This was designed to lend a greater understanding concerning how plastics are created, the different types of plastic along with their numerous properties and applications.
A plastic the type of synthetic or man-made polymer; similar in lots of ways to natural resins present in trees and also other plants. Webster’s Dictionary defines polymers as: any one of various complex organic compounds produced by polymerization, effective at being molded, extruded, cast into various shapes and films, or drawn into filaments after which used as textile fibers.
Just A Little HistoryThe past of manufactured plastics goes back more than 100 years; however, when compared with other materials, plastics are relatively modern. Their usage over the past century has allowed society to make huge technological advances. Although plastics are looked at as a modern 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 presently applied. As an example, ahead of the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes utilized to replace glass.
Alexander Parkes unveiled the 1st man-made plastic with the 1862 Great International Exhibition in the uk. This product-which was dubbed Parkesine, now called celluloid-was an organic material produced from cellulose that after heated may be molded but retained its shape when cooled. Parkes claimed this new material could do just about anything that rubber was able to, yet at a lower price. He had discovered a material that may be transparent along with carved into thousands of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to generate a synthetic varnish, came across the formula to get a new synthetic polymer caused by coal tar. He subsequently named the latest substance “Bakelite.” Bakelite, once formed, could not really melted. Due to its properties as an electrical insulator, Bakelite was utilized in the production of high-tech objects including cameras and telephones. It was actually also used in the creation of ashtrays and as a substitute for jade, marble and amber. By 1909, Baekland had coined “plastics” as being the term to clarify this completely new class of materials.
The initial patent for pvc compound, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane had also been discovered during this period.
Plastics failed to really take off until once the First World War, with the aid of petroleum, a substance simpler to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal through the hardship times of World War’s I & II. After The Second World War, newer plastics, for example 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’-a symbol of the consumer society.
Since the 1970s, we certainly have witnessed the arrival of ‘high-tech’ plastics used in demanding fields like health insurance and technology. New types and forms of plastics with new or improved performance characteristics continue to be developed.
From daily tasks to the most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs whatsoever levels. Plastics are utilized in these a wide array of applications because they are uniquely capable of offering numerous properties that offer consumer benefits unsurpassed by other materials. Also, they are unique because their properties can be customized for every individual end use application.
Oil and gas would be the major raw materials used to manufacture plastics. The plastics production process often begins by treating elements of crude oil or gas within a “cracking process.” This procedure brings about the conversion of such components into hydrocarbon monomers such as ethylene and propylene. Further processing leads to a wider array of monomers like styrene, rigid pvc compound, ethylene glycol, terephthalic acid and many others. These monomers are then chemically bonded into chains called polymers. The many mixtures of monomers yield plastics with a variety 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 common types of these. Below is a diagram of polyethylene, the simplest plastic structure.
However the basic makeup of several plastics is carbon and hydrogen, other elements can even be involved. Oxygen, chlorine, fluorine and nitrogen can also be located in the molecular makeup of many 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. Nearly all plastics are thermoplastic, which means that after the plastic is created it might be heated and reformed repeatedly. Celluloid is a thermoplastic. This property allows for easy processing and facilitates recycling. One other group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating will cause the information to decompose as opposed to melt. Bakelite, poly phenol formaldehyde, is actually a thermoset.
Each plastic has very distinct characteristics, but most plastics possess the following general attributes.
Plastics can be quite proof against chemicals. Consider every one of the cleaning fluids at your residence that happen to be packaged in plastic. The warning labels describing what occurs when the chemical comes into experience of skin or eyes or maybe ingested, emphasizes the chemical resistance of such materials. While solvents easily dissolve some plastics, other plastics provide safe, non-breakable packages for aggressive solvents.
Plastics might be both thermal and electrical insulators. A walk by your house will reinforce this idea. Consider all of the electrical appliances, cords, outlets and wiring which can be 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 numerous skiers wear is made of polypropylene and the fiberfill in numerous winter jackets is acrylic or polyester.
Generally, plastics are really light-weight 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®, that is utilized in bulletproof vests. Some polymers float in water although some sink. But, in comparison to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics might be processed in several approaches to produce thin fibers or very intricate parts. Plastics might be molded into bottles or aspects of cars, like dashboards and fenders. Some pvcppellet stretch and so are very flexible. Other plastics, including polyethylene, polystyrene (Styrofoam™) and polyurethane, could be foamed. Plastics might be molded into drums or be mixed with solvents in becoming adhesives or paints. Elastomers and some plastics stretch and are very flexible.
Polymers are materials with a seemingly limitless array of characteristics and colors. Polymers have many inherent properties which can be further enhanced by a variety 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 that do not readily range from natural world, for example clear sheets, foamed insulation board, and flexible films. Plastics may be molded or formed to generate many kinds of products with application in numerous major markets.
Polymers tend to be manufactured from petroleum, however, not always. Many polymers are created from repeat units derived from natural gas or coal or crude 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 created from renewable materials for example cellulose acetate used for screwdriver handles and gift ribbon. If the building blocks 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 incorporated into plastics to change and enhance their basic mechanical, physical, or chemical properties. Additives are used to protect plastics in the degrading outcomes of light, heat, or bacteria; to modify such plastic properties, for example melt flow; to supply color; to provide foamed structure; to deliver flame retardancy; and also to provide special characteristics like improved surface appearance or reduced tack/friction.
Plasticizers are materials integrated into certain plastics to improve flexibility and workability. Plasticizers are located in several plastic film wraps and in flexible plastic tubing, each of which are generally employed in food packaging or processing. All plastics employed in food contact, including the additives and plasticizers, are regulated through the U.S. Food and Drug Administration (FDA) to ensure these materials are safe.
Processing MethodsThere are some different processing methods employed to make plastic products. Below are the 4 main methods by which plastics are processed to make the products that consumers use, for example plastic film, bottles, bags along with other containers.
Extrusion-Plastic pellets or granules are first loaded in to a hopper, then fed into an extruder, which is actually a long heated chamber, whereby it really 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 also the hot sidewall metal. At the end of the extruder, the molten plastic needs out using a small opening or die to shape the finished product. As the plastic product extrudes from your die, it really is 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 right into a heating chamber. An extrusion screw pushes the plastic from the heating chamber, where the material is softened into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. After this chamber, the resin needs at high-pressure in a cooled, closed mold. When the plastic cools to some solid state, the mold opens and also the finished part is ejected. This method is used to make products such as butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is actually a process used together with extrusion or injection molding. In just one form, extrusion blow molding, the die forms a continuous semi-molten tube of thermoplastic material. A chilled mold is clamped around the tube and compressed air is then blown into the tube to conform the tube on the interior from the mold and to solidify the stretched tube. Overall, the aim is to produce a uniform melt, form it into a tube together with the desired cross section and blow it to the exact model of this product. This technique can be used to manufacture hollow plastic products and its particular principal advantage is its ability to produce hollow shapes while not having to join several separately injection molded parts. This method is used to make items for example commercial drums and milk bottles. Another blow molding method is to injection mold an intermediate shape called a preform after which to heat the preform and blow the high temperature-softened plastic to the final shape within a chilled mold. This is actually the process to help make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes closed mold attached to a unit capable of rotation on two axes simultaneously. Plastic granules are put in the mold, that is then heated in a oven to melt the plastic Rotation around both axes distributes the molten plastic in a uniform coating on the inside of the mold till the part is defined by cooling. This technique is utilized to produce hollow products, by way of example large toys or kayaks.
Durables vs. Non-DurablesAll kinds of plastic items are classified in the plastic industry to be either a durable or non-durable plastic good. These classifications are employed to reference a product’s expected life.
Products having a useful life of 36 months or even more are referred to as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products with a useful lifetime of less than three years are generally 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 clear, tough and possesses good gas and moisture barrier properties so that it is suitable for carbonated beverage applications along with other food containers. The reality that it provides high use temperature allows it to be utilized in applications including heatable pre-prepared food trays. Its heat resistance and microwave transparency allow it to be an ideal heatable film. In addition, it 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 a lot of packaging applications as it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all types of polyethylene, has limitations 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 then in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it is actually used for packaging many household along with industrial chemicals such as 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, lasting stability, good weatherability and stable electrical properties. Vinyl products could be broadly divided into rigid and versatile materials. Rigid applications are concentrated in construction markets, which includes pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings might be associated with 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 utilized in film applications due to its toughness, flexibility and transparency. LDPE includes a low melting point making it popular to use in applications where heat sealing is needed. Typically, LDPE can be used to produce flexible films like those used for dry cleaned garment bags and create bags. LDPE is additionally accustomed to manufacture some flexible lids and bottles, in fact it is traditionally used in wire and cable applications for the stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and is frequently used in packaging. It comes with a high melting point, so that it is suitable for hot fill liquids. Polypropylene is found 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 potential to deal with water as well as salt and acid solutions which are destructive to metals. Typical applications include ketchup bottles, yogurt containers, medicine bottles, pancake syrup bottles and automobile battery casings.
Polystyrene (PS) is really a versatile plastic which can be rigid or foamed. General purpose polystyrene is clear, hard and brittle. Its clarity allows so that it is used when transparency is very important, as in medical and food packaging, in laboratory ware, and then in certain electronic uses. Expandable Polystyrene (EPS) is normally extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers including egg crates. EPS can also be directly formed into cups and tubs for dry foods like dehydrated soups. Both foamed sheet and molded tubs are utilized extensively in take-out restaurants for lightweight, stiffness and excellent thermal insulation.
If you are aware of it or otherwise, plastics play a significant part in your life. Plastics’ versatility allow them to be applied in from car parts to doll parts, from soft drink bottles on the refrigerators these are kept in. From your car you drive to work in the television you watch in the home, plastics make your life easier and. So how could it be that plastics are getting to be so traditionally used? How did plastics get to be the material preferred by numerous varied applications?
The easy fact is that plastics offers the items consumers want and desire at economical costs. Plastics hold the unique capacity to be manufactured to fulfill very specific functional needs for consumers. So maybe there’s another question that’s relevant: What exactly do I want? Regardless how you answer this, plastics often will match your needs.
When a product is made from plastic, there’s grounds. And chances are the key reason why has everything to do with assisting you, the buyer, get what you wish: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just think about the changes we’ve found in the food store in recent years: plastic wrap assists in keeping meat fresh while protecting it from your poking and prodding fingers of your fellow shoppers; plastic bottles mean you can actually lift an economy-size bottle of juice and must you accidentally drop that bottle, it is shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also assist you in getting maximum value from a number of the big-ticket things you buy. Plastics help make portable phones and computers that actually are portable. They help major appliances-like refrigerators or dishwashers-resist corrosion, last longer and operate more effectively. Plastic car fenders and body panels resist dings, to help you cruise the food market car park with assurance.
Modern packaging-for example heat-sealed plastic pouches and wraps-assists in keeping food fresh and clear of contamination. This means the time that went into producing that food aren’t wasted. It’s the same thing as soon as you have the food home: plastic wraps and resealable containers keep the leftovers protected-much for the chagrin of kids everywhere. Actually, packaging experts have estimated that each pound of plastic packaging is effective in reducing food waste by approximately 1.7 pounds.
Plastics can also help you bring home more product with less packaging. For instance, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of your beverage such as juice, soda or water. You’d need 3 pounds of aluminum to create home the same amount of product, 8 pounds of steel or older 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 transport the same amount of paper bags as fits in one truckload of plastic bags. Plastics make packaging more potent, which ultimately conserves resources.
LightweightingPlastics engineers are usually endeavoring 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 more than 180 million pounds of packaging in 2006 for just 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone a comparable reduction, weighing 30 percent lower than just what it did two decades ago.
Doing more with less helps conserve resources in another way. It may help save energy. In fact, plastics can start to play a significant role in energy conservation. Just consider the decision you’re motivated to make in the food market 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 will require seven trucks to handle exactly the same amount 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 heating and air conditioning bills. Furthermore, the United states 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 kinds of insulation.
The same principles apply in appliances including refrigerators and ac units. Plastic parts and insulation have helped to further improve their energy efficiency by 30 to fifty percent since the early 1970s. Again, this energy savings helps in reducing your heating and air conditioning bills. And appliances run more quietly than earlier designs that used other materials.
Recycling of post-consumer plastics packaging began in early 1980s because of state level bottle deposit programs, which produced a consistent supply of returned PETE bottles. With the addition of HDPE milk jug recycling within the late 1980s, plastics recycling has grown steadily but relative to competing packaging materials.
Roughly 60 percent of the U.S. population-about 148 million people-get access to a plastics recycling program. Both the common sorts of collection are: curbside collection-where consumers place designated plastics in a special bin to get acquired from 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 several 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 improve product value. The sorted plastics are then baled to minimize shipping costs to reclaimers.
Reclamation is the next phase in which the plastics are chopped into flakes, washed to eliminate contaminants and sold to end users to produce new products for example bottles, containers, clothing, carpet, pvc compound, etc. The number of companies handling and reclaiming post-consumer plastics today has ended 5 times in excess of in 1986, growing from 310 companies to 1,677 in 1999. The quantity of end uses for recycled plastics keeps growing. The government and state government as well as many major corporations now support market growth through purchasing preference policies.
Early in the 1990s, concern within the perceived reduction of landfill capacity spurred efforts by legislators to mandate the usage of recycled materials. Mandates, as a means of expanding markets, may be troubling. Mandates may fail to take health, safety and satisfaction attributes into account. Mandates distort the economic decisions and can cause sub optimal financial results. Moreover, they are not able to acknowledge the lifespan cycle benefits associated with alternatives to the surroundings, like the efficient utilization of energy and natural resources.
Pyrolysis involves heating plastics in the absence or near deficiency of oxygen to get rid of along the long polymer chains into small molecules. Under mild conditions polyolefins can yield a petroleum-like oil. Special conditions can yield monomers like ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and carbon monoxide are classified as synthesis gas, or syngas). In contrast to pyrolysis, combustion is undoubtedly an oxidative procedure that generates heat, co2, and water.
Chemical recycling is actually a special case where condensation polymers such as PET or nylon are chemically reacted to make starting materials.
Source ReductionSource reduction is gaining more attention as being an important resource conservation and solid waste management option. Source reduction, also known as “waste prevention” is identified as “activities to reduce the level of material in products and packaging before that material enters the municipal solid waste management system.”