This was created to lend a greater understanding concerning how plastics are produced, the several types of plastic in addition to their numerous properties and applications.
A plastic is a kind of synthetic or man-made polymer; similar in many ways to natural resins present in trees along with other plants. Webster’s Dictionary defines polymers as: any one of various complex organic compounds made by polymerization, competent at being molded, extruded, cast into various shapes and films, or drawn into filaments then used as textile fibers.
A Little Bit HistoryThe past of manufactured plastics dates back over 100 years; however, in comparison to other materials, plastics are relatively modern. Their usage during the last century has allowed society to produce huge technological advances. Although plastics are thought of as a contemporary invention, there have always been “natural polymers” like 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 applied. By way of example, prior to the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes utilized to replace glass.
Alexander Parkes unveiled the initial man-made plastic at the 1862 Great International Exhibition in London. This material-which was dubbed Parkesine, now called celluloid-was an organic material based on cellulose that after heated may be molded but retained its shape when cooled. Parkes claimed that this new material could do anything whatsoever that rubber was capable of, yet at a lower price. He had discovered a material which can be transparent and also carved into a huge number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to produce 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 be melted. Due to its properties as being an electrical insulator, Bakelite was utilized in the creation of high-tech objects including cameras and telephones. It had been also used in the production of ashtrays and as a substitute for jade, marble and amber. By 1909, Baekland had coined “plastics” since the term to illustrate this completely new type of materials.
The initial patent for pvc compound, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane was also discovered during this period.
Plastics failed to really explode until right after the First World War, by using petroleum, a substance much easier to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal during the hardship times during World War’s I & II. After World War 2, newer plastics, for example polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. A lot more would follow and through the 1960s, plastics were within everyone’s reach due to their inexpensive cost. Plastics had thus come that need considering ‘common’-an expression from the consumer society.
Ever since the 1970s, we have witnessed the arrival of ‘high-tech’ plastics found in demanding fields like health and technology. New types and forms of plastics with new or improved performance characteristics continue being developed.
From daily tasks to our own most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs whatsoever levels. Plastics are used in such an array of applications since they are uniquely able to offering a variety of properties offering consumer benefits unsurpassed by many other materials. Also, they are unique in that their properties could be customized for each individual end use application.
Oil and gas are the major raw materials used to manufacture plastics. The plastics production process often begins by treating components of oil or natural gas in the “cracking process.” This method brings about the conversion of the components into hydrocarbon monomers including ethylene and propylene. Further processing leads to a wider variety of monomers such as styrene, upvc compound, ethylene glycol, terephthalic acid and many more. These monomers are then chemically bonded into chains called polymers. The numerous mixtures of monomers yield plastics with a wide range of properties and characteristics.
PlasticsMany common plastics are manufactured from hydrocarbon monomers. These plastics are manufactured by linking many monomers together into long chains to create a polymer backbone. Polyethylene, polypropylene and polystyrene are the most typical samples of these. Below can be a diagram of polyethylene, the most basic plastic structure.
Although the basic makeup of several plastics is carbon and hydrogen, other elements can be involved. Oxygen, chlorine, fluorine and nitrogen can also be 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 vast majority of plastics are thermoplastic, which means when the plastic is formed it might be heated and reformed repeatedly. Celluloid is a thermoplastic. This property permits easy processing and facilitates recycling. One other group, the thermosets, can not be remelted. Once these plastics are formed, reheating can cause the information to decompose as opposed to melt. Bakelite, poly phenol formaldehyde, can be a thermoset.
Each plastic has very distinct characteristics, but many plastics possess the following general attributes.
Plastics can be quite immune to chemicals. Consider all of the cleaning fluids in your home that are packaged in plastic. The warning labels describing what will happen as soon as the chemical makes connection with skin or eyes or is 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 each of the electrical appliances, cords, outlets and wiring that are 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 lots of skiers wear is made of polypropylene and the fiberfill in lots of winter jackets is acrylic or polyester.
Generally, plastics are incredibly light in weight with varying degrees of strength. Consider the plethora of applications, from toys to the frame structure of space stations, or from delicate nylon fiber in pantyhose to Kevlar®, which is often used in bulletproof vests. Some polymers float in water while others sink. But, when compared to density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics could be processed in different approaches to produce thin fibers or very intricate parts. Plastics could be molded into bottles or parts of cars, like dashboards and fenders. Some pvcppellet stretch and therefore are very flexible. Other plastics, for example polyethylene, polystyrene (Styrofoam™) and polyurethane, may be foamed. Plastics could be molded into drums or perhaps be blended with solvents to get adhesives or paints. Elastomers and some plastics stretch and are very flexible.
Polymers are materials having a seemingly limitless selection of characteristics and colors. Polymers have numerous inherent properties that could be further enhanced by a variety 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 may also make possible products that do not readily range from natural world, like clear sheets, foamed insulation board, and versatile films. Plastics can be molded or formed to produce many different types of products with application in numerous major markets.
Polymers are often created from petroleum, yet not always. Many polymers are created from repeat units derived from natural gas or coal or crude oil. But foundation repeat units can occasionally be created from renewable materials such as polylactic acid from corn or cellulosics from cotton linters. Some plastics have always been made out of renewable materials like cellulose acetate employed for screwdriver handles and gift ribbon. Once the foundations can be done more economically from renewable materials than from non-renewable fuels, either old plastics find new raw materials or new plastics are introduced.
Many plastics are blended with additives as they are processed into finished products. The additives are included in plastics to alter and improve their basic mechanical, physical, or chemical properties. Additives are used to protect plastics from your degrading negative effects of light, heat, or bacteria; to alter such plastic properties, such as melt flow; to deliver color; to deliver foamed structure; to deliver flame retardancy; as well as to provide special characteristics for example improved surface appearance or reduced tack/friction.
Plasticizers are materials integrated into certain plastics to enhance flexibility and workability. Plasticizers are found in numerous plastic film wraps and then in flexible plastic tubing, each of which are generally employed in food packaging or processing. All plastics employed in food contact, such as the additives and plasticizers, are regulated by the United states Food and Drug Administration (FDA) to make certain that these materials are secure.
Processing MethodsThere are some different processing methods used to make plastic products. Below are the 4 main methods through which plastics are processed to make the items that consumers use, for example plastic film, bottles, bags and also 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, through which it is actually moved by the action of a continuously revolving screw. The plastic is melted by a variety of heat from your mechanical work done and also the sidewall metal. At the conclusion of the extruder, the molten plastic needs out through a small opening or die to shape the finished product. As the plastic product extrudes through 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 from the hopper into a heating chamber. An extrusion screw pushes the plastic through the heating chamber, the location where the material is softened in a fluid state. Again, mechanical work and hot sidewalls melt the plastic. At the end of this chamber, the resin is forced at high pressure into a cooled, closed mold. Once the plastic cools into a solid state, the mold opens along with the finished part is ejected. This technique is commonly used to help make products like butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is a process used jointly with extrusion or injection molding. In a 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 is going to be blown in to the tube to conform the tube to the interior of the mold as well as solidify the stretched tube. Overall, the goal is to generate a uniform melt, form it in to a tube together with the desired cross section and blow it into the exact model of the product. This process is commonly used to manufacture hollow plastic products and its principal advantage is being able to produce hollow shapes without needing to join two or more separately injection molded parts. This method is utilized to make items such as commercial drums and milk bottles. Another blow molding strategy is to injection mold an intermediate shape termed as a preform after which to heat the preform and blow the warmth-softened plastic into the final shape within a chilled mold. Here is the process to create carbonated soft drink bottles.
Rotational Molding-Rotational molding is made up of closed mold placed on a unit competent at rotation on two axes simultaneously. Plastic granules are put from the mold, which is then heated within an oven to melt the plastic Rotation around both axes distributes the molten plastic in a uniform coating on the inside of the mold before the part is set by cooling. This procedure is commonly used to make hollow products, for instance large toys or kayaks.
Durables vs. Non-DurablesAll forms of plastic goods are classified inside the plastic industry as being either a durable or non-durable plastic good. These classifications are used to make reference to a product’s expected life.
Products with a useful life of 3 years or higher are referred to as durables. They include appliances, furniture, electronic products, automobiles, and building and construction materials.
Products using a useful lifetime of less than three years are usually termed as non-durables. Common applications include packaging, trash bags, cups, eating utensils, sporting and recreational equipment, toys, medical devices and disposable diapers.
Polyethylene Terephthalate (PET or PETE) is apparent, tough and has good gas and moisture barrier properties rendering it well suited for carbonated beverage applications as well as other food containers. The reality that it has high use temperature allows it to be found in applications like heatable pre-prepared food trays. Its heat resistance and microwave transparency make it an excellent heatable film. In addition, it finds applications such diverse end uses as fibers for clothing and carpets, bottles, food containers, strapping, and engineering plastics for precision-molded parts.
High Density Polyethylene (HDPE) is utilized for several packaging applications mainly because it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all kinds of polyethylene, is restricted to individuals 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 also in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it can be utilized for packaging many household in addition to industrial chemicals including 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, long lasting stability, good weatherability and stable electrical properties. Vinyl products might be broadly divided 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 might be attributed to its resistance to 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 used in film applications due to the toughness, flexibility and transparency. LDPE carries a low melting point rendering it popular to use in applications where heat sealing is important. Typically, LDPE is used to manufacture flexible films for example those used for dry cleaned garment bags and produce bags. LDPE can also be utilized to manufacture some flexible lids and bottles, and it is widely used in wire and cable applications for its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and is commonly used in packaging. It features a high melting point, which makes it suitable for hot fill liquids. Polypropylene is located in from flexible and rigid packaging to fibers for fabrics and carpets and enormous molded parts for automotive and consumer products. Like other plastics, polypropylene has excellent effectiveness against water and 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 apparent, hard and brittle. Its clarity allows so that it is used when transparency is very important, like medical and food packaging, in laboratory ware, and also in certain electronic uses. Expandable Polystyrene (EPS) is commonly extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers such as 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 employed extensively in take-out restaurants for their lightweight, stiffness and excellent thermal insulation.
If you are mindful of it or perhaps not, plastics play a crucial part in your daily life. Plastics’ versatility let them be used in from car parts to doll parts, from soft drink bottles towards the refrigerators they may be saved in. From the car you drive to operate in to the television you watch in your house, plastics make your life easier and. Just how is it that plastics are becoming so popular? How did plastics get to be the material of choice for numerous varied applications?
The straightforward response is that plastics provides the things consumers want and desire at economical costs. Plastics get the unique ability to be manufactured to fulfill very specific functional needs for consumers. So maybe there’s another question that’s relevant: Exactly what do I want? Irrespective of how you answer this query, plastics can probably satisfy your needs.
When a product is made of plastic, there’s reasons. And chances are the reason why has everything concerning helping you to, the buyer, get what you need: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just think about the changes we’ve observed in the supermarket in recent years: plastic wrap assists in keeping meat fresh while protecting it from 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 can be shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also help you to get maximum value from several of the big-ticket stuff you buy. Plastics help make portable phones and computers that really are portable. They help major appliances-like refrigerators or dishwashers-resist corrosion, stay longer and operate more effectively. Plastic car fenders and the body panels resist dings, so you can cruise the supermarket parking lot with confidence.
Modern packaging-for example heat-sealed plastic pouches and wraps-assists in keeping food fresh and without any contamination. Which means the resources that went into producing that food aren’t wasted. It’s the exact same thing once you receive the food home: plastic wraps and resealable containers keep your leftovers protected-much to the chagrin of kids everywhere. In reality, packaging experts have estimated that each pound of plastic packaging is effective in reducing 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 your beverage like juice, soda or water. You’d need 3 pounds of aluminum to give home the equivalent amount of product, 8 pounds of steel or over 40 pounds of glass. In addition plastic bags require less total energy to make than paper bags, they conserve fuel in shipping. It requires seven trucks to transport the same amount of paper bags as suits one truckload of plastic bags. Plastics make packaging better, which ultimately conserves resources.
LightweightingPlastics engineers will almost always be working to do much more with less material. Since 1977, the two-liter plastic soft drink bottle went from weighing 68 grams just to 47 grams today, representing a 31 percent reduction per bottle. That saved over 180 million pounds of packaging in 2006 just for 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone the same reduction, weighing 30 percent lower than just what it did 20 years ago.
Doing more with less helps conserve resources in yet another way. It will help save energy. The truth is, plastics can enjoy an important role in energy conservation. Just look at the decision you’re asked to make at 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 make than paper bags, they conserve fuel in shipping. It will require seven trucks to transport exactly the same amount of paper bags as fits in one truckload of plastic bags.
Plastics also assist to conserve energy in your house. Vinyl siding and windows help cut energy consumption and lower cooling and heating bills. Furthermore, the Usa Department of Energy estimates that utilize of plastic foam insulation in homes and buildings each year could save over 60 million barrels of oil over other sorts of insulation.
A similar principles apply in appliances for example refrigerators and ac units. Plastic parts and insulation have helped to enhance their energy efficiency by 30 to one half since the early 1970s. Again, this energy savings helps in reducing 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 in the early 1980s because of state level bottle deposit programs, which produced a regular flow of returned PETE bottles. With incorporating HDPE milk jug recycling from the late 1980s, plastics recycling has expanded steadily but in accordance with competing packaging materials.
Roughly 60 % of the United states population-about 148 million people-have access to a plastics recycling program. The two common forms of collection are: curbside collection-where consumers place designated plastics inside a special bin to get acquired by way of a public or private hauling company (approximately 8,550 communities get involved in curbside recycling) and drop-off centers-where consumers take their recyclables into a centrally located facility (12,000). Most curbside programs collect several sort of plastic resin; usually both PETE and HDPE. Once collected, the plastics are shipped 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 lessen shipping costs to reclaimers.
Reclamation is the next phase in which the plastics are chopped into flakes, washed to get rid of contaminants and sold to finish users to manufacture new releases like bottles, containers, clothing, carpet, pvc compound, etc. The number of companies handling and reclaiming post-consumer plastics today is over five times higher than in 1986, growing from 310 companies to 1,677 in 1999. The amount of end uses for recycled plastics keeps growing. The government and state government along with many major corporations now support market growth through purchasing preference policies.
At the beginning of the 1990s, concern across the perceived lowering of landfill capacity spurred efforts by legislators to mandate the application of recycled materials. Mandates, as a method of expanding markets, can be troubling. Mandates may forget to take health, safety and performance attributes into account. Mandates distort the economic decisions and can cause sub optimal financial results. Moreover, they are not able to acknowledge the life cycle advantages of alternatives to the surroundings, for example the efficient usage of energy and natural resources.
Pyrolysis involves heating plastics inside the absence or near deficiency of oxygen to interrupt 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 called synthesis gas, or syngas). In contrast to pyrolysis, combustion is definitely an oxidative procedure that generates heat, carbon dioxide, and water.
Chemical recycling can be a special case where condensation polymers like PET or nylon are chemically reacted to produce 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 identified as “activities to lessen the level of material in products and packaging before that material enters the municipal solid waste management system.”