This is designed to lend a much better understanding concerning how plastics are produced, the different types of plastic along with their numerous properties and applications.
A plastic is a form of synthetic or man-made polymer; similar in many ways to natural resins seen in trees as well as other plants. Webster’s Dictionary defines polymers as: any of various complex organic compounds created by polymerization, competent at being molded, extruded, cast into various shapes and films, or drawn into filaments and then used as textile fibers.
A Bit HistoryThe history of manufactured plastics goes back a lot more than a century; however, in comparison to many other materials, plastics are relatively modern. Their usage in the last century has allowed society to produce huge technological advances. Although plastics are thought of as a modern invention, there have been “natural polymers” such as amber, tortoise shells and animal horns. These materials behaved very much like today’s manufactured plastics and were often used just like the way manufactured plastics are currently 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 very first man-made plastic with the 1862 Great International Exhibition in London. This material-that has been dubbed Parkesine, now called celluloid-was an organic material produced by cellulose that after heated could be molded but retained its shape when cooled. Parkes claimed that this new material could do anything that rubber was able to, yet for less money. He had discovered a material that could be transparent along with carved into a huge number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to make a synthetic varnish, came across the formula for the new synthetic polymer originating from coal tar. He subsequently named the new substance “Bakelite.” Bakelite, once formed, could not really melted. Due to its properties as an electrical insulator, Bakelite was applied in producing high-tech objects including cameras and telephones. It was also used in producing ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” since the term to describe this completely new class 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 was discovered during this period.
Plastics did not really take off until after the First World War, with the aid of petroleum, a substance easier 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 2, newer plastics, like polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. More would follow and through the 1960s, plastics were within everyone’s reach due to their inexpensive cost. Plastics had thus come to be considered ‘common’-a symbol in the consumer society.
Since the 1970s, we have witnessed the advent of ‘high-tech’ plastics used in demanding fields including health insurance and technology. New types and types of plastics with new or improved performance characteristics continue being 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 variety of applications since they are uniquely effective at offering many different properties that offer consumer benefits unsurpassed by many other materials. They are also unique for the reason that their properties may be customized for each individual end use application.
Oil and natural gas will be the major raw materials employed to manufacture plastics. The plastics production process often begins by treating parts of oil or gas in the “cracking process.” This technique leads to the conversion of the components into hydrocarbon monomers for example ethylene and propylene. Further processing leads to a wider range of monomers including styrene, soft pvc granule, ethylene glycol, terephthalic acid and many others. These monomers are then chemically bonded into chains called polymers. The numerous combinations of monomers yield plastics with a variety of properties and characteristics.
PlasticsMany common plastics are manufactured 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 typical examples of these. Below is a diagram of polyethylene, the easiest 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 found 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 majority of plastics are thermoplastic, which means that once the plastic is actually created it can be heated and reformed repeatedly. Celluloid can be a thermoplastic. This property provides for easy processing and facilitates recycling. Another group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating can cause the information to decompose as an alternative to melt. Bakelite, poly phenol formaldehyde, is a thermoset.
Each plastic has very distinct characteristics, but the majority plastics possess the following general attributes.
Plastics can be very resistant against chemicals. Consider all of the cleaning fluids at home which can be packaged in plastic. The warning labels describing what will happen if the chemical enters into contact with skin or eyes or maybe 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 using your house will reinforce this concept. Consider all of the electrical appliances, cords, outlets and wiring which can 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 is made from polypropylene as well as the fiberfill in several winter jackets is acrylic or polyester.
Generally, plastics are very light in weight with varying degrees of strength. Consider the range 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 although 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 parts of cars, like dashboards and fenders. Some pvcppellet stretch and so are very flexible. Other plastics, like polyethylene, polystyrene (Styrofoam™) and polyurethane, could be foamed. Plastics may be molded into drums or even be mixed with solvents to get adhesives or paints. Elastomers plus some plastics stretch and therefore are very flexible.
Polymers are materials with a seemingly limitless range of characteristics and colors. Polymers have numerous inherent properties which can be further enhanced by a wide 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 can also make possible products which do not readily range from natural world, like clear sheets, foamed insulation board, and versatile films. Plastics could be molded or formed to make many different types of products with application in numerous major markets.
Polymers are usually manufactured from petroleum, although not always. Many polymers are constructed with repeat units derived from natural gas or coal or crude oil. But building block repeat units can sometimes be made from renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have been produced from renewable materials such as cellulose acetate useful 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 combined with additives as they are processed into finished products. The additives are included in plastics to change and boost their basic mechanical, physical, or chemical properties. Additives are used to protect plastics in the degrading outcomes of light, heat, or bacteria; to change such plastic properties, including melt flow; to supply color; to supply foamed structure; to deliver flame retardancy; and also to provide special characteristics like improved surface appearance or reduced tack/friction.
Plasticizers are materials included in certain plastics to improve flexibility and workability. Plasticizers can be found in many plastic film wraps and then in flexible plastic tubing, each of which are commonly utilized in food packaging or processing. All plastics employed in food contact, like the additives and plasticizers, are regulated from the Usa Food and Drug Administration (FDA) to ensure that these materials are secure.
Processing MethodsThere are several different processing methods accustomed to make plastic products. Here are the four main methods by which plastics are processed to create the products that consumers use, for example plastic film, bottles, bags and other containers.
Extrusion-Plastic pellets or granules are first loaded in to a hopper, then fed into an extruder, which is a long heated chamber, in which it is moved by the act of a continuously revolving screw. The plastic is melted by a mixture of heat from your mechanical work done and also the new sidewall metal. After the extruder, the molten plastic needs out via a small opening or die to shape the finished product. Because the plastic product extrudes in the 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 coming from a hopper into a heating chamber. An extrusion screw pushes the plastic through the heating chamber, in which the material is softened right into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. Following this chamber, the resin needs at high pressure right into a cooled, closed mold. As soon as the plastic cools into a solid state, the mold opens and also the finished part is ejected. This technique can be used to produce products including 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 round the tube and compressed air will then be blown into the tube to conform the tube towards the interior of your mold as well as to solidify the stretched tube. Overall, the goal is to generate a uniform melt, form it into a tube together with the desired cross section and blow it into the exact model of the item. This procedure is used to produce hollow plastic products as well as its principal advantage is being able to produce hollow shapes while not having to join several separately injection molded parts. This method is utilized to create items for example commercial drums and milk bottles. Another blow molding strategy is to injection mold an intermediate shape called a preform then to heat the preform and blow the heat-softened plastic in the final shape inside a chilled mold. Here is the process to make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes a closed mold placed on a piece of equipment competent at rotation on two axes simultaneously. Plastic granules are put within the mold, which is then heated in a oven to melt the plastic Rotation around both axes distributes the molten plastic into a uniform coating on the inside of the mold till the part is defined by cooling. This method is commonly used to create hollow products, for instance large toys or kayaks.
Durables vs. Non-DurablesAll varieties of plastic merchandise is classified throughout the plastic industry for being either a durable or non-durable plastic good. These classifications are utilized to make reference to a product’s expected life.
Products using a useful lifetime of 3 years or more are termed as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products having a useful lifetime of under three years are usually 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 apparent, tough and has good gas and moisture barrier properties making it ideal for carbonated beverage applications and also other food containers. The fact that it provides high use temperature allows that it is found in applications such as heatable pre-prepared food trays. Its heat resistance and microwave transparency ensure it is 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) is used for most packaging applications mainly because it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all kinds of polyethylene, has limitations to the people 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 really is useful for packaging many household as well as industrial chemicals for example detergents, bleach and acids. General uses of HDPE include injection-molded beverage cases, bread trays as well as 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 split up 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 might be associated with its resistance to 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 used in film applications due to the toughness, flexibility and transparency. LDPE includes a low melting point which makes it popular for use in applications where heat sealing is needed. Typically, LDPE is commonly used to manufacture flexible films for example those utilized for dry cleaned garment bags and produce bags. LDPE can also be utilized to manufacture some flexible lids and bottles, in fact it is popular in wire and cable applications due to its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and is also popular in packaging. It possesses a high melting point, rendering it well suited for hot fill liquids. Polypropylene is located in everything 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 effectiveness against 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) can be a versatile plastic that could be rigid or foamed. General purpose polystyrene is apparent, hard and brittle. Its clarity allows so that it is used when transparency is important, 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 including egg crates. EPS can also be directly formed into cups and tubs for dry foods such as dehydrated soups. Both foamed sheet and molded tubs are being used extensively in take-out restaurants for his or her lightweight, stiffness and ideal thermal insulation.
If you are mindful of it or perhaps not, plastics play a significant part in your own life. Plastics’ versatility let them be applied in anything from car parts to doll parts, from soft drink bottles towards the refrigerators they are stored in. From your car you drive to operate into the television you watch at home, plastics make your life easier and better. So how will it be that plastics have become so traditionally used? How did plastics get to be the material preferred by numerous varied applications?
The simple response is that plastics offers the points consumers want and need at economical costs. Plastics possess 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: Precisely what do I want? Regardless how you answer this inquiry, plastics can probably suit your needs.
If a product is made from plastic, there’s a reason. And chances are the key reason why has everything related to helping you to, the customer, get what you need: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just take into account the changes we’ve noticed in the food market lately: plastic wrap assists in keeping meat fresh while protecting it through the poking and prodding fingers of the fellow shoppers; plastic bottles mean you could 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 aid you in getting maximum value from a few of the big-ticket stuff you buy. Plastics make portable phones and computers that really are portable. They guide major appliances-like refrigerators or dishwashers-resist corrosion, last longer and operate more effectively. Plastic car fenders and body panels resist dings, so that you can cruise the grocery store parking lot with assurance.
Modern packaging-for example heat-sealed plastic pouches and wraps-assists in keeping food fresh and free from contamination. This means the resources that went into producing that food aren’t wasted. It’s the same after you get the food home: plastic wraps and resealable containers maintain your leftovers protected-much for the chagrin of kids everywhere. In reality, packaging experts have estimated that each pound of plastic packaging helps to reduce food waste by approximately 1.7 pounds.
Plastics will 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 any beverage such as juice, soda or water. You’d need 3 pounds of aluminum to take 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 produce than paper bags, they conserve fuel in shipping. It will require seven trucks to hold the identical number of paper bags as suits one truckload of plastic bags. Plastics make packaging better, which ultimately conserves resources.
LightweightingPlastics engineers will always be attempting to do a lot more with less material. Since 1977, the 2-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 just 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone the same reduction, weighing 30 percent lower than exactly what it did two decades ago.
Doing more with less helps conserve resources in another way. It may help save energy. Actually, plastics may play an important role in energy conservation. Just check out the decision you’re motivated to make on the grocery store checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less freshwater than does paper bag manufacture. In addition plastic bags require less total production energy to create than paper bags, they conserve fuel in shipping. It will take seven trucks to hold the identical quantity of paper bags as suits one truckload of plastic bags.
Plastics also assist to conserve energy in your home. Vinyl siding and windows help cut energy consumption minimizing air conditioning bills. Furthermore, the Usa 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 sorts of insulation.
The identical principles apply in appliances including refrigerators and ac units. Plastic parts and insulation have helped to improve their energy efficiency by 30 to 50 % 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 on account of state level bottle deposit programs, which produced a consistent source of returned PETE bottles. With adding HDPE milk jug recycling inside the late 1980s, plastics recycling continues to grow steadily but relative to competing packaging materials.
Roughly 60 % from the United states population-about 148 million people-gain access to a plastics recycling program. Both common forms of collection are: curbside collection-where consumers place designated plastics in a special bin to get picked up from a public or private hauling company (approximately 8,550 communities take part in curbside recycling) and drop-off centers-where consumers take their recyclables to some centrally located facility (12,000). Most curbside programs collect more than one form of plastic resin; usually both PETE and HDPE. Once collected, the plastics are transported 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 lower shipping costs to reclaimers.
Reclamation is the next step where the plastics are chopped into flakes, washed to get rid of contaminants and sold to terminate users to produce new releases such as bottles, containers, clothing, carpet, clear pvc granule, etc. The number of companies handling and reclaiming post-consumer plastics today is finished 5 times in excess of in 1986, growing from 310 companies to 1,677 in 1999. The number of end purposes of recycled plastics keeps growing. The federal and state government in addition to 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 the use of recycled materials. Mandates, as a method of expanding markets, may be troubling. Mandates may forget to take health, safety and gratifaction attributes under consideration. Mandates distort the economic decisions and can result in sub optimal financial results. Moreover, they are unable to acknowledge the life span cycle advantages of choices to the environment, including the efficient use of energy and natural resources.
Pyrolysis involves heating plastics inside the absence or near shortage of oxygen to destroy down 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 deadly carbon monoxide are classified as synthesis gas, or syngas). Contrary to pyrolysis, combustion is surely an oxidative method that generates heat, co2, and water.
Chemical recycling is 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 as an important resource conservation and solid waste management option. Source reduction, often called “waste prevention” is defined as “activities to lessen the volume of material in products and packaging before that material enters the municipal solid waste management system.”