This was designed to lend a greater understanding concerning how plastics are made, the different kinds of plastic and their numerous properties and applications.
A plastic is a form of synthetic or man-made polymer; similar in lots of ways to natural resins present in trees as well as other plants. Webster’s Dictionary defines polymers as: any of various complex organic compounds created by polymerization, competent at being molded, extruded, cast into various shapes and films, or drawn into filaments and then used as textile fibers.
A Little Bit HistoryThe history of manufactured plastics dates back a lot more than a century; however, when compared to other materials, plastics are relatively modern. Their usage within the last century has enabled society to make huge technological advances. Although plastics are thought of as an advanced invention, there have always been “natural polymers” like amber, tortoise shells and animal horns. These materials behaved like today’s manufactured plastics and were often used similar to the way manufactured plastics are currently applied. For example, just before the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes used to replace glass.
Alexander Parkes unveiled the first man-made plastic with the 1862 Great International Exhibition in London. This product-which was dubbed Parkesine, now called celluloid-was an organic material based on cellulose that once heated might be molded but retained its shape when cooled. Parkes claimed that it new material could do just about anything that rubber was able to, yet on the cheap. He had discovered a material that might be transparent and also carved into thousands of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to produce a synthetic varnish, stumbled upon the formula for any new synthetic polymer caused by coal tar. He subsequently named the new substance “Bakelite.” Bakelite, once formed, could not really melted. Because of its properties as an electrical insulator, Bakelite was applied in the creation of high-tech objects including cameras and telephones. It was actually also found in the creation of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” since the term to explain this completely new category of materials.
The very first patent for pvc compound, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane have also been discovered during this time.
Plastics failed to really take off until once the First World War, if you use petroleum, a substance easier to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal throughout the hardship times of World War’s I & II. After World War 2, newer plastics, such as polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. Many more would follow and by the 1960s, plastics were within everyone’s reach because of their inexpensive cost. Plastics had thus come to be considered ‘common’-a symbol from the consumer society.
Since the 1970s, we have witnessed the advent of ‘high-tech’ plastics used in demanding fields including health insurance and technology. New types and forms of plastics with new or improved performance characteristics continue to be developed.
From daily tasks to the most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs by any means levels. Plastics are being used such a wide range of applications because they are uniquely competent at offering numerous properties that supply consumer benefits unsurpassed by many other materials. Also, they are unique for the reason that their properties can be customized for each individual end use application.
Oil and natural gas are definitely the major raw materials used to manufacture plastics. The plastics production process often begins by treating components of oil or gas inside a “cracking process.” This process contributes to the conversion of such components into hydrocarbon monomers such as ethylene and propylene. Further processing leads to a wider array of monomers for example styrene, upvc compound, ethylene glycol, terephthalic acid and others. These monomers are then chemically bonded into chains called polymers. The many combinations of monomers yield plastics with a variety of properties and characteristics.
PlasticsMany common plastics are manufactured from hydrocarbon monomers. These plastics are made by linking many monomers together into long chains to make a polymer backbone. Polyethylene, polypropylene and polystyrene are the most prevalent types of these. Below is a diagram of polyethylene, the most basic plastic structure.
Although the basic makeup of many plastics is carbon and hydrogen, other elements may also be involved. Oxygen, chlorine, fluorine and nitrogen are also in the molecular makeup of numerous plastics. Polyvinyl chloride (PVC) contains chlorine. Nylon contains nitrogen. Teflon contains fluorine. Polyester and polycarbonates contain oxygen.
Characteristics of Plastics Plastics are split into two distinct groups: thermoplastics and thermosets. Nearly all plastics are thermoplastic, which means that after the plastic is actually created it can be heated and reformed repeatedly. Celluloid can be a thermoplastic. This property enables easy processing and facilitates recycling. The other group, the thermosets, cannot be remelted. Once these plastics are formed, reheating can cause the fabric to decompose instead of melt. Bakelite, poly phenol formaldehyde, is actually a thermoset.
Each plastic has very distinct characteristics, but the majority plastics possess the following general attributes.
Plastics are often very immune to chemicals. Consider all the cleaning fluids in your home that are packaged in plastic. The warning labels describing what happens if the chemical enters into experience of skin or eyes or maybe ingested, emphasizes the chemical resistance of those materials. While solvents easily dissolve some plastics, other plastics provide safe, non-breakable packages for aggressive solvents.
Plastics can be both thermal and electrical insulators. A walk via your house will reinforce this concept. Consider all of the electrical appliances, cords, outlets and wiring that happen to be made or engrossed in plastics. Thermal resistance is evident with the cooking with plastic pot and pan handles, coffee pot handles, the foam core of refrigerators and freezers, insulated cups, coolers and microwave cookware. The thermal underwear that lots of skiers wear is constructed of polypropylene along with the fiberfill in several winter jackets is acrylic or polyester.
Generally, plastics are really light in weight with varying degrees of strength. Consider the plethora of applications, from toys for the frame structure of space stations, or from delicate nylon fiber in pantyhose to Kevlar®, which is used in bulletproof vests. Some polymers float in water while some sink. But, in comparison to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics might be processed in several ways to produce thin fibers or very intricate parts. Plastics can be molded into bottles or components of cars, like dashboards and fenders. Some pvcppellet stretch and they are very flexible. Other plastics, like polyethylene, polystyrene (Styrofoam™) and polyurethane, can be foamed. Plastics could be molded into drums or even be mixed with solvents to get adhesives or paints. Elastomers and some plastics stretch and they are very flexible.
Polymers are materials by using a seemingly limitless range of characteristics and colors. Polymers have lots of inherent properties which can be further enhanced by an array of additives to broaden their uses and applications. Polymers can be created to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers can also make possible products that do not readily range from natural world, including clear sheets, foamed insulation board, and versatile films. Plastics could be molded or formed to generate many kinds of items with application in numerous major markets.
Polymers tend to be manufactured from petroleum, although not always. Many polymers are constructed with repeat units derived from natural gas or coal or crude oil. But building block repeat units can occasionally be made from renewable materials like polylactic acid from corn or cellulosics from cotton linters. Some plastics have always been produced from renewable materials for example cellulose acetate used for screwdriver handles and gift ribbon. Once the building blocks can be done more economically from renewable materials than from standard fuels, either old plastics find new raw materials or new plastics are introduced.
Many plastics are combined with additives because they are processed into finished products. The additives are included in plastics to alter and enhance their basic mechanical, physical, or chemical properties. Additives are utilized to protect plastics through the degrading negative effects of light, heat, or bacteria; to change such plastic properties, including melt flow; to offer color; to supply foamed structure; to supply flame retardancy; and to provide special characteristics like improved surface appearance or reduced tack/friction.
Plasticizers are materials integrated into certain plastics to improve flexibility and workability. Plasticizers are located in several plastic film wraps as well as in flexible plastic tubing, both of which are commonly employed in food packaging or processing. All plastics used in food contact, such as the additives and plasticizers, are regulated through the U.S. Food and Drug Administration (FDA) to make certain that these materials are safe.
Processing MethodsThere are several different processing methods employed to make plastic products. Listed below are the four main methods where plastics are processed to produce the items that consumers use, for example plastic film, bottles, bags along with other containers.
Extrusion-Plastic pellets or granules are first loaded in a hopper, then fed into an extruder, which is a long heated chamber, by which it is moved by the act of a continuously revolving screw. The plastic is melted by a variety of heat from your mechanical work done and by the sidewall metal. Following the extruder, the molten plastic needs out by way of a small opening or die to shape the finished product. As the plastic product extrudes in the die, it is actually cooled by air or water. Plastic films and bags are manufactured by extrusion processing.
Injection molding-Injection molding, plastic pellets or granules are fed from your hopper into a heating chamber. An extrusion screw pushes the plastic from the heating chamber, where the material is softened in a fluid state. Again, mechanical work and hot sidewalls melt the plastic. After this chamber, the resin is forced at high-pressure in to a cooled, closed mold. After the plastic cools to a solid state, the mold opens as well as the finished part is ejected. This method is used to produce products like butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is a process used in conjunction with extrusion or injection molding. In just one form, extrusion blow molding, the die forms a continuous semi-molten tube of thermoplastic material. A chilled mold is clamped throughout the tube and compressed air is then blown into the tube to conform the tube on the interior in the mold as well as to solidify the stretched tube. Overall, the objective is to make a uniform melt, form it in a tube using the desired cross section and blow it to the exact model of the item. This method can be used to produce hollow plastic products as well as its principal advantage is its capability to produce hollow shapes and never have to join two or more separately injection molded parts. This procedure can be used to create items such as commercial drums and milk bottles. Another blow molding technique is to injection mold an intermediate shape known as a preform after which to heat the preform and blow the temperature-softened plastic in to the final shape in a chilled mold. This is basically the process to make carbonated soft drink bottles.
Rotational Molding-Rotational molding consists of a closed mold placed on a machine competent at rotation on two axes simultaneously. Plastic granules are positioned from the mold, which can be then heated in a oven to melt the plastic Rotation around both axes distributes the molten plastic into a uniform coating on the inside of the mold till the part is defined by cooling. This technique is utilized to make hollow products, for instance large toys or kayaks.
Durables vs. Non-DurablesAll varieties of plastic merchandise is classified in the plastic industry to be either a durable or non-durable plastic good. These classifications are utilized to talk about a product’s expected life.
Products using a useful life of three years or maybe more are termed as durables. They include appliances, furniture, electronic products, automobiles, and building and construction materials.
Products using a useful lifetime of below 36 months are typically termed as non-durables. Common applications include packaging, trash bags, cups, eating utensils, sporting and recreational equipment, toys, medical devices and disposable diapers.
Polyethylene Terephthalate (PET or PETE) is obvious, tough and it has good gas and moisture barrier properties so that it is ideal for carbonated beverage applications and other food containers. The point that it has high use temperature allows so that it is utilized in applications for example heatable pre-prepared food trays. Its heat resistance and microwave transparency ensure it is an excellent heatable film. Additionally, it finds applications such diverse end uses as fibers for clothing and carpets, bottles, food containers, strapping, and engineering plastics for precision-molded parts.
High Density Polyethylene (HDPE) is utilized for several packaging applications since it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like a variety of polyethylene, has limitations to those food packaging applications that do not require an oxygen or CO2 barrier. In film form, HDPE is used in snack food packages and cereal box liners; in blow-molded bottle form, for milk and non-carbonated beverage bottles; and then in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it is useful for packaging many household in addition to industrial chemicals for example detergents, bleach and acids. General uses of HDPE include injection-molded beverage cases, bread trays along with films for grocery sacks and bottles for beverages and household chemicals.
Polyvinyl Chloride (PVC) has excellent transparency, chemical resistance, long lasting stability, good weatherability and stable electrical properties. Vinyl products may be broadly separated into rigid and versatile materials. Rigid applications are concentrated in construction markets, which includes pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings could be caused by its potential to deal with most chemicals, imperviousness to attack by bacteria or micro-organisms, corrosion resistance and strength. Flexible vinyl is utilized in wire and cable sheathing, insulation, film and sheet, flexible floor coverings, synthetic leather products, coatings, blood bags, and medical tubing.
Low Density Polyethylene (LDPE) is predominantly employed in film applications because of its toughness, flexibility and transparency. LDPE includes a low melting point so that it is popular to use in applications where heat sealing is necessary. Typically, LDPE is utilized to manufacture flexible films including those used for dry cleaned garment bags and provide bags. LDPE can also be used to manufacture some flexible lids and bottles, and is particularly popular in wire and cable applications because of its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and it is popular in packaging. It has a high melting point, so that it is suitable for hot fill liquids. Polypropylene can be found in everything from flexible and rigid packaging to fibers for fabrics and carpets and huge molded parts for automotive and consumer products. Like other plastics, polypropylene has excellent resistance to water as well as to salt and acid solutions which are destructive to metals. Typical applications include ketchup bottles, yogurt containers, medicine bottles, pancake syrup bottles and automobile battery casings.
Polystyrene (PS) is actually a versatile plastic that may be rigid or foamed. General purpose polystyrene is apparent, hard and brittle. Its clarity allows so that it is used when transparency is very important, as in medical and food packaging, in laboratory ware, and then in certain electronic uses. Expandable Polystyrene (EPS) is normally extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers including egg crates. EPS is likewise directly formed into cups and tubs for dry foods for example dehydrated soups. Both foamed sheet and molded tubs are used extensively in take-out restaurants for his or her lightweight, stiffness and excellent thermal insulation.
If you are aware about it or not, plastics play a crucial part in your lifetime. Plastics’ versatility permit them to be utilized in anything from car parts to doll parts, from soft drink bottles for the refrigerators they may be stored in. From the car you drive to function into the television you watch in your own home, plastics make your life easier and. Now how could it be that plastics are becoming so traditionally used? How did plastics become the material preferred by numerous varied applications?
The easy response is that plastics can provide the points consumers want and require at economical costs. Plastics hold the unique ability to be manufactured to satisfy very specific functional needs for consumers. So maybe there’s another question that’s relevant: Exactly what do I want? Regardless how you answer this question, plastics can probably satisfy your needs.
When a product consists of plastic, there’s grounds. And chances are the reason why has everything to do with helping you to, the consumer, get what you need: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just consider the changes we’ve noticed in the food store lately: plastic wrap helps keep meat fresh while protecting it through the poking and prodding fingers of your own fellow shoppers; plastic containers mean it is possible to lift an economy-size bottle of juice and should you accidentally drop that bottle, it can be shatter-resistant. In each case, plastics make your life easier, healthier and safer.
Plastics also help you to get maximum value from a number of the big-ticket items you buy. Plastics make portable phones and computers that basically are portable. They help major appliances-like refrigerators or dishwashers-resist corrosion, last longer and operate more proficiently. Plastic car fenders and the body panels resist dings, in order to cruise the supermarket parking lot with certainty.
Modern packaging-for example heat-sealed plastic pouches and wraps-helps keep food fresh and without any contamination. That means the time that went into producing that food aren’t wasted. It’s the exact same thing once you obtain the food home: plastic wraps and resealable containers maintain your leftovers protected-much on the chagrin of kids everywhere. The truth is, packaging experts have estimated that each pound of plastic packaging is able to reduce food waste by approximately 1.7 pounds.
Plastics can also help you bring home more product with less packaging. For instance, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of the beverage such as juice, soda or water. You’d need 3 pounds of aluminum to give home the equivalent amount of product, 8 pounds of steel or higher 40 pounds of glass. In addition plastic bags require less total energy to make than paper bags, they conserve fuel in shipping. It will take seven trucks to carry a similar amount of paper bags as suits one truckload of plastic bags. Plastics make packaging more effective, which ultimately conserves resources.
LightweightingPlastics engineers will always be trying to do much more with less material. Since 1977, the two-liter plastic soft drink bottle has gone from weighing 68 grams to simply 47 grams today, representing a 31 percent reduction per bottle. That saved greater than 180 million pounds of packaging in 2006 for just 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone an identical reduction, weighing 30 percent less than exactly what it did 20 years ago.
Doing more with less helps conserve resources in a different way. It can help save energy. Actually, plastics can enjoy a significant role in energy conservation. Just check out the decision you’re inspired to make at the food store checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less freshwater than does paper bag manufacture. Furthermore plastic bags require less total production energy to create than paper bags, they conserve fuel in shipping. It will require seven trucks to carry exactly the same amount of paper bags as fits in one truckload of plastic bags.
Plastics also assist to conserve energy in your home. Vinyl siding and windows help cut energy consumption and minimize heating and cooling bills. Furthermore, the United states Department of Energy estimates that use of plastic foam insulation in homes and buildings every year could save over 60 million barrels of oil over other sorts of insulation.
The identical principles apply in appliances like refrigerators and air conditioners. Plastic parts and insulation have helped to further improve their energy efficiency by 30 to one half since the early 1970s. Again, this energy savings helps in reducing your heating and air conditioning bills. And appliances run more quietly than earlier designs that used many other materials.
Recycling of post-consumer plastics packaging began in the early 1980s because of state level bottle deposit programs, which produced a consistent supply of returned PETE bottles. With incorporating HDPE milk jug recycling from the late 1980s, plastics recycling has exploded steadily but relative to competing packaging materials.
Roughly 60 percent of your United states population-about 148 million people-have accessibility to a plastics recycling program. Both common kinds of collection are: curbside collection-where consumers place designated plastics in a special bin being gathered with a public or private hauling company (approximately 8,550 communities participate in curbside recycling) and drop-off centers-where consumers take their recyclables to your centrally located facility (12,000). Most curbside programs collect a couple of sort of plastic resin; usually both PETE and HDPE. Once collected, the plastics are transported to a material recovery facility (MRF) or handler for sorting into single resin streams to enhance product value. The sorted plastics are then baled to minimize shipping costs to reclaimers.
Reclamation is the next thing where the plastics are chopped into flakes, washed to get rid of contaminants and sold to terminate users to produce new items for example bottles, containers, clothing, carpet, pvc compound, etc. The volume of companies handling and reclaiming post-consumer plastics today has ended 5 times higher than in 1986, growing from 310 companies to 1,677 in 1999. The amount of end uses for recycled plastics continues to grow. The federal and state government along with many major corporations now support market growth through purchasing preference policies.
Early in the 1990s, concern across the perceived reduction of landfill capacity spurred efforts by legislators to mandate the usage of recycled materials. Mandates, as a method of expanding markets, can be troubling. Mandates may forget to take health, safety and gratifaction attributes into account. Mandates distort the economic decisions and can lead to sub optimal financial results. Moreover, they are not able to acknowledge the lifespan cycle benefits of choices to environmental surroundings, for example the efficient consumption of energy and natural resources.
Pyrolysis involves heating plastics from the absence or near lack of oxygen to get rid of along the long polymer chains into small molecules. Under mild conditions polyolefins can yield a petroleum-like oil. Special conditions can yield monomers such as ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and carbon monoxide are classified as synthesis gas, or syngas). Unlike pyrolysis, combustion is definitely an oxidative process that generates heat, fractional co2, and water.
Chemical recycling is actually a special case where condensation polymers like PET or nylon are chemically reacted to create starting materials.
Source ReductionSource reduction is gaining more attention for an important resource conservation and solid waste management option. Source reduction, often called “waste prevention” is described as “activities to lessen the level of material in products and packaging before that material enters the municipal solid waste management system.”