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.

Authors Avatar

Plastic Bags

Introduction

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  through the machine as they are separated and sealed as required.

Join now!

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, ...

This is a preview of the whole essay