag weaker and that might have been why I had an anomalous result, and if I had made sure the bags were all the same size and shape as this might have impacted my results.
I made my experiment reliable as I repeated the test three times, I looked for anomalies and I averaged the results and put them into a graph. I could have maybe improved the reliability of my results if I had repeated it more times and comparing my results with someone else’s to see if we are getting the same.
Why they are good?
Plastic bags have so many practical uses. There are too many uses of plastic bags to be able to get rid of them. Plastic bags are used as bin liners you cannot replace bin liners with another type of bag it is not efficient and even worse for the environment. Banning plastic bags would just see paper bags clogging up our waterways. Plastic bags are handy to have and are an important part of our lives. Most plastic bags are made from a plastic called polyethylene; it is good, because it can, in its raw form, be changed to make any colour, shape, form or size desired which makes it inherently versatile.
It is also very durable and watertight; making it an ideal carrier of heavy good, although it can’t be recycled it can be re-used over and over again. Plastic bags can be melted and remoulded, and be made into plastic lumber in order to be used on things such as park benches and in fencing material. They also emit lower levels of both solid waste and greenhouse gases, and any plastic that goes un-recycled is capable of being burned in order to generate electricity, which can contribute to lowering sulphur emissions produced by burning fossil fuels like coal.
Some people believe we can replace plastic bags with paper bags, as they can be recycled, but in fact it takes more than four times as much energy to manufacture a paper bag as it does to manufacture a plastic bag. Paper come from trees, which means the impact of paper bag production on forests, is enormous. In 1999, 14 million trees were cut to produce the 10 billion paper grocery bags used by Americans that year alone. Paper bag production delivers a global warming because forests which are big absorbers of greenhouse gases have to be cut down, and then the manufacturing of bags produces greenhouse gases.
Paper also creates pollution; it creates 70% more air pollution and 50 times more water pollutants than plastic bags. Plastic bags are also better than paper bags; it takes 91% less energy to recycle a pound of plastic than it takes to recycle a pound of paper. Also current research demonstrates that paper in today’s landfills does not degrade or break down at a faster rate than plastic does, because nothing completely degrades in modern landfills because of the lack of water, light, oxygen and other important elements which are needed for the degradation process to be completed, a paper bag takes up more space than a plastic bag in a landfill.
Some people are thinking of banning plastic bags, but this would cause people to lose their jobs. The production of plastic bags is a big industry. There are factories which produce the bags and distribute them. There is the fact that these factories may cause pollution, but they also have a vast amount of staff policing the production and if people ban plastic bags then these people will lose their jobs.
Some supermarkets are also considering for charging for plastic bags and some like Tesco provide points if you re-use them but some people believe that they are not that bad and it is unfair for supermarket chains to profit from something they get for free. Nearly all supermarkets get provided plastic shopping bags for free. It is really not fair for supermarket chains to profit money for a bag when they are used in very large numbers and they get the bags for free.
Why some people think they are not so good? Some people believe that plastic bags for use by consumers in supermarkets and other stores should be made illegal, as In the UK alone, over 13 billion plastic bags are handed to consumers each year. Plastic bags are responsible for the deaths of huge numbers of marine species, who mistake the bags for food. They believe that it is hugely wasteful, massively unethical, and potentially deadly to continue using plastic bags. Most of the polyethylene that goes into making the vast majority of plastic bags is derived from natural gas-which is a non-renewable, Plastic bag production also uses almost 10 percent of the world’s annual oil supply.
Only 3.5 percent of this number are recycled. This means that much of the planet’s natural resources are being used to produce plastic bags that many people’s uses for it are unnecessary. They are non- biodegradable, meaning that they cannot be broken down to assume their natural, organic state. Even under ideal conditions, they would photodegrade over a periods of between 500-1,000 years.
This means that plastic waste stays in our overall ecosystem for a very long time, and also means that every bit of plastic produced since its inception over 50 years ago is still with us, which makes it a lot of plastic waste. Plastic bags also litter streets, as not only do plastic bags fill up our landfill sites where they will remain forever more, but people throw them into the streets. They accept plastic bags when they do not need to and once out of the shops take their items and litter the streets with the unwanted plastic bags. Throwing plastic bags could make the soil unfertile (soil pollution).
This is very bad, we need fertile soil because it helps plants to grow, which is our food. Animals also need soil cause it make plants to grow and animals eat plants. We can say they indirectly depend on soil. burning plastics causes very polluted gases which could make our lungs weak on breathing them, also can cause many lungs diseases like asthma. Daily more than 5 tons of plastic bags are thrown away. Animals can get caught in them, motor accidents are caused, and many end up in trees. Countless plastic bags end up in the ocean and cause harm to the marine wildlife. Many marine animals and birds mistakenly ingest plastic or become entangled and choke in plastic bags that are floating around.
Some turtles mistake plastic bags for jellyfish and accidently eat them, it is estimated 100,000 marine mammals die each year because of plastic litter in the ocean in the North Pacific. In some countries like India, cows are mistakenly ingesting plastic bags on the streets as they are scavenging for food and end up choking or starving to death, as the plastic cannot be digested. Plastic bags don’t just kill animals they can also kill humans, as some young babies and children could suffocate on them, in other cases if a parent doesn’t want their child they can suffocate the baby themselves and kill them.
If supermarkets start charging for plastic bags it could be a good thing, as it would deter people from using them in large amounts. If each plastic bag cost 10p, then people would not use them in large amounts because they are paying. If someone shopping twice a week, using six plastic bags each shop, and the bags cost 10p each, they would realize that that would cost over £60 a year so they would either not use as many, or they would start to reuse plastic bags. If everyone started to re-use plastic bags while they were shopping then, then plastic bags wouldn’t be made in large numbers, and this way they wouldn’t need to be replaced because people are using less.
I think that plastic bags are ok as, some people believe that replacing them with paper bags or bags made out of cloth, or just banning plastic bags. I think that banning plastic bags would save plastic, but add to the environmentally harmful production of paper and cloth. We do still need something to put shopping or rubbish in and if we stop using plastic for the bags, we’ll start using another resource which will be bad for the environment such as paper and as I stated above that’ll be worse for the environment than plastic bags.
I think that we could replace plastic bags, but with something that is environmentally friendly, it wouldn’t harm the environment and then we would use less plastic bags. Or I think someone should invent a bag which is like a plastic bag but one that does not use up natural resources or harms the environment or kills people to keep everyone happy, something that is also biodegradable so even if it does get thrown away it will degrade in the landfills fast.
Biodegradable- Capable of decaying through the action of living organisms. Branching- A division or subdivision of the stem or axis of a tree, shrub, or other plant. Decompose- To separate or resolve into constituent parts or elements. Degrade- To break down (a compound, especially an organic hydrocarbon). Ethylene- A colourless, flammable gas, C 2 H 4 , having a sweet, unpleasant odour and taste, the first member of the ethylene series, usually obtained from petroleum and natural gas: used as an agent to improve the colour of citrus fruits, in the synthesis of polyethylene, ethylene dibromide, ethylene oxide, and other organic compounds, and in medicine chiefly as an inhalation aesthetic.
Excursion- The displacement of a body or a point from a mean position or neutral value, as in an oscillation. Molecules- A quantity of a substance, the weight of which, measured in any chosen unit, is numerically equal to the molecular weight; gram molecule. Monomer- A molecule of low molecular weight capable of reacting with identical or different molecules of low molecular weight to form a polymer. Pollutants- Any substance, as certain chemicals or waste products, that renders the air, soil, water, or other natural resource harmful or unsuitable for a specific purpose.
Polymers- A compound of high molecular weight derived either by the addition of many smaller molecules, as polyethylene, or by the condensation of many smaller molecules with the elimination of water, alcohol, or the like, as nylon. Thermoplastic- Soft and pliable when heated, as some plastics, without any change of the inherent properties. Unfertile- Incapable of growth or development, as seeds or eggs.
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http://www.ehow.co.uk/facts_7631606_pros-cons-paper-bags.html http://www.ehow.co.uk/list_5899174_pros-cons-recycling-paper.html http://answers.yahoo.com/question/index?qid=20080907174427AA1uvMZ http://www.suite101.com/content/environmental-dangers-of-plastic-bags-a123185 http://thinkgreen.ralfengel.com/pollution/dangerous-plastic-bags http://wiki.answers.com/Q/Are_plastic_bags_dangerous
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