The Life Cycle of a Plastic Bag

By: Riley O'Hearn

How plastic bags are made

Traditional plastic bags are usually made from polyethylene, which consists of long chains of ethylene monomers. Ethylene is derived from natural gas and petroleum. The polyethylene used in most plastic shopping bags is either low density or, more often, high density. Color concentrates and other additives are often used to add tint to the plastic. Plastic shopping bags are commonly manufactured by blown film extrusion.

Step 1:

An extruder heats polyethylene plastic resin pellets to around 500 degrees Fahrenheit, enough to melt the pellets. A screw inside the extruder forces the molten plastic through the machine and pushes the material through a die that controls the thickness of the product. Air forces the emerging plastic film into a bubble that travels upward about three stories in a cooling process. After pinching out the air and flattening the bubble, the film is cut to size and wrapped on a spindle.

Step 2:
A conversion department unwraps the roll of film and slices it with a heated knife that both seals the sides of the bag and cuts it to size. The conversion department also adds any special characteristics needed for a completed bag. Dies cut out handles, wheels produce gussets, and zippered seals get attached with heat or by ultrasonic means. Any printing may be done after the bags have been converted, or in a separate department between extrusion and conversion.

How It's Made Plastic Bags

How plastic bags are used and for how long

Plastic bags are used to hold food from your local grocery store and even common items like clothing and accessories you buy when shopping at the mall. For every one of us, 216 plastic bags a year are handed out. A typical free supermarket bag is used for an average of 20 minutes before it is thrown away.

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What happens when plastic bags are no longer needed?

Plastic bags have only been around since the Thirties, so no one knows how long they last; however, scientists estimate they take 400 to 1,000 years to vanish. Some are designed to turn into carbon dioxide, water and compost within a month or two . Chemicals in some bags, particularly the inks used in printing, can leak and cause poisoning or turn into noxious compounds if burned.

In the oceans, they can survive intact for years. A recent Greenpeace report found that one remote area, called the Pacific Gyre, a whirling current, contained more than a million items of plastic microdebris in every square kilometre of ocean surface. Plastic bags and other waste kill a million sea birds and 100,000 animals such as whales, dolphins, turtles and seals, each year. Once the animal's body has rotted, the bag is released back into the sea, to kill again and again.

Ways to Reuse and Repurpose Plastic Bags

-Keep bags in the glove compartment to use as trash bags on road trips

-Donate them to food pantries, libraries, day-care centers, or hospitals that take them

-Take them back to the grocery store for reuse in bagging your groceries

-Keep plastic bags around the house to replace trash can liners in the bathrooms

-Use as a lunchbox to carry lunch in for school

-Recycling plastic bags allows it to travel back to the factory to melt the components involved in making it and make more plastic bags

Impacts of the three R's (Reduce, Reuse, and Recycle)

Reduce the amount of plastic bags you use as it will help to prevent
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Buy reusable bags to use every time you go to the store rather than using plastic bags
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Plastic bags are one of the most widespread forms of litter. In fact, the not-for-profit Center for Marine Conservation identifies them as one of the top types of trash collected during coastline cleanups. They are discarded in parks and on highways, get caught in trees, clog gutters and sewers, and even pose threats to ocean life that mistake them for food. But the most significant problem with discarded plastic bags-and the reason they are so prevalent as litter-is that they arenot biodegradable.
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Works Cited

Andrews, Gianna. "Plastics in the Ocean Affecting Human Health." Geology and Human Health. N.p., 16 Sept. 2013. Web. 26 Apr. 2015.

Bedolfe, Sarah. "10 Easy Ways to Use Less Plastic." One World One Ocean. One World One Ocean, 11 Sept. 2012. Web. 26 Apr. 2015.

Emily. "Benefits of Cloth Bags." Use Cloth, Not Plastic! Blogspot, 2 May 2010. Web. 26 Apr. 2015.

"Great Pacific Garbage Patch." National Geographic Education. National Geographic, n.d. Web. 26 Apr. 2015.

"Plastic Bags Pollution – Effects and Solutions." Green Living Bees. N.p., 9 Dec. 2012. Web. 26 Apr. 2015.

"Tips To Use Less Plastic." Green Education Foundation. Green Education Foundation, n.d. Web. 26 Apr. 2015.

Watkins, Rebecca. "Stop Using Plastic: 21 Ways to Quit." Natural Mothers Network. Natural Mothers Network, n.d. Web. 26 Apr. 2015.

"Why Green?" Green-O-Bag. Green-O-Bag: The Reusable Bag Company, n.d. Web. 26 Apr. 2015.

"Why Is Plastic Harmful for Environment?" Kinooze. Kinooze, 7 Nov. 2012. Web. 26 Apr. 2015.