This is designed to lend a greater understanding concerning how plastics are manufactured, the several types of plastic in addition to their numerous properties and applications.
A plastic is a type of synthetic or man-made polymer; similar in several ways to natural resins present in trees and also other plants. Webster’s Dictionary defines polymers as: any one of various complex organic compounds created 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 HistoryThe reputation of manufactured plastics goes back more than a century; however, when compared with other materials, plastics are relatively modern. Their usage within the last century has allowed society to make huge technological advances. Although plastics are considered to be a modern day invention, there have invariably been “natural polymers” such as amber, tortoise shells and animal horns. These materials behaved like today’s manufactured plastics and were often used the same as the way manufactured plastics are currently applied. For instance, 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 very first man-made plastic on the 1862 Great International Exhibition in the uk. This product-that was dubbed Parkesine, now called celluloid-was an organic material derived from cellulose that when heated may be molded but retained its shape when cooled. Parkes claimed that the new material could a single thing that rubber was competent at, yet on the cheap. He had discovered a material that might be transparent along with carved into a huge number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to produce a synthetic varnish, discovered the formula for any new synthetic polymer caused by coal tar. He subsequently named the new substance “Bakelite.” Bakelite, once formed, could not melted. Due to the properties for an electrical insulator, Bakelite was adopted in the creation of high-tech objects including cameras and telephones. It was actually also found in producing ashtrays and as a substitute for jade, marble and amber. By 1909, Baekland had coined “plastics” since the term to illustrate 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 period.
Plastics failed to really remove until right after the First World War, by using petroleum, a substance quicker to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal throughout the hardship days 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. 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 of the consumer society.
Since the 1970s, we have witnessed the arrival of ‘high-tech’ plastics used in demanding fields for example health and technology. New types and sorts of plastics with new or improved performance characteristics continue being developed.
From daily tasks to your most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs at all levels. Plastics are utilized in these a wide array of applications as they are uniquely effective at offering numerous properties that offer consumer benefits unsurpassed by other materials. They are also unique because their properties might be customized for every single individual end use application.
Oil and natural gas will be the major raw materials used to manufacture plastics. The plastics production process often begins by treating components of crude oil or gas in a “cracking process.” This procedure brings about the conversion of those components into hydrocarbon monomers like ethylene and propylene. Further processing leads to a wider selection of monomers like styrene, upvc compound, ethylene glycol, terephthalic acid and others. These monomers are then chemically bonded into chains called polymers. The various combinations of monomers yield plastics with an array of properties and characteristics.
PlasticsMany common plastics are produced from 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 instances of these. Below can be a diagram of polyethylene, the simplest plastic structure.
Even though the basic makeup of many plastics is carbon and hydrogen, other elements can be involved. Oxygen, chlorine, fluorine and nitrogen will also be located in the molecular makeup of several plastics. Polyvinyl chloride (PVC) contains chlorine. Nylon contains nitrogen. Teflon contains fluorine. Polyester and polycarbonates contain oxygen.
Characteristics of Plastics Plastics are divided into two distinct groups: thermoplastics and thermosets. The vast majority of plastics are thermoplastic, which means once the plastic is created it can be heated and reformed repeatedly. Celluloid is a thermoplastic. This property allows for easy processing and facilitates recycling. One other group, the thermosets, cannot be remelted. Once these plastics are formed, reheating may cause the information to decompose as an alternative to melt. Bakelite, poly phenol formaldehyde, can be a thermoset.
Each plastic has very distinct characteristics, but many plastics have the following general attributes.
Plastics are often very immune to chemicals. Consider each of the cleaning fluids in your home which are packaged in plastic. The warning labels describing what will happen as soon as the chemical comes into 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 could be both thermal and electrical insulators. A stroll using your house will reinforce this idea. Consider every one of the electrical appliances, cords, outlets and wiring that are made or covered with plastics. Thermal resistance is evident in the 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 is made from polypropylene as well as the fiberfill in many winter jackets is acrylic or polyester.
Generally, plastics are extremely light-weight with varying degrees of strength. Consider the range 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 and some sink. But, in comparison to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics can be processed in various methods to produce thin fibers or very intricate parts. Plastics can be molded into bottles or aspects of cars, such as dashboards and fenders. Some pvcppellet stretch and are very flexible. Other plastics, for example polyethylene, polystyrene (Styrofoam™) and polyurethane, might be foamed. Plastics could be molded into drums or be mixed with solvents to become adhesives or paints. Elastomers and several plastics stretch and so are very flexible.
Polymers are materials by using a seemingly limitless array of characteristics and colors. Polymers have many inherent properties that could be further enhanced by a wide range of additives to broaden their uses and applications. Polymers can be produced to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers also can make possible products that do not readily come from the natural world, like 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 are often manufactured from petroleum, yet not always. Many polymers are made of repeat units based on natural gas or coal or crude oil. But foundation repeat units can often be made from renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have invariably been made from renewable materials including cellulose acetate utilized for screwdriver handles and gift ribbon. When the foundations can be produced more economically from renewable materials than from energy sources, either old plastics find new raw materials or new plastics are introduced.
Many plastics are blended with additives because they are processed into finished products. The additives are included in plastics to alter and increase their basic mechanical, physical, or chemical properties. Additives are used to protect plastics from your degrading results of light, heat, or bacteria; to modify such plastic properties, including melt flow; to supply color; to offer foamed structure; to provide flame retardancy; and also to provide special characteristics such as improved surface appearance or reduced tack/friction.
Plasticizers are materials integrated into certain plastics to increase flexibility and workability. Plasticizers are found in lots of plastic film wraps and also in flexible plastic tubing, each of which are normally utilized in food packaging or processing. All plastics employed in food contact, like the additives and plasticizers, are regulated with the United states Food and Drug Administration (FDA) to ensure these materials are secure.
Processing MethodsThere are many different processing methods employed to make plastic products. Listed below are the four main methods where plastics are processed to create the products that consumers use, like plastic film, bottles, bags along with 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, by which it is moved by the action of a continuously revolving screw. The plastic is melted by a mixture of heat through the mechanical work done and through the recent sidewall metal. Following the extruder, the molten plastic needs out through a small opening or die to shape the finished product. Since the plastic product extrudes from your die, it can be 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 in to a heating chamber. An extrusion screw pushes the plastic throughout the heating chamber, where 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 to a cooled, closed mold. After the plastic cools to some solid state, the mold opens along with the finished part is ejected. This method can be used to help make products such as butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is actually a process used jointly 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 will then be blown to the tube to conform the tube for the interior from the mold as well as solidify the stretched tube. Overall, the aim is to generate a uniform melt, form it into a tube with all the desired cross section and blow it in to the exact shape of this product. This technique is commonly used to produce hollow plastic products and its principal advantage is its capability to produce hollow shapes and never have to join two or more separately injection molded parts. This method can be used to create items such as commercial drums and milk bottles. Another blow molding strategy is to injection mold an intermediate shape termed as a preform then to heat the preform and blow the temperature-softened plastic to the final shape within a chilled mold. Here is the process to produce carbonated soft drink bottles.
Rotational Molding-Rotational molding consists of a closed mold installed on a piece of equipment able to rotation on two axes simultaneously. Plastic granules are positioned from the mold, which happens to be then heated in a oven to melt the plastic Rotation around both axes distributes the molten plastic in to a uniform coating on the inside of the mold before the part is defined by cooling. This process is commonly used to make hollow products, for example large toys or kayaks.
Durables vs. Non-DurablesAll varieties of plastic products are classified within the plastic industry for being either a durable or non-durable plastic good. These classifications are widely used to reference a product’s expected life.
Products by using a useful life of 3 years or maybe more are called durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products having a useful life of less than 3 years 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 it has good gas and moisture barrier properties which makes it suitable for carbonated beverage applications as well as other food containers. The point that they have high use temperature allows it to be utilized in applications such as heatable pre-prepared food trays. Its heat resistance and microwave transparency make it a perfect 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) can be used for a lot of packaging applications since it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all kinds of polyethylene, is limited to people food packaging applications which 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 is employed for packaging many household in addition to industrial chemicals like 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-term stability, good weatherability and stable electrical properties. Vinyl products can be broadly split 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 may be attributed to its effectiveness against 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 due to its toughness, flexibility and transparency. LDPE includes a low melting point making it popular to be used in applications where heat sealing is necessary. Typically, LDPE is utilized to produce flexible films including those useful for dry cleaned garment bags and create bags. LDPE is likewise accustomed to manufacture some flexible lids and bottles, and is particularly 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 has a high melting point, making it ideal for hot fill liquids. Polypropylene is located in 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 and also 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 actually a versatile plastic which can be rigid or foamed. General purpose polystyrene is obvious, hard and brittle. Its clarity allows so that it is used when transparency is essential, like medical and food packaging, in laboratory ware, and then 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 including dehydrated soups. Both foamed sheet and molded tubs are being used extensively in take-out restaurants for his or her lightweight, stiffness and excellent thermal insulation.
Regardless if you are aware of it or otherwise, plastics play an important part in your lifetime. Plastics’ versatility permit them to be used in anything from car parts to doll parts, from soft drink bottles for the refrigerators they may be saved in. From your car you drive to work in the television you watch in the home, plastics make your life easier and much better. So how is it that plastics are getting to be so widely used? How did plastics end up being the material preferred by countless varied applications?
The straightforward response is that plastics can offer those things consumers want and want at economical costs. Plastics get the unique capability to be manufactured to fulfill very specific functional needs for consumers. So maybe there’s another question that’s relevant: Precisely what do I want? Irrespective of how you answer this, plastics often will match your needs.
If a product is made of plastic, there’s reasons. And chances are the reason why has everything to do with helping you to, the customer, get what you need: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just look at the changes we’ve noticed in the grocery store lately: plastic wrap assists in keeping meat fresh while protecting it through the poking and prodding fingers of the fellow shoppers; plastic containers mean you can easily lift an economy-size bottle of juice and ought to you accidentally drop that bottle, it is shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also help you get maximum value from several 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, go longer and operate more effectively. Plastic car fenders and the entire body panels resist dings, in order to cruise the supermarket parking area with confidence.
Modern packaging-such as heat-sealed plastic pouches and wraps-helps keep food fresh and without any contamination. This means the resources that went into producing that food aren’t wasted. It’s the exact same thing once you have the food home: plastic wraps and resealable containers make your leftovers protected-much on the chagrin of kids everywhere. In reality, packaging experts have estimated that every pound of plastic packaging can reduce food waste by up to 1.7 pounds.
Plastics can also help you bring home more product with less packaging. By way of example, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of a 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 older 40 pounds of glass. Not only do plastic bags require less total energy to make than paper bags, they conserve fuel in shipping. It will require seven trucks to handle exactly the same variety of paper bags as suits one truckload of plastic bags. Plastics make packaging more potent, which ultimately conserves resources.
LightweightingPlastics engineers are always endeavoring to do more with less material. Since 1977, the two-liter plastic soft drink bottle went from weighing 68 grams to just 47 grams today, representing a 31 percent reduction per bottle. That saved greater than 180 million pounds of packaging in 2006 for only 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone an identical reduction, weighing 30 percent under what it really did 20 years ago.
Doing more with less helps conserve resources in a different way. It may help save energy. Actually, plastics can play a significant role in energy conservation. Just consider the decision you’re required to make on the supermarket checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less fresh water than does paper bag manufacture. Furthermore plastic bags require less total production energy to create than paper bags, they conserve fuel in shipping. It takes seven trucks to transport exactly the same quantity of paper bags as fits in one truckload of plastic bags.
Plastics also aid to conserve energy in your home. Vinyl siding and windows help cut energy consumption and minimize air conditioning bills. Furthermore, the U.S. 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 kinds of insulation.
The identical principles apply in appliances including refrigerators and air conditioning units. Plastic parts and insulation have helped to improve their energy efficiency by 30 to one half ever since the early 1970s. Again, this energy savings helps in reducing 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 as a result of state level bottle deposit programs, which produced a consistent availability of returned PETE bottles. With incorporating HDPE milk jug recycling from the late 1980s, plastics recycling continues to grow steadily but relative to competing packaging materials.
Roughly 60 percent in the Usa population-about 148 million people-gain access to a plastics recycling program. The two common forms of collection are: curbside collection-where consumers place designated plastics within a special bin to become found with a public or private hauling company (approximately 8,550 communities take part in curbside recycling) and drop-off centers-where consumers place their recyclables to your centrally located facility (12,000). Most curbside programs collect multiple 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 increase product value. The sorted plastics are then baled to lessen shipping costs to reclaimers.
Reclamation is the next phase the location where the plastics are chopped into flakes, washed to get rid of contaminants and sold to end users to manufacture new items like bottles, containers, clothing, carpet, pvc compound, etc. The amount of companies handling and reclaiming post-consumer plastics today is finished five times more than in 1986, growing from 310 companies to 1,677 in 1999. The number of end ways to use recycled plastics keeps growing. The government and state government along with many major corporations now support market growth through purchasing preference policies.
Early in the 1990s, concern across the perceived lowering of landfill capacity spurred efforts by legislators to mandate the application of recycled materials. Mandates, as a means of expanding markets, could be troubling. Mandates may fail to take health, safety and satisfaction attributes into mind. Mandates distort the economic decisions and can bring about sub optimal financial results. Moreover, they are unable to acknowledge the life span cycle advantages of alternatives to environmental surroundings, for example the efficient use of energy and natural resources.
Pyrolysis involves heating plastics in the absence or near absence of oxygen to break on 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 deadly carbon monoxide are called synthesis gas, or syngas). Contrary to pyrolysis, combustion is an oxidative procedure that generates heat, carbon dioxide, and water.
Chemical recycling is actually a special case where condensation polymers such as 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, often called “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.”