Gayla Bacus
SLCC: Chem 1120
Elementary Bio-Organic Chemistry
Instructor: Mary Alvarez
Plastics: Miracle or Menace?
Where would we be without plastics? How could we function without plastic bags, plastic milk jugs, the plastic components necessary for our laptops? Plastic has become a necessary part of our everyday lives. In little over 50 years, plastics has become a multi-billion dollar industry. The use of plastic has transformed the fashion, technology, aerospace, and medical industries, to name a few. In 1967, on the cusp of the plastics explosion, a Hollywood movie, The Graduate, summed it up in one brief exchange between Dustin Hoffman's young Benjamin Braddock and Walter Brook's Mr. McGuire:
Mr. McGuire: I just want to say one word to you… just one word.
Benjamin Braddock: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin Braddock: Yes, sir, I am.
Mr. McGuire: Plastics.
Plastics were the way of the future, and anyone who was in the know could see it coming. “Better Living Through Chemistry” became the slogan to sell a multitude of products and a slogan for a generation that was beginning to embrace plastics in all aspects of their lives. Everything from transistor radios to go-go boots, vinyl couches, plastic ovoid shaped kitchen tables and chairs, and mood lighting. Plastic was suddenly everywhere in the modern home and it was here to stay.
Plastic is, by definition, “any material that is capable of being shaped or molded” (Goebel). These materials may be natural or man-made. All plastics are polymers, but not all polymers are plastics. We're surrounded by naturally occurring polymers in the form of proteins, starches and DNA. Natural polymers such as tortoise shells, shellac, amber, tar, and latex, have been processed to form hair ornaments, gum, celluloid and vulcanized rubber. Rubber has been produced since the 1800's and used extensively for everything from tennis shoe soles to children's toys and automobile tires. Alexander Parkes is credited for making the first man-made plastics, which he introduced as Parkesine at the 1862 Great International Exhibit in London ("The History of Plastic"). This material could be carved into a variety of useful shapes. The product never caught on due to the high cost of the raw materials needed to manufacture it. A few years passed until a billiards craze reduced elephant herds with the demand for ivory and a suitable replacement was required. John Wesley Hyatt rose to the challenge of an alternative billiard ball and invented the first thermoplastic. It was based on collodion and camphor, a substance that could be molded under heat and would retain its shape when cooled – celluloid was born. Celluloid became the first flexible film and brought in the age of the motion picture industry. Around this time, other polymers were developed using natural products as their base. Rayon was developed in 1891 as an alternative to silk by Louis Marie Hilaire Bernigaut. In 1913, Dr. Jacques Edwin Brandenberger used this silk worm product (also known as viscose) to develop cellophane, a flexible water-proof packaging material. During the same era, the first all-synthetic plastic was invented. In 1907, Leo Baekeland, a New York chemist, developed a resin that would take the shape of its container when hardened and “would not burn, boil, melt, or dissolve in any commonly available acid or solvent”("The History of Plastic"). The applications for a product that was lightweight, durable, electrically resistant, heat resistant, and won't crack or fade were numerous. Bakelite became the pioneer material of the plastic revolution. Bakelite was used extensively in weapons during World War II. Domestically, it was used in electrical insulation and is still used in this application today. Bakelite ushered in the “plastics craze” - the next step in the development of plastics, as innovation moved into the chemistry labs of major manufacturers. As the structures of plastics were better understood , variations could result in new products with new applications. DuPont was an early adopter of the new technology and was a hotbed of early innovations. During the 1920's and 30's under the leadership of Wallace Hume Carothers, a Harvard chemist, DuPont developed nylon which quickly replaced natural fibers in everything from toothbrushes to women's stockings. Other natural fibers and products were replaced by DuPont innovations in the 1940's, such as neoprene, acrylic, polyethylene and Teflon.
The science behind the innovations is relatively simple. Plastic is a polymer made up primarily of hydrocarbons (hydrogen and carbon molecules), “links” joined together to form straight or branched “chains”.This joining process is called polymerization. A simple polyethylene polymer is shown below:
(“History of Polymers and Plastics for Teachers”).
Although many polymers are made of simple hydrocarbons, other molecules may be involved. PVC (polyvinyl chloride) contains chlorine. Nylon has both nitrogen and oxygen elements in its structure. Silicone, phosphorous, sulfur, and fluorine are also commonly found in plastics. Inorganic polymers have silicone or phosphorous backbones instead of carbon
.
Polymerization can occur through addition or condensation polymerization. In addition polymerization, a double bond is broken and multiple monomers join together to form a chain. Acrylic, polyethylene, and polystyrene are formed though addition polymerization. Most addition polymers are thermoplastic, which are easily recyclable and make up the majority of plastics used today. Condensation polymerization results in a small molecule being lost from the original monomer as they are joined together.
Nylons, urethanes, and some polyesters are condensation polymers (Freudenrich). As the monomers join together, the side group will line up on one side of the backbone or the other. In most cases (90 – 95% of the time), the side groups will all be arranged on the same side of the backbone. This formation is called isotactic and is depicted in the polypropylene molecule diagramed below:
(“History of Polymers and Plastics for Teachers”).
The arrangement of polymer chains in relation to each other can have a big impact on the properties of the plastic. Chains that have an amorphous arrangement are packed loosely together like a bowl of spaghetti. Polymers with such an arrangement are generally transparent, such as plexiglass and saran wrap. Other polymers are arranged in a crystalline pattern. Crystallinity affects the melting point and translucence of the end product. The higher the crystallinity, the higher the heat resistance and strength of the final product. This processing is highly regulated to control the amount of crystallinity desired depending on the intended use of the plastic.
The use of plastic has come a long way since the first introduction of Bakelite in 1907. Since 1976, plastic has become the most used material in the world ("The History of Plastic"). From the time you get up in the morning and push the plastic switch on your alarm clock, until the time you go back to bed at night to lay your head on a polyester-stuffed pillow, you are surrounded by plastic. They have made our houses warmer and more energy efficient by the use of insulation, vinyl siding, and vinyl windows. We drive cars that are lighter, more fuel efficient and safer, due to the average 332 pounds of plastic in each car. They have made food products safer through better packaging and sealing of containers, accounting for 40% of all plastic manufactured in the form of product packaging. While 15% of plastics are used in products at home, many plastic products are used in the medical field, saving lives with disposable syringes, IV bags and tubing, orthotics, and even heart valves and joint replacements (“Plastics in Daily Life”). Because of the high heat resistance of plastic, it has been used extensively in the aerospace industry for rocket boosters and re-entry shields. Its strength and lightweight characteristics have changed the aeronautics industry, beginning with its introduction into military aircraft in WWII. Other characteristics, such as durability and resistance to corrosion, has led the construction industry to fully embrace plastic products as a primary building material. The construction industry is the second largest consumer of plastics (behind product packaging). Everything from pipes to plumbing fixtures are now made out of plastic. Possibly the largest impact to our daily lives, the use of computers, is made possible by plastics. Its thermal and insulating abilities allowed computers to evolve into miniature chips on circuit boards that still provide a well-insulated and dust free environment, paving the way for our personal computers and hand held electronic devices (“The Benefits of Plastic”). Even with advances in other industries, the innovations in technology and electronics would not have been possible without the amazing breakthroughs in the production of plastics.
Looking to the future, there are many exciting applications for plastics on the horizon. HP is working on flexible screens for TV's and computers that could theoretically, be rolled up and put in your pocket. Single layered plastic semiconductors are making it all possible. What was once thought of as sci-fi and futuristic is now becoming a reality. Such is the case with nanotechnology. Microchips the size of postage stamps with amazing storage capacities are now possible, and smaller means faster. Plastic nanotubes are compact and durable and have the ability to conduct electricity. They are being used to create conductive paints, coatings and caulks that have important uses for the automotive and aerospace industries. In addition to their conductive attributes, paints reinforced with nanotechnology would be scratch and dent resistant – a huge bonus on that new car! Nanocomposite foams could replace carpet padding, food packaging, disposable diapers, and insulation. The benefits of nanotechnology include smaller, lighter, less expensive to manufacture and less material required for production (“The Future of Plastics and Nanotechnology”).
Although there is no argument that the development of plastics has been beneficial to our lives, there is definitely a dark side to the modern marvel. Many studies are ongoing, regarding the leaching of chemicals into our food or water from the plastic containers they're stored in. Because of the properties of durability, resistance to melting, dissolving, or degrading, the disposal of plastic has become a huge problem. Pollution from landfills, groundwater contamination, ocean and air pollution are all becoming major issues due to our dependence on plastics (Mackiewicz 9).
The danger of chemicals leaking into food or drink from its plastic container revolves mainly around the use of BPA (Bisphenol A) in plastic bottles or food storage containers. These containers are usually marked with the plastic recycling code “7” which identifies it as a miscellaneous plastic. BPA has been shown in studies to disrupt hormones during development, as well as possibly causing prostate cancer, obesity, and Type 2 diabetes (Burcher). Another plastic with controversial health risks is the class of phthalates (marked with the plastic recycling code “3”). Their use has been linked to health problems in developing sex organs in male infants, abnormal brain development due to endocrine disruption, precocious puberty and autism. PET (Polyethylene) is found in most water and soda bottles, but is suspected of being a human carcinogen. These bottles are marked with the plastic recycling code “3” (“Adverse Health Effects of Plastics”). There is a lot of debate surrounding the possible health effects of plastics. Because their use has only become widespread in recent years, there is not enough historical data to support or deny some of the claims. It is up to the consumer to use these products judiciously.
The greatest attribute of plastics (their durability) also makes them very difficult to dispose of. The annual consumption of plastic has skyrocketed from 5 million tons annually in the 1950's, to over 100 million tons today, and yet it is estimated that only 7% of all plastic waste is currently being recycled. Each American consumes an average of 62 pounds of plastic each year. Approximately 250,000 drink bottles are thrown away every hour in the U.S. Plastic bottles can make up more than 50% of the recyclable waste found in landfills today. That's a depressing statistics when armed with the knowledge that 25 of those bottles could produce a fleece garment and the demand for recycled plastic far exceeds the supply. Only 27% of water and soda bottles are recycled. When left in the landfill, it can take 700 years for the bottle to decompose (“Recycling Statistics and Facts”). Here are a few interesting statistics on our plastic consumption:
- Number of plastic bags used worldwide each year: 4,000,000,000,000 to 5,000,000,000,000.
- Amount of oil used annually to produce plastic bags: 17,200,000,000 to 21,500,000,000 gallons.
- Number of plastic bags used by Americans each year: 110,000,000,000.
- Amount of plastic bags recycled in the United States in 2006: 2%.
- Amount of plastic used worldwide every year just to bottle water: 1,500,000 to 2,700,000 tons.
- Number of plastic water bottles sold in the United States in 1997: 4,000,000,000
- Nearly eight out of every 10 bottles will end up in a landfill.
(Perkins).
Dumping, run-off, and wind can cause this plastic trash to find its way to rivers and ultimately out to the oceans where it creates a deadly problem. Today there is an estimated 100 million tons of plastic in our oceans and makes up 80% of all marine debris (Marine Debris). Ocean currents carry the debris to areas in the ocean called gyres, where the currents are weakest. There, the trash accumulates to form a floating garbage dump. The Great Pacific Garbage Patch (also known as the Trash Vortex) is twice the size of Texas and consists of approximately 3 million tons of plastic. This trash kills an estimated 100,000
seabirds and 1,000,000 sea creatures each year. Much of the plastic is in the form of nurdles, or mermaids tears, which are a small plastic bead used in the production of plastics, but can also be caused by plastics breaking down through physical weathering. Not only are these small pellets harmful in themselves, but due to their chemical properties, they act as sponges for DDT, PCB's and other hydrophobic toxins that accumulate on their surfaces. Creatures that ingest these plastic beads, ingest toxins at rates of up to 1 million times higher than the surrounding seawater (Marine Debris). Many organisms, such as krill, simply choke on them and die. Others have their immune and reproductive systems disrupted by the endocrine disruption effect of the plastics themselves. Wiping out large krill populations at the bottom of the marine food chain can have a huge impact on all marine life.
The primary solution to removing plastics from the landfills and ocean dumping, is to reduce, recycle or reuse materials. Many major metropolitan areas now have curbside recycling programs. More Americans are recycling their consumer waste. There is much confusion about recycling, as all plastics are marked with a plastic recycling code, but not all of them can be recycled in all areas. Technology exists to be able to recycle all types of plastics, but it is not always profitable to do so.
Soda and water bottles are one of the most recycled products at 27%. They are also the most sought after recyclable product as demand often exceeds the supply. Plastic shopping bags and thin packaging films are recycled at a rate of 12%. Each recycling product code corresponds to a different type of plastic which may be recycled using different methods. #1 Polyethylene Terephthalate is commonly used for liquid containers and can be recycled into new containers, carpet, clothing, and autoparts. #2 High Density Polyethylene is used in milk containers, grocery bags and other liquid containers and can be recycled into drainage pipe, benches, floor tiles and synthetic lumber. #3 Polyvinyl Chloride is found in bottles, wire insulation and building materials and is recycled into decking, paneling, and flooring. #4 Low Density Polyethylene is found in squeezable bags, frozen food bags, insulation, and carpeting and can be recycled into trash cans, landscaping ties, and shipping envelopes. #5 Polypropylene is found in food and medicine bottles and can be recycled into signal lights, battery cables and bike racks. #6 Polystyrene is found in plates, cups, and carry out containers and can be recycled into thermal insulation, light switches and foam packaging. #7 Other is generally a combination of other resins and can occasionally be recyclable as synthetic lumber (Recycling Symbols(US)). The US recycled 2.4 billion pounds of plastic bottles in 2008 and 830 million pounds of plastic bags. More businesses are involved in plastics recycling as it becomes a more profitable venture (over 1,600 businesses in the US today) (Killinger 1). There is even a growing interest in the possibility of mining existing landfills for plastics as the demand for recycled materials increases.
A new, innovative use for recycled plastics may be energy production. Vilas Pol of Argonne National Laboratories has pioneered a process that disposes of plastic waste while producing energy and useful byproducts. It doesn't matter what type of plastics are used in this process, they are all just thrown in together. Plastics are heated at high temperature to produce spheres of pure carbon. These spheres conduct heat and electricity and could be a useful product with a multitude of applications. As the plastic is broken down into its basic elements, hydrogen gas is released. This gas can be captured and used as hydrogen fuel (Marshall). Innovative scientists come up with other possible solutions and uses for our excess of plastics every day. Necessity is the mother of invention, and it is becoming increasingly necessary for us to find alternative uses for our waste products.
As our global economy expands, there is an increasing need for materials packaging, containers, and synthetic materials. Luckily, the same science that brought us plastics is being applied to biodegradable alternatives. A new industry has sprung up around producing sustainable alternatives to plastic. Many of these products have become commercially available due to their ability to use existing plastic production equipment. They are produced using similar addition and condensation polymerization reactions using renewable sources such as corn starch, glucose and cellulose to form biodegradable polyesters.
Perhaps we've found a better use for corn than high fructose corn syrup. Plastic made from the fermentation of corn starch, called PLA (polylactic acid) is a strong, biodegradable thermoplastic. It can be used in the same application as PET for liquid bottles and food storage. PHB (poly-3-hydroxybutyrate) is produced by bacteria in the consumption of glucose. South America is taking advantage of their natural resources in sugar production and is producing PHB on an industrial scale (Bioplastics). These biopolymers appear very similar to petroleum based polymers and share many of the same characteristics. They can be used for insulation, packaging, food storage, heat resistance, and flexibility, all from a renewable biomass source. The major benefit of these products is that they are not made of petroleum products, and they can be disposed of through composting, leaving no discernible residue.
“All things in moderation” is not a bad motto to live by. We live in a world of ever-growing population and diminishing resources. In our effort to avoid scarcity, it became necessary throughout our recent history to find cost effective replacements for natural materials. We no longer use tortoise shell hair combs, or shoes with rubber soles from the gum of an Indian rubber tree. Plastics have made our lives safer, more efficient, and more comfortable. Facing growing problems from overflowing landfills, environmental concerns, and health risks, scientists are looking for new solutions and innovations for the plastics industry. Nanotechnology? Bioplastics? Flexible laptops with active matrix screens made possible by single layer plastic semiconductors?... Plastics. Yes, Mr. McGuire, we are still listening.
Works Cited
“Adverse Health Effects of Plastics”, ecologycenter.org, Ecology Center, 2001. http://www.ecologycenter.org/factsheets/plastichealtheffects.html
“The Benefits of Plastic”, plasticsindustry.com, Plastics Industry, 2010. http://www.plasticsindustry.com/plastics-benefits.asp
“Bioplastics”, en.wikipedia.org, WikiMedia Foundation, Inc., November 22, 2010. http://en.wikipedia.org/wiki/Bioplastic
Burcher, John, Ph.D., “Since You Asked – Bisphenol A (BPA)”, niehs.nih.gov, National Institute of Environmental Health Sciences – National Institute of Health, November 26, 2007. http://www.niehs.nih.gov/news/media/questions/sya-bpa.cfm
Freudenrich, Craig, Ph.D., “How Plastics Work”, science.howstuffworks.com, Discovery Company, 2007. http://science.howstuffworks.com/plastic3.htm
“The Future of Plastics and Nanotechnology”, plasticsindustry.com, Plastics Industry, 2010. http://www.plasticsindustry.com/plastics-and-nanotechnology.asp
Goebel, Greg, “Plastic”, en.wikipedia.org, March 2007, WikiMedia Foundation, Inc., November 19, 2010. http://en.wikipedia.org/wiki/Plastic
“The History of Plastic”, americanchemistry.com, American Chemistry Council, Inc., 2005-2010. http://www.americanchemistry.com/s_plastics/doc.asp?cid=1102&did=4665
“History of Polymers and Plastics for Teachers”, americanchemistry.com, American Chemistry Council, Inc., 2010. http://www.americanchemistry.com/s_plastics/hands_on_plastics/intro_to_plastics/teachers.html
Killinger, Jennifer, “Plastics Recycling in the United States”, December 17, 2009, americanchemistry.com, American Chemistry Council, Inc., 2005-2010. http://www.americanchemistry.com/s_plastics/sec_content.asp?CID=1102&DID=8811
Mackiewicz, Julia, “The Hazards of Plastics”, plasticfreebottles.com, 2007-2010. http://www.plasticfreebottles.com/pdf/HazardsPlastics.pdf
Marshall, Jessica, “Plastic Bags into Power”, June 25, 2010, news.discovery.com, Discovery Communications, LLC., 2010. http://news.discovery.com/earth/plastic-bags-power-recycling.html
Perkins, Jeremy, “The Story of Plastic: Discovery, Invention, and Practical Use”, History of Plastic: Facts, Stats, and Recycling Information, April 13, 2010. http://www.suite101.com/content/history-of-plastic-discovery-invention-and-practical-use-a221443
“Plastics in Daily Life”, totalpetrochemicals.com, Total Petrol Chemicals, Inc., 2010. http://www.totalpetrochemicals.com/EN/aboutus/presentation_activities/Pages/Plasticsindailylife.aspx
“Recycling Statistics and Facts”, all-recycling-facts.com, 2009. http://www.all-recycling-facts.com/recycling-statistics.html
“Recycling Symbols (US)”, earthodyssey.com, Earth Odyssey, LLC., 2000-2010. http://www.earthodyssey.com/symbols.html
