This is designed to lend a greater understanding concerning how plastics are produced, the different types of plastic along with their numerous properties and applications.
A plastic the type of synthetic or man-made polymer; similar in many ways to natural resins present in trees and also other plants. Webster’s Dictionary defines polymers as: some of various complex organic compounds manufactured by polymerization, competent at being molded, extruded, cast into various shapes and films, or drawn into filaments and then used as textile fibers.
A Little Bit HistoryThe reputation of manufactured plastics goes back over a hundred years; however, when compared with other materials, plastics are relatively modern. Their usage in the last century has allowed society to make huge technological advances. Although plastics are looked at as a contemporary invention, there have always been “natural polymers” including 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 example, 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 the uk. This product-that was dubbed Parkesine, now called celluloid-was an organic material produced by cellulose that when heated could be molded but retained its shape when cooled. Parkes claimed that it new material could a single thing that rubber was capable of, yet on the cheap. He had discovered a material which can be transparent in addition to carved into a large number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to make a synthetic varnish, came across the formula for a new synthetic polymer originating from coal tar. He subsequently named the new substance “Bakelite.” Bakelite, once formed, could not melted. Due to the properties as being an electrical insulator, Bakelite was utilized in the production of high-tech objects including cameras and telephones. It had been also utilized in the creation of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” because the term to illustrate this completely new class of materials.
The initial patent for pvc granule, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane was discovered during this time.
Plastics did not really remove until following the First World War, with the use 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 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. More would follow and through the 1960s, plastics were within everyone’s reach because of the inexpensive cost. Plastics had thus come to be considered ‘common’-an expression of your consumer society.
Because the 1970s, we have witnessed the advent of ‘high-tech’ plastics employed in demanding fields like health insurance and technology. New types and types of plastics with new or improved performance characteristics continue being developed.
From daily tasks to our most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs at all levels. Plastics are utilized such an array of applications because they are uniquely capable of offering a variety of properties that provide consumer benefits unsurpassed by other materials. Also, they are unique because their properties could be customized for every single individual end use application.
Oil and gas are definitely the major raw materials accustomed to manufacture plastics. The plastics production process often begins by treating parts of crude oil or gas in the “cracking process.” This process leads to the conversion of those components into hydrocarbon monomers such as ethylene and propylene. Further processing results in a wider range of monomers including styrene, soft pvc granule, ethylene glycol, terephthalic acid and others. These monomers are then chemically bonded into chains called polymers. The numerous mixtures of monomers yield plastics with a variety of properties and characteristics.
PlasticsMany common plastics are made of hydrocarbon monomers. These plastics are manufactured by linking many monomers together into long chains to make a polymer backbone. Polyethylene, polypropylene and polystyrene are the most common examples of these. Below is actually a diagram of polyethylene, the most basic plastic structure.
Although the basic makeup of many plastics is carbon and hydrogen, other elements may also be involved. Oxygen, chlorine, fluorine and nitrogen may also be 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 created it might be heated and reformed repeatedly. Celluloid is actually a thermoplastic. This property allows for easy processing and facilitates recycling. Another group, the thermosets, can not be remelted. Once these plastics are formed, reheating may cause the material to decompose instead of melt. Bakelite, poly phenol formaldehyde, can be a thermoset.
Each plastic has very distinct characteristics, but a majority of plastics get the following general attributes.
Plastics can be extremely resistant to chemicals. Consider each of the cleaning fluids in your house which can be packaged in plastic. The warning labels describing what occurs if the chemical enters into connection with 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 may be both thermal and electrical insulators. A stroll via your house will reinforce this idea. Consider every one of the electrical appliances, cords, outlets and wiring that happen to be 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 is made of polypropylene as well as the fiberfill in several winter jackets is acrylic or polyester.
Generally, plastics are extremely lightweight with varying degrees of strength. Consider the plethora 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 although some sink. But, when compared to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics may be processed in various methods to produce thin fibers or very intricate parts. Plastics can be molded into bottles or parts of cars, such as dashboards and fenders. Some pvcppellet stretch and so are very flexible. Other plastics, like polyethylene, polystyrene (Styrofoam™) and polyurethane, may be foamed. Plastics might be molded into drums or even be combined with solvents to get adhesives or paints. Elastomers plus some plastics stretch and therefore are very flexible.
Polymers are materials using a seemingly limitless range of characteristics and colors. Polymers have many inherent properties that can be further enhanced by an array of additives to broaden their uses and applications. Polymers can be created to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers 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 generate many kinds of items with application in lots of major markets.
Polymers are generally manufactured from petroleum, although not always. Many polymers are made of repeat units produced by natural gas or coal or crude oil. But building block repeat units can sometimes be produced from renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have been created from renewable materials for example cellulose acetate employed for screwdriver handles and gift ribbon. As soon as the building blocks can be done 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 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 employed to protect plastics in the degrading negative effects of light, heat, or bacteria; to change such plastic properties, such as melt flow; to offer color; to supply foamed structure; to offer flame retardancy; and to provide special characteristics such as improved surface appearance or reduced tack/friction.
Plasticizers are materials integrated into certain plastics to enhance flexibility and workability. Plasticizers are located in several plastic film wraps as well as in flexible plastic tubing, each of which are commonly employed 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 make sure that these materials are safe.
Processing MethodsThere are several different processing methods utilized to make plastic products. Here are the 4 main methods where plastics are processed to produce the items that consumers use, such as plastic film, bottles, bags and also other containers.
Extrusion-Plastic pellets or granules are first loaded in 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 combination of heat from the mechanical work done and also the new sidewall metal. At the end of the extruder, the molten plastic needs out by way of a small opening or die to shape the finished product. Because the plastic product extrudes from your die, it really is cooled by air or water. Plastic films and bags are created by extrusion processing.
Injection molding-Injection molding, plastic pellets or granules are fed from a hopper into a heating chamber. An extrusion screw pushes the plastic with the heating chamber, where material is softened in to 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. Once the plastic cools to some solid state, the mold opens along with the finished part is ejected. This process is utilized to help make products for example butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is actually a process used together with extrusion or injection molding. In one form, extrusion blow molding, the die forms a continuous semi-molten tube of thermoplastic material. A chilled mold is clamped round the tube and compressed air will be blown in to the tube to conform the tube towards the interior from the mold and also to solidify the stretched tube. Overall, the target is to make a uniform melt, form it in a tube with the desired cross section and blow it into the exact shape of the item. This procedure is utilized to produce hollow plastic products and its particular principal advantage is its ability to produce hollow shapes while not having to join a couple of separately injection molded parts. This procedure can be used to make items for example commercial drums and milk bottles. Another blow molding approach 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 into the final shape in a chilled mold. This is basically the process to help make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes a closed mold mounted on a device capable of rotation on two axes simultaneously. Plastic granules are put inside the mold, which can be then heated within an oven to melt the plastic Rotation around both axes distributes the molten plastic in a uniform coating within the mold till the part is set by cooling. This process is used to produce hollow products, for example large toys or kayaks.
Durables vs. Non-DurablesAll types of plastic items are classified throughout the plastic industry as being either a durable or non-durable plastic good. These classifications are used to talk about a product’s expected life.
Products by using a useful lifetime of 3 years or even more are called durables. They include appliances, furniture, electronic products, automobiles, and building and construction materials.
Products having a useful life of under three 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 clear, tough and has good gas and moisture barrier properties so that it is well suited for carbonated beverage applications as well as other food containers. The reality that it provides high use temperature allows it to be employed in applications for example heatable pre-prepared food trays. Its heat resistance and microwave transparency make it an excellent heatable film. Furthermore, 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 since it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all kinds of polyethylene, is restricted to people food packaging applications that do not require an oxygen or CO2 barrier. In film form, HDPE is 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 used for packaging many household and also industrial chemicals like detergents, bleach and acids. General uses of HDPE include injection-molded beverage cases, bread trays along with 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 up into rigid and flexible 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 may be caused by its potential to deal with 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 found in film applications due to the toughness, flexibility and transparency. LDPE has a low melting point which makes it popular for usage in applications where heat sealing is needed. Typically, LDPE is used to manufacture flexible films such as those useful for dry cleaned garment bags and create bags. LDPE can also be utilized 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 also popular in packaging. It comes with a high melting point, making it perfect for hot fill liquids. Polypropylene is found 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 resistance to water and also to 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 actually a versatile plastic which can be rigid or foamed. General purpose polystyrene is clear, hard and brittle. Its clarity allows it to be used when transparency is vital, like medical and food packaging, in laboratory ware, and in certain electronic uses. Expandable Polystyrene (EPS) is commonly extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers like egg crates. EPS is also directly formed into cups and tubs for dry foods like dehydrated soups. Both foamed sheet and molded tubs are utilized extensively in take-out restaurants for their lightweight, stiffness and excellent thermal insulation.
If you are mindful of it or otherwise not, plastics play an essential part in your own life. Plastics’ versatility permit them to be employed in everything from car parts to doll parts, from soft drink bottles to the refrigerators they are saved in. From your car you drive to operate in to the television you watch in your own home, plastics make your life easier and much better. So how is it that plastics are becoming so commonly used? How did plastics get to be the material of choice for numerous varied applications?
The simple fact is that plastics provides those things consumers want and need at economical costs. Plastics hold the unique ability to be manufactured in order to meet very specific functional needs for consumers. So maybe there’s another question that’s relevant: What do I want? Irrespective of how you answer this query, plastics often will match your needs.
In case a product is constructed of plastic, there’s grounds. And odds are the reason why has everything related to helping you, the buyer, get what you need: Health. Safety. Performance. and Value. Plastics Have The Ability.
Just consider the changes we’ve found in the food market lately: plastic wrap helps keep meat fresh while protecting it through the poking and prodding fingers of your respective fellow shoppers; plastic containers mean you could lift an economy-size bottle of juice and really should 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 several of the big-ticket items you buy. Plastics help to make portable phones and computers that basically are portable. They assist major appliances-like refrigerators or dishwashers-resist corrosion, go longer and operate better. Plastic car fenders and body panels resist dings, so that you can cruise the supermarket parking lot with confidence.
Modern packaging-for example heat-sealed plastic pouches and wraps-helps keep food fresh and free of contamination. This means the resources that went into producing that food aren’t wasted. It’s the exact same thing as soon as you get the food home: plastic wraps and resealable containers make your leftovers protected-much to the chagrin of kids everywhere. Actually, packaging experts have estimated that each pound of plastic packaging can reduce food waste by around 1.7 pounds.
Plastics can also help you bring home more product with less packaging. For instance, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of a beverage including juice, soda or water. You’d need 3 pounds of aluminum to give home the equivalent amount of product, 8 pounds of steel or higher 40 pounds of glass. Not only do plastic bags require less total energy to make than paper bags, they conserve fuel in shipping. It takes seven trucks to hold the identical quantity of paper bags as suits one truckload of plastic bags. Plastics make packaging more potent, which ultimately conserves resources.
LightweightingPlastics engineers will always be endeavoring to do a lot 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 over 180 million pounds of packaging in 2006 only for 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone a comparable reduction, weighing 30 percent below exactly what it did 2 decades ago.
Doing more with less helps conserve resources in another way. It helps save energy. In fact, plastics can play a substantial role in energy conservation. Just consider the decision you’re asked to make with 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 generate than paper bags, they conserve fuel in shipping. It takes seven trucks to transport the same variety of paper bags as suits one truckload of plastic bags.
Plastics also aid to conserve energy at home. Vinyl siding and windows help cut energy consumption and lower heating and air conditioning bills. Furthermore, the U.S. Department of Energy estimates that utilize of plastic foam insulation in homes and buildings annually could save over 60 million barrels of oil over other sorts of insulation.
The identical principles apply in appliances including refrigerators and air conditioners. Plastic parts and insulation have helped to boost their energy efficiency by 30 to 50 percent since the early 1970s. Again, this energy savings helps in reducing your cooling and heating 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 regular source of returned PETE bottles. With adding HDPE milk jug recycling in the late 1980s, plastics recycling has grown steadily but relative to competing packaging materials.
Roughly 60 % from the United states population-about 148 million people-have accessibility to a plastics recycling program. The two common types of collection are: curbside collection-where consumers place designated plastics within a special bin being found by a public or private hauling company (approximately 8,550 communities participate in curbside recycling) and drop-off centers-where consumers place their recyclables into a centrally located facility (12,000). Most curbside programs collect multiple type of plastic resin; usually both PETE and HDPE. Once collected, the plastics are sent to a material recovery facility (MRF) or handler for sorting into single resin streams to enhance product value. The sorted plastics are then baled to minimize shipping costs to reclaimers.
Reclamation is the next phase where the plastics are chopped into flakes, washed to remove contaminants and sold to finish users to manufacture new services like bottles, containers, clothing, carpet, clear pvc granule, etc. The number of companies handling and reclaiming post-consumer plastics today has finished 5 times greater than in 1986, growing from 310 companies to 1,677 in 1999. The number of end uses for recycled plastics is growing. The government and state government along with many major corporations now support market growth through purchasing preference policies.
At the outset of the 1990s, concern across the perceived lowering of landfill capacity spurred efforts by legislators to mandate the usage of recycled materials. Mandates, as a method of expanding markets, could be troubling. Mandates may neglect to take health, safety and gratification attributes into mind. Mandates distort the economic decisions and can result in sub optimal financial results. Moreover, they are unable to acknowledge the lifespan cycle great things about alternatives to the surroundings, like the efficient usage of energy and natural resources.
Pyrolysis involves heating plastics inside the absence or near absence of oxygen to interrupt on the long polymer chains into small molecules. Under mild conditions polyolefins can yield a petroleum-like oil. Special conditions can yield monomers including ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and deadly carbon monoxide are known as synthesis gas, or syngas). Contrary to pyrolysis, combustion is undoubtedly an oxidative method that generates heat, co2, and water.
Chemical recycling is actually a special case where condensation polymers like PET or nylon are chemically reacted to form starting materials.
Source ReductionSource reduction is gaining more attention being an important resource conservation and solid waste management option. Source reduction, often called “waste prevention” is defined as “activities to lower the volume of material in products and packaging before that material enters the municipal solid waste management system.”