This was designed to lend a better understanding concerning how plastics are manufactured, the various kinds of plastic in addition to their numerous properties and applications.
A plastic is a kind of synthetic or man-made polymer; similar in many ways to natural resins present in trees and other plants. Webster’s Dictionary defines polymers as: some of various complex organic compounds produced by polymerization, competent at being molded, extruded, cast into various shapes and films, or drawn into filaments after which used as textile fibers.
A Little Bit HistoryThe past of manufactured plastics dates back more than 100 years; however, in comparison with many other materials, plastics are relatively modern. Their usage over the past century has enabled society to create huge technological advances. Although plastics are thought of as an advanced invention, there have been “natural polymers” for example amber, tortoise shells and animal horns. These materials behaved similar to today’s manufactured plastics and were often used the same as the way manufactured plastics are currently applied. By way of 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 1st man-made plastic in the 1862 Great International Exhibition in London. This material-which had been dubbed Parkesine, now called celluloid-was an organic material produced from cellulose that when heated could be molded but retained its shape when cooled. Parkes claimed that the new material could do anything that rubber was capable of, yet for less money. He had discovered a material that might be transparent and also carved into a large number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to produce a synthetic varnish, stumbled upon the formula for a new synthetic polymer originating from coal tar. He subsequently named the brand new substance “Bakelite.” Bakelite, once formed, could not really melted. Due to its properties as an electrical insulator, Bakelite was utilized in the creation of high-tech objects including cameras and telephones. It was actually also utilized in the creation of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” as the term to illustrate this completely new group 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 following the First World War, with the use of petroleum, a substance quicker to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal throughout the hardship times during the 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. Many more would follow and also the 1960s, plastics were within everyone’s reach due to their inexpensive cost. Plastics had thus come to be considered ‘common’-a symbol from the consumer society.
Considering that the 1970s, we have now witnessed the arrival 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 to be developed.
From daily tasks to our own most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs whatsoever levels. Plastics are employed in such a wide array of applications because they are uniquely effective at offering numerous properties that offer consumer benefits unsurpassed by many other materials. They are also unique in this their properties can be customized for each and every individual end use application.
Oil and gas are the major raw materials accustomed to manufacture plastics. The plastics production process often begins by treating parts of oil or gas in a “cracking process.” This technique leads to the conversion of the components into hydrocarbon monomers including ethylene and propylene. Further processing leads to a wider array of monomers including styrene, rigid pvc compound, ethylene glycol, terephthalic acid and others. These monomers are then chemically bonded into chains called polymers. The numerous combinations of monomers yield plastics with a wide array of properties and characteristics.
PlasticsMany common plastics are manufactured from hydrocarbon monomers. These plastics are produced by linking many monomers together into long chains to form a polymer backbone. Polyethylene, polypropylene and polystyrene are the most prevalent instances of these. Below can be a diagram of polyethylene, the most basic plastic structure.
Whilst the basic makeup of countless plastics is carbon and hydrogen, other elements can even 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, 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 will result in the content to decompose as opposed to melt. Bakelite, poly phenol formaldehyde, is actually a thermoset.
Each plastic has very distinct characteristics, but most plastics have the following general attributes.
Plastics are often very proof against chemicals. Consider all the cleaning fluids at home that happen to be packaged in plastic. The warning labels describing what happens once the chemical makes experience of skin or eyes or is 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 may be both thermal and electrical insulators. A walk by your house will reinforce this concept. Consider all the electrical appliances, cords, outlets and wiring which are made or covered with plastics. Thermal resistance is evident in your kitchen 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 consists of polypropylene and also the fiberfill in many winter jackets is acrylic or polyester.
Generally, plastics are really lightweight with varying degrees of strength. Consider the plethora of applications, from toys to 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, when compared to density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics may be processed in a variety of approaches to produce thin fibers or very intricate parts. Plastics can be molded into bottles or elements of cars, including dashboards and fenders. Some pvcppellet stretch and they are very flexible. Other plastics, such as polyethylene, polystyrene (Styrofoam™) and polyurethane, may be foamed. Plastics may be molded into drums or perhaps be combined with solvents in becoming adhesives or paints. Elastomers and a few plastics stretch and therefore are very flexible.
Polymers are materials by using a seemingly limitless range of characteristics and colours. Polymers have several inherent properties that could be further enhanced by a wide array of additives to broaden their uses and applications. Polymers can be made to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers can also make possible products which do not readily range from natural world, like clear sheets, foamed insulation board, and flexible films. Plastics could be molded or formed to produce many different types of products with application in several major markets.
Polymers are generally manufactured from petroleum, but not always. Many polymers are constructed with repeat units produced from gas or coal or oil. But foundation repeat units can often be produced from renewable materials such as polylactic acid from corn or cellulosics from cotton linters. Some plastics have always been made out of renewable materials including cellulose acetate used for screwdriver handles and gift ribbon. When the building blocks can be created more economically from renewable materials than from energy sources, either old plastics find new raw materials or new plastics are introduced.
Many plastics are combined with additives since 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 utilized to protect plastics in the degrading results of light, heat, or bacteria; to modify such plastic properties, including melt flow; to offer color; to supply foamed structure; to provide flame retardancy; and to provide special characteristics including improved surface appearance or reduced tack/friction.
Plasticizers are materials included in certain plastics to improve flexibility and workability. Plasticizers are normally found in numerous plastic film wraps and in flexible plastic tubing, each of which are commonly utilized in food packaging or processing. All plastics found in food contact, including the additives and plasticizers, are regulated with the Usa Food and Drug Administration (FDA) to ensure that these materials are secure.
Processing MethodsThere are many different processing methods used to make plastic products. Listed below are the four main methods in which plastics are processed to create the products that consumers use, including plastic film, bottles, bags as well as other containers.
Extrusion-Plastic pellets or granules are first loaded right into a hopper, then fed into an extruder, which 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 combination of heat in the mechanical work done and also by the recent sidewall metal. At the end of the extruder, the molten plastic needs out via a small opening or die to shape the finished product. Because 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 a hopper in a heating chamber. An extrusion screw pushes the plastic from the heating chamber, the location where the material is softened into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. After this chamber, the resin is forced at high pressure right into a cooled, closed mold. As soon as the plastic cools to some solid state, the mold opens along with the finished part is ejected. This technique is commonly used to make 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 a single 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 towards the interior of your mold and also to solidify the stretched tube. Overall, the target is to generate a uniform melt, form it in a tube using the desired cross section and blow it in to the exact form of the item. This process is utilized to manufacture hollow plastic products and its principal advantage is being able to produce hollow shapes while not having to join 2 or more separately injection molded parts. This process is utilized to help make items like commercial drums and milk bottles. Another blow molding strategy is to injection mold an intermediate shape referred to as a preform and after that to heat the preform and blow the warmth-softened plastic in the final shape inside a chilled mold. This is basically the process to help make carbonated soft drink bottles.
Rotational Molding-Rotational molding is made up of closed mold mounted on a device able to rotation on two axes simultaneously. Plastic granules are put from the mold, which is then heated within an oven to melt the plastic Rotation around both axes distributes the molten plastic into a uniform coating on the inside of the mold until the part is defined by cooling. This method is utilized to help make hollow products, as an example large toys or kayaks.
Durables vs. Non-DurablesAll kinds of plastic products are classified within the plastic industry for being either a durable or non-durable plastic good. These classifications are employed to talk about a product’s expected life.
Products with a useful lifetime of 3 years or even more are called durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products by using a useful lifetime of below 3 years 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 apparent, tough and it has good gas and moisture barrier properties rendering it well suited for carbonated beverage applications along with other food containers. The point that it has high use temperature allows so that it is utilized in applications including heatable pre-prepared food trays. Its heat resistance and microwave transparency ensure it is an ideal 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 most packaging applications as it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like a variety of polyethylene, is restricted to the people 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 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 as well as industrial chemicals including detergents, bleach and acids. General uses of HDPE include injection-molded beverage cases, bread trays and also 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 could be broadly separated into rigid and flexible materials. Rigid applications are concentrated in construction markets, consisting of pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings could be attributed to its potential to deal with most chemicals, imperviousness to attack by bacteria or micro-organisms, corrosion resistance and strength. Flexible vinyl is 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 because of its toughness, flexibility and transparency. LDPE includes a low melting point making it popular to use in applications where heat sealing is important. Typically, LDPE can be used to manufacture flexible films for example those used for dry cleaned garment bags and provide bags. LDPE is likewise employed to manufacture some flexible lids and bottles, in fact it is commonly used in wire and cable applications because of its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance which is frequently used in packaging. It features a high melting point, so that it is perfect for hot fill liquids. Polypropylene is found in anything from flexible and rigid packaging to fibers for fabrics and carpets and big molded parts for automotive and consumer products. Like other plastics, polypropylene has excellent effectiveness against water as well as to 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 a versatile plastic that could be rigid or foamed. General purpose polystyrene is clear, hard and brittle. Its clarity allows it to be used when transparency is essential, as with medical and food packaging, in laboratory ware, and also in certain electronic uses. Expandable Polystyrene (EPS) is often extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers for example egg crates. EPS is additionally directly formed into cups and tubs for dry foods such as dehydrated soups. Both foamed sheet and molded tubs are used extensively in take-out restaurants for lightweight, stiffness and excellent thermal insulation.
Whether you are conscious of it or not, plastics play a crucial part in your daily life. Plastics’ versatility permit them to be applied in anything from car parts to doll parts, from soft drink bottles on the refrigerators these are held in. From the car you drive to work in the television you watch in your house, plastics make your life easier and better. So how would it be that plastics have become so commonly used? How did plastics become the material preferred by so many varied applications?
The easy fact is that plastics provides the items consumers want and require at economical costs. Plastics possess the unique capability 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? Regardless of how you answer this query, plastics can probably suit your needs.
In case a product is made from plastic, there’s a good reason. And chances are the main reason has everything concerning helping you, 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 market recently: plastic wrap assists in keeping meat fresh while protecting it from the poking and prodding fingers of your fellow shoppers; plastic bottles mean you can easily lift an economy-size bottle of juice and must you accidentally drop that bottle, it can be shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also assist you in getting maximum value from some of the big-ticket things you buy. Plastics help make portable phones and computers that truly are portable. They guide major appliances-like refrigerators or dishwashers-resist corrosion, go longer and operate more efficiently. Plastic car fenders and body panels resist dings, so you can cruise the food market car park with full confidence.
Modern packaging-like heat-sealed plastic pouches and wraps-helps keep food fresh and free from contamination. This means the time that went into producing that food aren’t wasted. It’s exactly the same thing as soon as you have 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 can reduce food waste by approximately 1.7 pounds.
Plastics will 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 bring home the equivalent amount of product, 8 pounds of steel or older 40 pounds of glass. Not only do plastic bags require less total energy to create than paper bags, they conserve fuel in shipping. It will take seven trucks to carry the identical amount of paper bags as fits in one truckload of plastic bags. Plastics make packaging more effective, which ultimately conserves resources.
LightweightingPlastics engineers are usually trying to do a lot more with less material. Since 1977, the two-liter plastic soft drink bottle went from weighing 68 grams just to 47 grams today, representing a 31 percent reduction per bottle. That saved over 180 million pounds of packaging in 2006 for only 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone a comparable reduction, weighing 30 percent under exactly what it did twenty years ago.
Doing more with less helps conserve resources in a different way. It helps save energy. In reality, plastics can start to play a significant role in energy conservation. Just consider the decision you’re asked to make in the supermarket checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less freshwater than does paper bag manufacture. Not only do plastic bags require less total production energy to generate than paper bags, they conserve fuel in shipping. It requires seven trucks to handle a similar amount of paper bags as suits one truckload of plastic bags.
Plastics also help to conserve energy in your home. Vinyl siding and windows help cut energy consumption and minimize heating and air conditioning bills. Furthermore, the Usa Department of Energy estimates that use of plastic foam insulation in homes and buildings annually could save over 60 million barrels of oil over other sorts of insulation.
The same principles apply in appliances such as refrigerators and air conditioners. Plastic parts and insulation have helped to enhance their energy efficiency by 30 to fifty percent ever since the early 1970s. Again, this energy savings helps reduce your 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 source of returned PETE bottles. With the addition of HDPE milk jug recycling within the late 1980s, plastics recycling has exploded steadily but in accordance with competing packaging materials.
Roughly 60 percent of the United states population-about 148 million people-have accessibility to a plastics recycling program. Both the common forms of collection are: curbside collection-where consumers place designated plastics in the special bin to be found with a public or private hauling company (approximately 8,550 communities be involved in curbside recycling) and drop-off centers-where consumers get their recyclables to a centrally located facility (12,000). Most curbside programs collect multiple form 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 boost product value. The sorted plastics are then baled to reduce shipping costs to reclaimers.
Reclamation is the next thing in which the plastics are chopped into flakes, washed to get rid of contaminants and sold to terminate users to produce new products like bottles, containers, clothing, carpet, pvc compound, etc. The volume of companies handling and reclaiming post-consumer plastics today is over 5 times greater than in 1986, growing from 310 companies to 1,677 in 1999. The number 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 over the perceived lowering of landfill capacity spurred efforts by legislators to mandate the application of recycled materials. Mandates, as a way of expanding markets, could be troubling. Mandates may neglect to take health, safety and performance attributes into mind. Mandates distort the economic decisions and can cause sub optimal financial results. Moreover, they are not able to acknowledge the lifestyle cycle benefits associated with alternatives to the planet, like the efficient utilization of energy and natural resources.
Pyrolysis involves heating plastics in the absence or near absence of oxygen to interrupt along the long polymer chains into small molecules. Under mild conditions polyolefins can yield a petroleum-like oil. Special conditions can yield monomers like ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and carbon monoxide are known as synthesis gas, or syngas). In contrast to pyrolysis, combustion is surely an oxidative procedure that generates heat, carbon dioxide, and water.
Chemical recycling can be a special case where condensation polymers including PET or nylon are chemically reacted to produce starting materials.
Source ReductionSource reduction is gaining more attention for an important resource conservation and solid waste management option. Source reduction, typically referred to as “waste prevention” is described as “activities to lower the amount of material in products and packaging before that material enters the municipal solid waste management system.”