This was created to lend a much better understanding concerning how plastics are produced, the different kinds of plastic and their numerous properties and applications.
A plastic is a type of synthetic or man-made polymer; similar often to natural resins located in trees and other plants. Webster’s Dictionary defines polymers as: any kind of various complex organic compounds made by polymerization, competent at being molded, extruded, cast into various shapes and films, or drawn into filaments and after that used as textile fibers.
A Little Bit HistoryThe reputation of manufactured plastics dates back more than a century; however, when compared with many other materials, plastics are relatively modern. Their usage in the last century has enabled society to help make huge technological advances. Although plastics are thought of as an advanced invention, there have been “natural polymers” like amber, tortoise shells and animal horns. These materials behaved similar to today’s manufactured plastics and were often used similar to the way manufactured plastics are applied. For example, just before the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes accustomed to replace glass.
Alexander Parkes unveiled the 1st man-made plastic on the 1862 Great International Exhibition in the uk. This material-that 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 this new material could do just about anything that rubber was competent at, yet at a lower price. He had discovered a material that might be transparent along with carved into 1000s of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to make a synthetic varnish, discovered the formula for a new synthetic polymer originating from coal tar. He subsequently named the new substance “Bakelite.” Bakelite, once formed, could stop being melted. Due to the properties for an electrical insulator, Bakelite was adopted in producing high-tech objects including cameras and telephones. It had been also employed in the creation of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” as being the term to explain this completely new group of materials.
The very first patent for pvc pellet, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane was discovered during this time.
Plastics failed to really take off until right after the First World War, by using petroleum, a substance simpler to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal during the hardship times of World War’s I & II. After World War II, newer plastics, including polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. Much 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 in the consumer society.
Considering that the 1970s, we have now witnessed the advent of ‘high-tech’ plastics utilized in demanding fields like health and technology. New types and sorts of plastics with new or improved performance characteristics continue to be developed.
From daily tasks to our own most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs in any way levels. Plastics are used in such a wide range of applications as they are uniquely able to offering a number of properties that provide consumer benefits unsurpassed by other materials. They are also unique for the reason that their properties could be customized for each individual end use application.
Oil and gas will be the major raw materials accustomed to manufacture plastics. The plastics production process often begins by treating aspects of oil or natural gas in the “cracking process.” This process contributes to the conversion of those components into hydrocarbon monomers including ethylene and propylene. Further processing leads to a wider array of monomers such as styrene, soft pvc granule, 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 wide range of properties and characteristics.
PlasticsMany common plastics are produced from hydrocarbon monomers. These plastics are created by linking many monomers together into long chains to form a polymer backbone. Polyethylene, polypropylene and polystyrene are the most frequent instances of these. Below is actually a diagram of polyethylene, the simplest plastic structure.
Although the basic makeup of countless plastics is carbon and hydrogen, other elements may also be involved. Oxygen, chlorine, fluorine and nitrogen are also 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. Nearly all plastics are thermoplastic, which means that after the plastic is formed it may be heated and reformed repeatedly. Celluloid is really a thermoplastic. This property enables easy processing and facilitates recycling. Another group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating will cause the content to decompose as an alternative to melt. Bakelite, poly phenol formaldehyde, is a thermoset.
Each plastic has very distinct characteristics, but most plastics hold the following general attributes.
Plastics can be quite resistant to chemicals. Consider all the cleaning fluids at home which are packaged in plastic. The warning labels describing what will happen if the chemical makes experience of skin or eyes or maybe 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 can be both thermal and electrical insulators. A walk via your house will reinforce this idea. Consider every one of the electrical appliances, cords, outlets and wiring that happen to be made or engrossed in plastics. Thermal resistance is evident in the kitchen area 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 many skiers wear consists of polypropylene along with the fiberfill in lots of winter jackets is acrylic or polyester.
Generally, plastics are really light-weight with varying degrees of strength. Consider the plethora of applications, from toys on the frame structure of space stations, or from delicate nylon fiber in pantyhose to Kevlar®, that is utilized in bulletproof vests. Some polymers float in water and some sink. But, when compared to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics might be processed in different approaches to produce thin fibers or very intricate parts. Plastics may be molded into bottles or parts of cars, like dashboards and fenders. Some pvcppellet stretch and are very flexible. Other plastics, including polyethylene, polystyrene (Styrofoam™) and polyurethane, could be foamed. Plastics can be molded into drums or perhaps be combined with solvents to become adhesives or paints. Elastomers and several plastics stretch and are very flexible.
Polymers are materials with a seemingly limitless array of characteristics and colors. Polymers have several inherent properties that could 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 may also make possible products that do not readily come from the natural world, including clear sheets, foamed insulation board, and versatile films. Plastics may be molded or formed to produce many kinds of merchandise with application in many major markets.
Polymers tend to be made from petroleum, although not always. Many polymers are constructed with repeat units produced by gas or coal or oil. But building block repeat units is often made from renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have been made out of renewable materials including cellulose acetate used for screwdriver handles and gift ribbon. As soon as the foundations can be created more economically from renewable materials than from standard fuels, either old plastics find new raw materials or new plastics are introduced.
Many plastics are blended with additives as they are processed into finished products. The additives are incorporated into plastics to change and increase their basic mechanical, physical, or chemical properties. Additives are widely used to protect plastics from your degrading negative effects of light, heat, or bacteria; to change such plastic properties, including melt flow; to supply color; to provide foamed structure; to supply flame retardancy; and to provide special characteristics for example improved surface appearance or reduced tack/friction.
Plasticizers are materials integrated into certain plastics to enhance flexibility and workability. Plasticizers are located in many plastic film wraps and in flexible plastic tubing, both of which are commonly found in food packaging or processing. All plastics utilized in food contact, including the additives and plasticizers, are regulated from the United states 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. Here are the four main methods by which plastics are processed to produce the merchandise that consumers use, like plastic film, bottles, bags and other containers.
Extrusion-Plastic pellets or granules are first loaded right into a hopper, then fed into an extruder, that is a long heated chamber, in which it can be moved by the act of a continuously revolving screw. The plastic is melted by a mix of heat in the mechanical work done and also by the recent sidewall metal. Following the extruder, the molten plastic is forced out using a small opening or die to shape the finished product. As being the plastic product extrudes from your die, it is cooled by air or water. Plastic films and bags are created by extrusion processing.
Injection molding-Injection molding, plastic pellets or granules are fed from your hopper right into a heating chamber. An extrusion screw pushes the plastic from the heating chamber, in which the material is softened right into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. After this chamber, the resin is forced at high-pressure in a cooled, closed mold. When the plastic cools to your solid state, the mold opens along with the finished part is ejected. This technique is used to produce products like butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is actually a process used together 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 around the tube and compressed air is then blown into the tube to conform the tube for the interior of the mold as well as to solidify the stretched tube. Overall, the objective is to produce a uniform melt, form it in to a tube with the desired cross section and blow it into the exact shape of the product. This method can be used to manufacture hollow plastic products and its particular principal advantage is its capability to produce hollow shapes while not having to join several separately injection molded parts. This process is 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 and then to heat the preform and blow the temperature-softened plastic into the final shape in the chilled mold. Here is the process to create carbonated soft drink bottles.
Rotational Molding-Rotational molding includes closed mold attached to a machine effective at rotation on two axes simultaneously. Plastic granules are put inside the mold, which happens to be then heated within an oven to melt the plastic Rotation around both axes distributes the molten plastic in a uniform coating on the inside of the mold up until the part is scheduled by cooling. This method is used to create hollow products, for instance large toys or kayaks.
Durables vs. Non-DurablesAll kinds of plastic merchandise is classified within the plastic industry for being either a durable or non-durable plastic good. These classifications are used to reference a product’s expected life.
Products by using a useful life of three years or higher are known as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products using a useful life of lower than 3 years are often called 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 which makes it suitable for carbonated beverage applications and also other food containers. The fact that it provides high use temperature allows it to be used in applications like heatable pre-prepared food trays. Its heat resistance and microwave transparency make it a perfect heatable film. Furthermore, it finds applications in these 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 used for many packaging applications because it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all kinds of polyethylene, is restricted to those food packaging applications that do not require an oxygen or CO2 barrier. In film form, HDPE can be used in snack food packages and cereal box liners; in blow-molded bottle form, for milk and non-carbonated beverage bottles; and in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it can be useful for packaging many household and also industrial chemicals for example detergents, bleach and acids. General uses of HDPE include injection-molded beverage cases, bread trays in addition to films for grocery sacks and bottles for beverages and household chemicals.
Polyvinyl Chloride (PVC) has excellent transparency, chemical resistance, long-term stability, good weatherability and stable electrical properties. Vinyl products might be broadly divided into rigid and flexible materials. Rigid applications are concentrated in construction markets, including pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings could be associated with its resistance to 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 used in film applications due to its toughness, flexibility and transparency. LDPE includes a low melting point rendering it popular to be used in applications where heat sealing is needed. Typically, LDPE is utilized to produce flexible films such as those utilized for dry cleaned garment bags and produce bags. LDPE can also be accustomed to manufacture some flexible lids and bottles, and it is popular in wire and cable applications for the stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and is also frequently used in packaging. It possesses a high melting point, making it suitable for hot fill liquids. Polypropylene is found in anything 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 salt and acid solutions which can be destructive to metals. Typical applications include ketchup bottles, yogurt containers, medicine bottles, pancake syrup bottles and automobile battery casings.
Polystyrene (PS) is really a versatile plastic which can 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, like in medical and food packaging, in laboratory ware, as well as in certain electronic uses. Expandable Polystyrene (EPS) is commonly extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers like egg crates. EPS is also directly formed into cups and tubs for dry foods like dehydrated soups. Both foamed sheet and molded tubs are used extensively in take-out restaurants for his or her lightweight, stiffness and ideal thermal insulation.
Whether you are mindful of it or otherwise not, plastics play a significant part in your own life. Plastics’ versatility allow them to be applied in from car parts to doll parts, from soft drink bottles for the refrigerators they can be kept in. Through the car you drive to operate within the television you watch in your house, plastics help make your life easier and much better. So how will it be that plastics have grown to be so widely used? How did plastics become the material of choice for numerous varied applications?
The simple fact is that plastics provides the points consumers want and desire at economical costs. Plastics get the unique power to be manufactured in order to meet very specific functional needs for consumers. So maybe there’s another question that’s relevant: What exactly do I want? No matter how you answer this inquiry, plastics can probably match your needs.
If a product is constructed of plastic, there’s a good reason. And odds are the main reason has everything to do with assisting you, the customer, get what you wish: Health. Safety. Performance. and Value. Plastics Have The Ability.
Just look at the changes we’ve seen in the grocery store in recent years: plastic wrap helps keep meat fresh while protecting it from the poking and prodding fingers of your own fellow shoppers; plastic containers mean you can actually lift an economy-size bottle of juice and should you accidentally drop that bottle, it is 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 things you buy. Plastics make portable phones and computers that basically are portable. They guide major appliances-like refrigerators or dishwashers-resist corrosion, last longer and operate more proficiently. Plastic car fenders and the body panels resist dings, so you can cruise the food market parking lot with confidence.
Modern packaging-such as heat-sealed plastic pouches and wraps-helps keep food fresh and free from contamination. Which means the resources that went into producing that food aren’t wasted. It’s the same thing when you get the food home: plastic wraps and resealable containers keep your leftovers protected-much for the chagrin of kids everywhere. In fact, packaging experts have estimated that each pound of plastic packaging can reduce food waste by around 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 your beverage including juice, soda or water. You’d need 3 pounds of aluminum to bring home the same amount of product, 8 pounds of steel or over 40 pounds of glass. Not only do plastic bags require less total energy to make than paper bags, they conserve fuel in shipping. It takes seven trucks to carry a similar variety of paper bags as fits in one truckload of plastic bags. Plastics make packaging better, which ultimately conserves resources.
LightweightingPlastics engineers will almost always be trying to do a lot more with less material. Since 1977, the two-liter plastic soft drink bottle went from weighing 68 grams to simply 47 grams today, representing a 31 percent reduction per bottle. That saved more than 180 million pounds of packaging in 2006 only for 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone a comparable reduction, weighing 30 percent less than what it did 20 years ago.
Doing more with less helps conserve resources in yet another way. It helps save energy. Actually, plastics can play a substantial role in energy conservation. Just glance at the decision you’re asked to make at the food market checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less fresh water than does paper bag manufacture. Not only do plastic bags require less total production energy to make than paper bags, they conserve fuel in shipping. It requires seven trucks to hold the same number of paper bags as suits one truckload of plastic bags.
Plastics also assist to conserve energy at home. Vinyl siding and windows help cut energy consumption minimizing air conditioning bills. Furthermore, the U.S. Department of Energy estimates designed to use of plastic foam insulation in homes and buildings each and every year could save over 60 million barrels of oil over other sorts of insulation.
The identical principles apply in appliances for example refrigerators and air conditioners. Plastic parts and insulation have helped to further improve their energy efficiency by 30 to one half because the early 1970s. Again, this energy savings helps reduce your heating and cooling bills. And appliances run more quietly than earlier designs that used many other materials.
Recycling of post-consumer plastics packaging began during the early 1980s because of state level bottle deposit programs, which produced a consistent source of returned PETE bottles. With adding HDPE milk jug recycling in the late 1980s, plastics recycling has grown steadily but in accordance with competing packaging materials.
Roughly 60 % from the U.S. population-about 148 million people-have accessibility to a plastics recycling program. The 2 common forms of collection are: curbside collection-where consumers place designated plastics inside 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 place their recyclables to some centrally located facility (12,000). Most curbside programs collect a couple of kind of plastic resin; usually both PETE and HDPE. Once collected, the plastics are sent 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 in which the plastics are chopped into flakes, washed to eliminate contaminants and sold to terminate users to manufacture new products for example bottles, containers, clothing, carpet, pvc compound, etc. The amount of companies handling and reclaiming post-consumer plastics today has finished 5 times more than in 1986, growing from 310 companies to 1,677 in 1999. The number of end uses of 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 decrease in landfill capacity spurred efforts by legislators to mandate using recycled materials. Mandates, as a technique of expanding markets, may be troubling. Mandates may fail to take health, safety and gratifaction attributes into account. Mandates distort the economic decisions and can result in sub optimal financial results. Moreover, they are not able to acknowledge the life span cycle benefits associated with options to environmental surroundings, for example the efficient consumption of energy and natural resources.
Pyrolysis involves heating plastics within the absence or near lack of oxygen to destroy 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 known as synthesis gas, or syngas). Unlike pyrolysis, combustion is surely an oxidative procedure that generates heat, carbon dioxide, and water.
Chemical recycling can be a special case where condensation polymers for example PET or nylon are chemically reacted to make starting materials.
Source ReductionSource reduction is gaining more attention as an important resource conservation and solid waste management option. Source reduction, also known as “waste prevention” is described as “activities to minimize the quantity of material in products and packaging before that material enters the municipal solid waste management system.”