This was created to lend a greater understanding concerning how plastics are produced, the various kinds of plastic as well as 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 as well as other plants. Webster’s Dictionary defines polymers as: any one of various complex organic compounds manufactured by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments after which used as textile fibers.
A Little HistoryThe reputation of manufactured plastics dates back greater than 100 years; however, in comparison with other materials, plastics are relatively modern. Their usage in the last century has enabled society to help make huge technological advances. Although plastics are considered to be 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 just like the way manufactured plastics are now applied. For example, prior to the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes employed to replace glass.
Alexander Parkes unveiled the initial man-made plastic on the 1862 Great International Exhibition in London. This material-that has been dubbed Parkesine, now called celluloid-was an organic material based on cellulose that when heated could be molded but retained its shape when cooled. Parkes claimed this new material could do anything whatsoever that rubber was capable of, yet for less money. He had discovered a material that may be transparent as well as carved into a huge number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to generate a synthetic varnish, came across the formula for a new synthetic polymer caused by coal tar. He subsequently named the brand new substance “Bakelite.” Bakelite, once formed, could not really melted. Due to the properties for an electrical insulator, Bakelite was applied in the production of high-tech objects including cameras and telephones. It absolutely was also utilized in the production of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” since the term to clarify 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 had also been discovered during this period.
Plastics did not really remove until once the First World War, with the use of petroleum, a substance quicker 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, like polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. A lot more would follow and also by the 1960s, plastics were within everyone’s reach because of the inexpensive cost. Plastics had thus come that need considering ‘common’-a symbol in the consumer society.
Since the 1970s, we certainly have witnessed the advent of ‘high-tech’ plastics employed in demanding fields including health insurance and technology. New types and kinds 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 employed in such a wide array of applications since they are uniquely capable of offering a variety of properties that supply consumer benefits unsurpassed by many other materials. They are also unique for the reason that their properties might be customized for every individual end use application.
Oil and natural gas are definitely the major raw materials accustomed to manufacture plastics. The plastics production process often begins by treating aspects of oil or gas in a “cracking process.” This procedure leads to the conversion of those components into hydrocarbon monomers such as ethylene and propylene. Further processing results in a wider range of monomers for example 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 made from hydrocarbon monomers. These plastics are made by linking many monomers together into long chains to form a polymer backbone. Polyethylene, polypropylene and polystyrene are the most common instances of these. Below is a diagram of polyethylene, the easiest plastic structure.
However the basic makeup of several plastics is carbon and hydrogen, other elements may also be involved. Oxygen, chlorine, fluorine and nitrogen will also be found in the molecular makeup of countless 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, which means when the plastic is created it can be heated and reformed repeatedly. Celluloid is actually a thermoplastic. This property permits easy processing and facilitates recycling. Another group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating will cause the material to decompose rather than melt. Bakelite, poly phenol formaldehyde, can be a thermoset.
Each plastic has very distinct characteristics, but many plastics get the following general attributes.
Plastics can be extremely resistant to chemicals. Consider all the cleaning fluids at your residence that are packaged in plastic. The warning labels describing what happens if the chemical comes into connection with skin or eyes or perhaps is ingested, emphasizes the chemical resistance of these 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 through your house will reinforce this idea. Consider all 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 lots of skiers wear consists of polypropylene and the fiberfill in lots of winter jackets is acrylic or polyester.
Generally, plastics are really light in weight with varying levels of strength. Consider the range of applications, from toys to 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 while some sink. But, in comparison to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics can be processed in different ways to produce thin fibers or very intricate parts. Plastics might be molded into bottles or aspects of cars, such as dashboards and fenders. Some pvcppellet stretch and they are very flexible. Other plastics, such as polyethylene, polystyrene (Styrofoam™) and polyurethane, could be foamed. Plastics can be molded into drums or be combined with solvents to become adhesives or paints. Elastomers and some plastics stretch and so are very flexible.
Polymers are materials having a seemingly limitless array of characteristics and colors. Polymers have lots of 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 also can make possible products that do not readily come from the natural world, like clear sheets, foamed insulation board, and flexible films. Plastics might be molded or formed to make many different types of products with application in several major markets.
Polymers are generally made from petroleum, although not always. Many polymers are made of repeat units produced from natural gas or coal or crude oil. But foundation repeat units can often be produced from renewable materials such as polylactic acid from corn or cellulosics from cotton linters. Some plastics have invariably been created from renewable materials such as cellulose acetate useful for screwdriver handles and gift ribbon. If the building blocks can be created 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 since they are processed into finished products. The additives are included in plastics to alter and boost their basic mechanical, physical, or chemical properties. Additives are used to protect plastics in the degrading effects of light, heat, or bacteria; to change such plastic properties, including melt flow; to supply color; to provide foamed structure; to provide flame retardancy; as well as to provide special characteristics for example improved surface appearance or reduced tack/friction.
Plasticizers are materials incorporated into certain plastics to improve flexibility and workability. Plasticizers are found in numerous plastic film wraps and in flexible plastic tubing, both of which are typically utilized in food packaging or processing. All plastics employed in food contact, such as the additives and plasticizers, are regulated through the Usa Food and Drug Administration (FDA) to make certain that these materials are safe.
Processing MethodsThere are some different processing methods accustomed to make plastic products. Listed below are the four main methods by which plastics are processed to form the products that consumers use, for example plastic film, bottles, bags and also other containers.
Extrusion-Plastic pellets or granules are first loaded right into a hopper, then fed into an extruder, which is a long heated chamber, whereby it can be 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 is forced out via a small opening or die to shape the finished product. Because the plastic product extrudes from your 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 in a heating chamber. An extrusion screw pushes the plastic with the heating chamber, where the material is softened in a fluid state. Again, mechanical work and hot sidewalls melt the plastic. At the conclusion of this chamber, the resin is forced at high-pressure right into a cooled, closed mold. When the plastic cools to your solid state, the mold opens and also the finished part is ejected. This method can be used to help make products for example butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is actually a process used in conjunction 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 throughout the tube and compressed air is going to be blown in to the tube to conform the tube on the interior of your mold and also to solidify the stretched tube. Overall, the target is to generate a uniform melt, form it in to a tube using the desired cross section and blow it in the exact form of this product. This technique is commonly used to produce hollow plastic products and its particular principal advantage is its ability to produce hollow shapes without having to join several separately injection molded parts. This technique can be used to create items like commercial drums and milk bottles. Another blow molding technique is to injection mold an intermediate shape termed as a preform after which to heat the preform and blow the heat-softened plastic to the final shape in the chilled mold. Here is the process to help make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes closed mold placed on a piece of equipment competent at rotation on two axes simultaneously. Plastic granules are placed within the mold, which 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 up until the part is defined by cooling. This process is used to create hollow products, by way of example large toys or kayaks.
Durables vs. Non-DurablesAll kinds of plastic goods are classified in the plastic industry as being either a durable or non-durable plastic good. These classifications are utilized to talk about a product’s expected life.
Products having a useful lifetime of 36 months or even more are called durables. They include appliances, furniture, electronic products, automobiles, and building and construction materials.
Products having a useful life of less than three years are generally known as non-durables. Common applications include packaging, trash bags, cups, eating utensils, sporting and recreational equipment, toys, medical devices and disposable diapers.
Polyethylene Terephthalate (PET or PETE) is apparent, tough and it has good gas and moisture barrier properties so that it is well suited for carbonated beverage applications as well as other food containers. The reality that it has high use temperature allows so that it is used in applications such as heatable pre-prepared food trays. Its heat resistance and microwave transparency help it become an excellent heatable film. It also finds applications in these 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 as it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all kinds of polyethylene, is restricted to individuals 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; as well as 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 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-term stability, good weatherability and stable electrical properties. Vinyl products might be broadly separated 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 could be related to its effectiveness against most chemicals, imperviousness to attack by bacteria or micro-organisms, corrosion resistance and strength. Flexible vinyl is commonly 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 found in film applications because of its toughness, flexibility and transparency. LDPE carries a low melting point rendering it popular for use in applications where heat sealing is essential. Typically, LDPE can be used to produce flexible films including those utilized for dry cleaned garment bags and produce bags. LDPE is likewise accustomed to manufacture some flexible lids and bottles, and it is widely used in wire and cable applications for the stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and is also frequently used in packaging. It possesses a high melting point, so that it is perfect for hot fill liquids. Polypropylene is located in anything 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 as well as 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 really a versatile plastic which can be rigid or foamed. General purpose polystyrene is obvious, hard and brittle. Its clarity allows it to be used when transparency is vital, like in medical and food packaging, in laboratory ware, and in certain electronic uses. Expandable Polystyrene (EPS) is normally extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers such as egg crates. EPS is additionally directly formed into cups and tubs for dry foods such as dehydrated soups. Both foamed sheet and molded tubs are employed extensively in take-out restaurants for their lightweight, stiffness and ideal thermal insulation.
If you are aware of it or otherwise not, plastics play a crucial part in your life. Plastics’ versatility allow them to be used in from car parts to doll parts, from soft drink bottles for the refrigerators they are stored in. From your car you drive to function in the television you watch in the home, plastics help make your life easier and better. So how would it be that plastics are getting to be so commonly used? How did plastics get to be the material preferred by numerous varied applications?
The basic fact is that plastics can provide those things consumers want and need at economical costs. Plastics have the unique capability to be manufactured in order to meet very specific functional needs for consumers. So maybe there’s another question that’s relevant: Exactly what do I want? No matter how you answer this, plastics can probably match your needs.
If your product is made of plastic, there’s reasons. And chances are the main reason has everything with regards to helping you to, the consumer, get what you need: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just think about the changes we’ve noticed in the food market in recent years: plastic wrap assists in keeping meat fresh while protecting it through the poking and prodding fingers of your own fellow shoppers; plastic bottles mean you could lift an economy-size bottle of juice and should you accidentally drop that bottle, it is actually shatter-resistant. In each case, plastics make your life easier, healthier and safer.
Plastics also assist you in getting maximum value from a number of the big-ticket stuff you buy. Plastics help to make portable phones and computers that basically are portable. They assist major appliances-like refrigerators or dishwashers-resist corrosion, last longer and operate more effectively. Plastic car fenders and body panels resist dings, so you can cruise the food store car park with confidence.
Modern packaging-such as heat-sealed plastic pouches and wraps-assists in keeping food fresh and clear of contamination. That means the resources that went into producing that food aren’t wasted. It’s the exact same thing when you receive the food home: plastic wraps and resealable containers make your leftovers protected-much towards the chagrin of kids everywhere. The truth is, packaging experts have estimated that every pound of plastic packaging can reduce food waste by as much as 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 your beverage such as juice, soda or water. You’d need 3 pounds of aluminum to create 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 generate than paper bags, they conserve fuel in shipping. It requires seven trucks to carry a similar variety of paper bags as fits in one truckload of plastic bags. Plastics make packaging better, which ultimately conserves resources.
LightweightingPlastics engineers will always be trying to do a lot more with less material. Since 1977, the 2-liter plastic soft drink bottle has gone from weighing 68 grams to merely 47 grams today, representing a 31 percent reduction per bottle. That saved greater than 180 million pounds of packaging in 2006 for only 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone the same reduction, weighing 30 percent lower than what it really did two decades ago.
Doing more with less helps conserve resources in one other way. It helps save energy. Actually, plastics may play a tremendous role in energy conservation. Just glance at the decision you’re motivated 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. 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 carry the identical variety of paper bags as suits one truckload of plastic bags.
Plastics also help to conserve energy in your home. Vinyl siding and windows help cut energy consumption and lower heating and air conditioning bills. Furthermore, the Usa Department of Energy estimates which use of plastic foam insulation in homes and buildings each year could save over 60 million barrels of oil over other kinds of insulation.
A similar principles apply in appliances like refrigerators and air conditioners. Plastic parts and insulation have helped to boost their energy efficiency by 30 to one half because the early 1970s. Again, this energy savings helps reduce your air conditioning bills. And appliances run more quietly than earlier designs that used many other materials.
Recycling of post-consumer plastics packaging began in early 1980s because of state level bottle deposit programs, which produced a regular flow of returned PETE bottles. With adding HDPE milk jug recycling from the late 1980s, plastics recycling has exploded steadily but relative to competing packaging materials.
Roughly 60 percent in the United states population-about 148 million people-have access to a plastics recycling program. The two common types of collection are: curbside collection-where consumers place designated plastics in a special bin to become acquired from a public or private hauling company (approximately 8,550 communities participate in curbside recycling) and drop-off centers-where consumers get their recyclables into a centrally located facility (12,000). Most curbside programs collect several form 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 improve product value. The sorted plastics are then baled to lessen shipping costs to reclaimers.
Reclamation is the next step the location where the plastics are chopped into flakes, washed to get rid of contaminants and sold to end users to produce new items including bottles, containers, clothing, carpet, clear pvc granule, etc. The number of companies handling and reclaiming post-consumer plastics today has finished five times greater than in 1986, growing from 310 companies to 1,677 in 1999. The quantity 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.
At the beginning of the 1990s, concern on the perceived lowering of landfill capacity spurred efforts by legislators to mandate using recycled materials. Mandates, as a technique of expanding markets, can be troubling. Mandates may neglect to take health, safety and gratifaction attributes into mind. Mandates distort the economic decisions and can result in sub optimal financial results. Moreover, they are unable to acknowledge the lifestyle cycle benefits associated with options to the planet, for example the efficient usage of energy and natural resources.
Pyrolysis involves heating plastics in the absence or near shortage of oxygen to destroy 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 called synthesis gas, or syngas). Unlike pyrolysis, combustion is an oxidative method that generates heat, co2, and water.
Chemical recycling is really 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, also known as “waste prevention” is described as “activities to minimize the quantity of material in products and packaging before that material enters the municipal solid waste management system.”