This was created to lend a better understanding concerning how plastics are produced, the different kinds of plastic as well as their numerous properties and applications.
A plastic is a type of synthetic or man-made polymer; similar often to natural resins located in trees as well as other plants. Webster’s Dictionary defines polymers as: any of various complex organic compounds made by polymerization, effective at being molded, extruded, cast into various shapes and films, or drawn into filaments and after that used as textile fibers.
Just A Little HistoryThe past of manufactured plastics goes back greater than a century; however, in comparison with other materials, plastics are relatively modern. Their usage during the last century has enabled society to produce huge technological advances. Although plastics are looked at as an advanced invention, there have invariably been “natural polymers” such as amber, tortoise shells and animal horns. These materials behaved very much like today’s manufactured plastics and were often used the same as the way manufactured plastics are presently applied. As an example, prior to the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes utilized to replace glass.
Alexander Parkes unveiled the first man-made plastic at the 1862 Great International Exhibition inside london. This material-which was dubbed Parkesine, now called celluloid-was an organic material based on cellulose that after heated might be molded but retained its shape when cooled. Parkes claimed this new material could do just about anything that rubber was effective at, yet on the cheap. He had discovered a material that could be transparent as well as carved into 1000s of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to generate a synthetic varnish, came across the formula for any new synthetic polymer caused by coal tar. He subsequently named the latest substance “Bakelite.” Bakelite, once formed, could not be melted. Because of its properties as being an electrical insulator, Bakelite was adopted in the production of high-tech objects including cameras and telephones. It was actually also found in the creation of ashtrays and as a substitute for jade, marble and amber. By 1909, Baekland had coined “plastics” as the term to clarify this completely new class of materials.
The first patent for pvc pellet, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane have also been discovered during this time.
Plastics did not really take off until following the First World War, if you use petroleum, a substance simpler to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal in the hardship times during World War’s I & II. After World War II, newer plastics, such as polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. More would follow and through the 1960s, plastics were within everyone’s reach because of their inexpensive cost. Plastics had thus come to be considered ‘common’-an expression of the consumer society.
Since the 1970s, we have witnessed the advent of ‘high-tech’ plastics employed in demanding fields such as health and technology. New types and kinds of plastics with new or improved performance characteristics continue being developed.
From daily tasks to our most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs at all levels. Plastics are employed such an array of applications since they are uniquely able to offering many different properties that provide consumer benefits unsurpassed by many other materials. Also, they are unique in this their properties can be customized for each and every individual end use application.
Oil and gas are the major raw materials employed to manufacture plastics. The plastics production process often begins by treating parts of oil or natural gas in a “cracking process.” This method leads to the conversion of these components into hydrocarbon monomers for example ethylene and propylene. Further processing leads to a wider array of monomers for example styrene, upvc compound, ethylene glycol, terephthalic acid and more. These monomers are then chemically bonded into chains called polymers. The numerous mixtures of monomers yield plastics with a wide array of properties and characteristics.
PlasticsMany common plastics are made of hydrocarbon monomers. These plastics are created by linking many monomers together into long chains produce a polymer backbone. Polyethylene, polypropylene and polystyrene are the most common types of these. Below is really a diagram of polyethylene, the easiest plastic structure.
However the basic makeup of countless plastics is carbon and hydrogen, other elements can even be involved. Oxygen, chlorine, fluorine and nitrogen may also be based 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 up into two distinct groups: thermoplastics and thermosets. Virtually all plastics are thermoplastic, meaning 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. One other group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating may cause the information to decompose as an alternative to melt. Bakelite, poly phenol formaldehyde, is a thermoset.
Each plastic has very distinct characteristics, but the majority plastics possess the following general attributes.
Plastics are often very proof against chemicals. Consider all the cleaning fluids in your home which can be packaged in plastic. The warning labels describing what happens if the chemical makes exposure to skin or eyes or perhaps is ingested, emphasizes the chemical resistance of the materials. While solvents easily dissolve some plastics, other plastics provide safe, non-breakable packages for aggressive solvents.
Plastics could be both thermal and electrical insulators. A walk via your house will reinforce this idea. Consider all the electrical appliances, cords, outlets and wiring which are made or covered with 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 a great many skiers wear is made of polypropylene and also the fiberfill in lots of winter jackets is acrylic or polyester.
Generally, plastics are incredibly lightweight with varying levels of strength. Consider all the different applications, from toys towards the frame structure of space stations, or from delicate nylon fiber in pantyhose to Kevlar®, which is often used in bulletproof vests. Some polymers float in water and some sink. But, in comparison to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics may be processed in a variety of strategies to produce thin fibers or very intricate parts. Plastics might be molded into bottles or components of cars, such as dashboards and fenders. Some pvcppellet stretch and therefore are very flexible. Other plastics, such as polyethylene, polystyrene (Styrofoam™) and polyurethane, may be foamed. Plastics may be molded into drums or even be mixed with solvents in becoming adhesives or paints. Elastomers plus some plastics stretch and are very flexible.
Polymers are materials with a seemingly limitless variety of characteristics and colors. Polymers have many inherent properties that may be further enhanced by an array of additives to broaden their uses and applications. Polymers can be done to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers also can make possible products that do not readily range from natural world, including clear sheets, foamed insulation board, and versatile films. Plastics can be molded or formed to create many kinds of merchandise with application in several major markets.
Polymers are often created from petroleum, yet not always. Many polymers are constructed with repeat units derived from natural gas or coal or oil. But foundation repeat units can sometimes be created from renewable materials for example polylactic acid from corn or cellulosics from cotton linters. Some plastics have always been made out of renewable materials such as cellulose acetate used for screwdriver handles and gift ribbon. If the building blocks can be produced more economically from renewable materials than from fossil fuels, either old plastics find new raw materials or new plastics are introduced.
Many plastics are combined with additives as they are processed into finished products. The additives are incorporated into plastics to change and boost their basic mechanical, physical, or chemical properties. Additives are employed to protect plastics from your degrading outcomes of light, heat, or bacteria; to improve such plastic properties, for example melt flow; to supply color; to deliver foamed structure; to offer flame retardancy; as well as provide special characteristics including improved surface appearance or reduced tack/friction.
Plasticizers are materials incorporated into certain plastics to boost flexibility and workability. Plasticizers can be found in many plastic film wraps as well as in flexible plastic tubing, both of which are typically utilized in food packaging or processing. All plastics used in food contact, like the additives and plasticizers, are regulated from the U.S. Food and Drug Administration (FDA) to ensure that these materials are secure.
Processing MethodsThere are many different processing methods utilized to make plastic products. Below are the 4 main methods where plastics are processed to produce the merchandise that consumers use, for example plastic film, bottles, bags and other containers.
Extrusion-Plastic pellets or granules are first loaded right into a hopper, then fed into an extruder, and that is a long heated chamber, in which it is moved by the act of a continuously revolving screw. The plastic is melted by a mix of heat through the mechanical work done and also by the recent sidewall metal. At the conclusion of the extruder, the molten plastic is forced out using a small opening or die to shape the finished product. Since the plastic product extrudes from your 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 the hopper right into a heating chamber. An extrusion screw pushes the plastic with the heating chamber, where material is softened right into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. Following this chamber, the resin is forced at high-pressure into a cooled, closed mold. Once the plastic cools to a solid state, the mold opens along with the finished part is ejected. This technique is used to make products such as butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is a process used in conjunction with extrusion or injection molding. In one form, extrusion blow molding, the die forms a continuous semi-molten tube of thermoplastic material. A chilled mold is clamped across the tube and compressed air will be blown in the tube to conform the tube to the interior from the mold and to solidify the stretched tube. Overall, the aim is to produce a uniform melt, form it in to a tube with all the desired cross section and blow it in the exact model of the product. This process is used to produce hollow plastic products as well as its principal advantage is being able to produce hollow shapes and never have to join 2 or more separately injection molded parts. This method is commonly used to help make items such as commercial drums and milk bottles. Another blow molding method is to injection mold an intermediate shape termed as a preform and then to heat the preform and blow the high temperature-softened plastic in the final shape inside a chilled mold. This is the process to help make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes closed mold placed on a unit capable of rotation on two axes simultaneously. Plastic granules are positioned in the mold, that is then heated inside an oven to melt the plastic Rotation around both axes distributes the molten plastic in to a uniform coating on the inside of the mold up until the part is defined by cooling. This procedure is utilized to create hollow products, for example large toys or kayaks.
Durables vs. Non-DurablesAll kinds of plastic products are classified in the plastic industry to be either a durable or non-durable plastic good. These classifications are used to refer to a product’s expected life.
Products having a useful lifetime of three years or maybe more are termed as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products by using a useful lifetime of lower than 36 months are typically known 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 apparent, tough and contains good gas and moisture barrier properties rendering it perfect for carbonated beverage applications as well as other food containers. The fact that it provides high use temperature allows that it is employed in applications such as heatable pre-prepared food trays. Its heat resistance and microwave transparency help it become a perfect heatable film. It also finds applications in 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) can be used for most packaging applications as it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all sorts of polyethylene, has limitations to those food packaging applications which do not require an oxygen or CO2 barrier. In film form, HDPE is commonly used in snack food packages and cereal box liners; in blow-molded bottle form, for milk and non-carbonated beverage bottles; and also in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it really is used for packaging many household along with industrial chemicals like 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 can be broadly divided into rigid and flexible materials. Rigid applications are concentrated in construction markets, which include pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings may be associated with its effectiveness against most chemicals, imperviousness to attack by bacteria or micro-organisms, corrosion resistance and strength. Flexible vinyl is commonly used 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 utilized in film applications due to the toughness, flexibility and transparency. LDPE carries a low melting point which makes it popular to be used in applications where heat sealing is necessary. Typically, LDPE can be used to produce flexible films including those used for dry cleaned garment bags and produce bags. LDPE can also be used to manufacture some flexible lids and bottles, which is widely used in wire and cable applications for its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and is frequently used in packaging. It has a high melting point, so that it is well suited for hot fill liquids. Polypropylene is located in everything from flexible and rigid packaging to fibers for fabrics and carpets and large molded parts for automotive and consumer products. Like other plastics, polypropylene has excellent resistance to water as well as salt and acid solutions that happen to be 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 which can be rigid or foamed. General purpose polystyrene is apparent, hard and brittle. Its clarity allows that it is used when transparency is very important, as with medical and food packaging, in laboratory ware, and then in certain electronic uses. Expandable Polystyrene (EPS) is commonly extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers including egg crates. EPS is additionally directly formed into cups and tubs for dry foods including dehydrated soups. Both foamed sheet and molded tubs are utilized extensively in take-out restaurants for his or her lightweight, stiffness and ideal thermal insulation.
If you are aware about it or perhaps not, plastics play an important part in your life. Plastics’ versatility allow them to be utilized in anything from car parts to doll parts, from soft drink bottles to the refrigerators they may be saved in. From the car you drive to function in the television you watch at home, plastics help make your life easier and much better. Now how will it be that plastics have become so commonly used? How did plastics become the material of choice for countless varied applications?
The basic answer is that plastics provides the items consumers want and require at economical costs. Plastics have the unique ability to be manufactured to meet very specific functional needs for consumers. So maybe there’s another question that’s relevant: What do I want? No matter how you answer this inquiry, plastics can probably suit your needs.
If your product is constructed of plastic, there’s grounds. And chances are the main reason has everything with regards to helping you to, the consumer, get what you wish: Health. Safety. Performance. and Value. Plastics Have The Ability.
Just take into account the changes we’ve noticed in the supermarket lately: plastic wrap helps keep meat fresh while protecting it in the poking and prodding fingers of your fellow shoppers; plastic bottles mean you can actually lift an economy-size bottle of juice and really should you accidentally drop that bottle, it can be shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also aid you in getting maximum value from some of the big-ticket stuff you buy. Plastics help make portable phones and computers that really are portable. They assist major appliances-like refrigerators or dishwashers-resist corrosion, stay longer and operate more effectively. Plastic car fenders and body panels resist dings, so that you can cruise the grocery store car park with full confidence.
Modern packaging-including heat-sealed plastic pouches and wraps-assists in keeping food fresh and free of contamination. It means the time that went into producing that food aren’t wasted. It’s the exact same thing when you obtain the food home: plastic wraps and resealable containers maintain your leftovers protected-much to the chagrin of kids everywhere. In reality, 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. As an example, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of any beverage like juice, soda or water. You’d need 3 pounds of aluminum to create home the equivalent amount of product, 8 pounds of steel or over 40 pounds of glass. In addition plastic bags require less total energy to make than paper bags, they conserve fuel in shipping. It will require seven trucks to hold the same amount of paper bags as suits one truckload of plastic bags. Plastics make packaging more effective, which ultimately conserves resources.
LightweightingPlastics engineers will almost always be working to do even more with less material. Since 1977, the two-liter plastic soft drink bottle has gone from weighing 68 grams just to 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 a similar reduction, weighing 30 percent below exactly what it did 20 years ago.
Doing more with less helps conserve resources in one other way. It may help save energy. Actually, plastics can enjoy a significant role in energy conservation. Just look at the decision you’re inspired to make on the food store checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less freshwater than does paper bag manufacture. In addition plastic bags require less total production energy to generate than paper bags, they conserve fuel in shipping. It requires seven trucks to transport a similar variety of paper bags as suits one truckload of plastic bags.
Plastics also assistance to conserve energy at your residence. Vinyl siding and windows help cut energy consumption and reduce air conditioning bills. Furthermore, the Usa Department of Energy estimates which use of plastic foam insulation in homes and buildings each year could save over 60 million barrels of oil over other sorts of insulation.
A similar principles apply in appliances like refrigerators and ac units. Plastic parts and insulation have helped to further improve their energy efficiency by 30 to one half ever since the early 1970s. Again, this energy savings helps reduce your heating and air conditioning bills. And appliances run more quietly than earlier designs that used other materials.
Recycling of post-consumer plastics packaging began in early 1980s on account of state level bottle deposit programs, which produced a regular flow of returned PETE bottles. With adding HDPE milk jug recycling within the late 1980s, plastics recycling has expanded steadily but relative to competing packaging materials.
Roughly 60 % in the Usa population-about 148 million people-have accessibility to a plastics recycling program. The 2 common types of collection are: curbside collection-where consumers place designated plastics within a special bin to become 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 type of plastic resin; usually both PETE and HDPE. Once collected, the plastics are delivered 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 reduce shipping costs to reclaimers.
Reclamation is the next step where plastics are chopped into flakes, washed to get rid of contaminants and sold to finish users to manufacture new products including bottles, containers, clothing, carpet, clear pvc granule, etc. The quantity of companies handling and reclaiming post-consumer plastics today has finished 5 times higher than in 1986, growing from 310 companies to 1,677 in 1999. The number of end uses for recycled plastics is growing. The government and state government and also many major corporations now support market growth through purchasing preference policies.
At the beginning of the 1990s, concern over the perceived decrease in landfill capacity spurred efforts by legislators to mandate the use of recycled materials. Mandates, as a way of expanding markets, could be troubling. Mandates may neglect to take health, safety and gratification attributes under consideration. Mandates distort the economic decisions and can lead to sub optimal financial results. Moreover, they are not able to acknowledge the lifespan cycle advantages of options to the planet, like the efficient use of energy and natural resources.
Pyrolysis involves heating plastics within the absence or near absence of oxygen to get rid of on the long polymer chains into small molecules. Under mild conditions polyolefins can yield a petroleum-like oil. Special conditions can yield monomers including ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and deadly carbon monoxide are known as synthesis gas, or syngas). Contrary to pyrolysis, combustion is undoubtedly an oxidative method that generates heat, fractional co2, and water.
Chemical recycling is actually a special case where condensation polymers including PET or nylon are chemically reacted to produce starting materials.
Source ReductionSource reduction is gaining more attention as an important resource conservation and solid waste management option. Source reduction, typically referred to as “waste prevention” is defined as “activities to reduce the amount of material in products and packaging before that material enters the municipal solid waste management system.”