This was designed to lend an improved understanding concerning how plastics are made, the different types of plastic along with their numerous properties and applications.
A plastic is a kind of synthetic or man-made polymer; similar in several ways to natural resins seen in trees as well as other plants. Webster’s Dictionary defines polymers as: any kind of various complex organic compounds produced by polymerization, able to being molded, extruded, cast into various shapes and films, or drawn into filaments and then used as textile fibers.
Just A Little HistoryThe history of manufactured plastics goes back over a hundred years; however, when compared to other materials, plastics are relatively modern. Their usage during the last century has allowed society to produce huge technological advances. Although plastics are regarded as a modern invention, there have invariably been “natural polymers” including 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 presently applied. For example, ahead of the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes accustomed to replace glass.
Alexander Parkes unveiled the very first man-made plastic on the 1862 Great International Exhibition inside london. This product-which was dubbed Parkesine, now called celluloid-was an organic material derived from cellulose once 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 on the cheap. He had discovered a material that may be transparent along with carved into a large number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to produce a synthetic varnish, found the formula to get a new synthetic polymer originating from coal tar. He subsequently named the latest substance “Bakelite.” Bakelite, once formed, could not really melted. Due to its properties for an electrical insulator, Bakelite was utilized in the production of high-tech objects including cameras and telephones. It was actually also employed in the creation of ashtrays and as a substitute for jade, marble and amber. By 1909, Baekland had coined “plastics” since the term to explain this completely new class of materials.
The very first patent for pvc granule, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane had also been discovered during this time.
Plastics did not really pull off until once 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 in the hardship days of 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. Much more would follow and through the 1960s, plastics were within everyone’s reach because of their inexpensive cost. Plastics had thus come to be considered ‘common’-a symbol of your consumer society.
Since the 1970s, we have witnessed the advent of ‘high-tech’ plastics used in demanding fields like health and technology. New types and forms of plastics with new or improved performance characteristics continue to be developed.
From daily tasks to your most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs at all levels. Plastics are being used in such a variety of applications because they are uniquely capable of offering a number of properties offering consumer benefits unsurpassed by other materials. They are also unique in this their properties may be customized for every individual end use application.
Oil and natural gas are the major raw materials employed to manufacture plastics. The plastics production process often begins by treating parts of oil or natural gas inside a “cracking process.” This procedure results in the conversion of such 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 more. These monomers are then chemically bonded into chains called polymers. The many 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 frequent samples of these. Below is a diagram of polyethylene, the simplest plastic structure.
Although the basic makeup of numerous plastics is carbon and hydrogen, other elements can be involved. Oxygen, chlorine, fluorine and nitrogen will also be located 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 divided into two distinct groups: thermoplastics and thermosets. Nearly all plastics are thermoplastic, which means as soon as the plastic is actually created it might be heated and reformed repeatedly. Celluloid is really a thermoplastic. This property allows for easy processing and facilitates recycling. The other group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating can cause the fabric to decompose as opposed to melt. Bakelite, poly phenol formaldehyde, is actually a thermoset.
Each plastic has very distinct characteristics, but most plastics possess the following general attributes.
Plastics are often very proof against chemicals. Consider all of the cleaning fluids in your house that happen to be packaged in plastic. The warning labels describing what occurs as soon as the chemical comes into contact with skin or eyes or perhaps is 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 by your house will reinforce this idea. Consider all the electrical appliances, cords, outlets and wiring which can be made or covered with plastics. Thermal resistance is evident in the 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 is made of polypropylene as well as the fiberfill in lots of winter jackets is acrylic or polyester.
Generally, plastics are extremely light in weight with varying levels of strength. Consider all the different applications, from toys for 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, compared to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics could be processed in several methods 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 so are very flexible. Other plastics, for example polyethylene, polystyrene (Styrofoam™) and polyurethane, can be foamed. Plastics can be molded into drums or perhaps be together with solvents to become adhesives or paints. Elastomers plus some plastics stretch and therefore are very flexible.
Polymers are materials having a seemingly limitless range of characteristics and colours. 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 done to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers could also make possible products that do not readily come from the natural world, including clear sheets, foamed insulation board, and versatile films. Plastics can be molded or formed to make many different types of merchandise with application in lots of major markets.
Polymers are often made of petroleum, but not always. Many polymers are made from repeat units derived from gas or coal or crude oil. But building block repeat units can sometimes 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 including cellulose acetate employed for screwdriver handles and gift ribbon. When the building blocks can be made 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 since they are processed into finished products. The additives are incorporated into plastics to alter and boost their basic mechanical, physical, or chemical properties. Additives are employed to protect plastics from the degrading negative effects of light, heat, or bacteria; to alter such plastic properties, for example melt flow; to supply color; to deliver foamed structure; to offer flame retardancy; as well as provide special characteristics for example improved surface appearance or reduced tack/friction.
Plasticizers are materials included in certain plastics to enhance flexibility and workability. Plasticizers can be found in several plastic film wraps and in flexible plastic tubing, each of which are normally utilized in food packaging or processing. All plastics used in food contact, like the additives and plasticizers, are regulated by the Usa Food and Drug Administration (FDA) to ensure these materials are safe.
Processing MethodsThere are a couple of different processing methods accustomed to make plastic products. Here are the 4 main methods through which plastics are processed to make the merchandise that consumers use, like 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, and that is a long heated chamber, whereby it is moved by the act of a continuously revolving screw. The plastic is melted by a combination of heat through the mechanical work done and through the new sidewall metal. At the conclusion of the extruder, the molten plastic needs out via a small opening or die to shape the finished product. Since the plastic product extrudes through the die, it is cooled by air or water. Plastic films and bags are made by extrusion processing.
Injection molding-Injection molding, plastic pellets or granules are fed coming from a hopper in to a heating chamber. An extrusion screw pushes the plastic through the heating chamber, in which the material is softened into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. After this chamber, the resin is forced at high pressure in 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 method is utilized to create products such as butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is a process used in conjunction 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 throughout the tube and compressed air is then blown to the tube to conform the tube for the interior of your mold and to solidify the stretched tube. Overall, the aim is to generate a uniform melt, form it in a tube together with the desired cross section and blow it in the exact model of the merchandise. This procedure is used to produce hollow plastic products as well as its principal advantage is being able to produce hollow shapes without having to join a couple of separately injection molded parts. This technique is used to help make items like commercial drums and milk bottles. Another blow molding approach is to injection mold an intermediate shape called a preform after which to heat the preform and blow the heat-softened plastic into the final shape in a chilled mold. This is the process to make carbonated soft drink bottles.
Rotational Molding-Rotational molding consists of a closed mold placed on a device capable of rotation on two axes simultaneously. Plastic granules are placed in the mold, which happens to be then heated in a oven to melt the plastic Rotation around both axes distributes the molten plastic in a uniform coating within the mold before the part is placed by cooling. This process is used to create hollow products, by way of example large toys or kayaks.
Durables vs. Non-DurablesAll varieties of plastic goods are classified in the plastic industry to be either a durable or non-durable plastic good. These classifications are widely used to refer to a product’s expected life.
Products by using a useful lifetime of three years or maybe more are termed as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products using a useful lifetime of lower than 36 months 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 apparent, tough and possesses good gas and moisture barrier properties rendering it well suited for carbonated beverage applications along with other food containers. The truth that it offers high use temperature allows that it is employed in applications like heatable pre-prepared food trays. Its heat resistance and microwave transparency allow it to be a perfect heatable film. It also 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 commonly used for most packaging applications as it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like a variety of polyethylene, has limitations to people food packaging applications which 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 also in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it really is employed for packaging many household along with industrial chemicals like 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 can be broadly separated into rigid and flexible materials. Rigid applications are concentrated in construction markets, consisting of pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings could be attributed to its potential to deal with 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 for its toughness, flexibility and transparency. LDPE includes a low melting point so that it is popular to be used in applications where heat sealing is necessary. Typically, LDPE is used to produce flexible films such as those employed for dry cleaned garment bags and create bags. LDPE is likewise employed to manufacture some flexible lids and bottles, in fact it is commonly used in wire and cable applications for the stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and it is popular in packaging. It has a high melting point, which makes it ideal for hot fill liquids. Polypropylene can be found in from flexible and rigid packaging to fibers for fabrics and carpets and large molded parts for automotive and consumer products. Like other plastics, polypropylene has excellent resistance to water and to salt and acid solutions that happen to 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 obvious, hard and brittle. Its clarity allows that it is used when transparency is vital, as with medical and food packaging, in laboratory ware, and in certain electronic uses. Expandable Polystyrene (EPS) is typically extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers for example egg crates. EPS is also directly formed into cups and tubs for dry foods for example 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 aware about it or perhaps not, plastics play an essential part in your own life. Plastics’ versatility permit them to be utilized in everything from car parts to doll parts, from soft drink bottles on the refrigerators these are kept in. From the car you drive to operate in the television you watch in your own home, plastics make your life easier and much better. Now how is it that plastics are getting to be so commonly used? How did plastics get to be the material of choice for numerous varied applications?
The easy answer is that plastics can offer the points consumers want and require at economical costs. Plastics hold the unique power to be manufactured to fulfill very specific functional needs for consumers. So maybe there’s another question that’s relevant: What exactly do I want? Regardless how you answer this question, plastics can probably suit your needs.
When a product consists of plastic, there’s a reason. And chances are the reason why has everything related to helping you to, the consumer, get what you wish: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just look at the changes we’ve found in the grocery store lately: plastic wrap helps keep meat fresh while protecting it from the poking and prodding fingers of your fellow shoppers; plastic bottles mean you could lift an economy-size bottle of juice and should you accidentally drop that bottle, it can be shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also aid you in getting maximum value from a number of the big-ticket items you buy. Plastics help to make portable phones and computers that really are portable. They guide major appliances-like refrigerators or dishwashers-resist corrosion, stay longer and operate more efficiently. Plastic car fenders and body panels resist dings, so you can cruise the supermarket parking lot with full confidence.
Modern packaging-such as heat-sealed plastic pouches and wraps-assists in keeping food fresh and clear of contamination. This means the resources that went into producing that food aren’t wasted. It’s the same thing once you obtain the food home: plastic wraps and resealable containers maintain your leftovers protected-much on the chagrin of kids everywhere. Actually, packaging experts have estimated that every pound of plastic packaging helps to reduce food waste by around 1.7 pounds.
Plastics can also help you bring home more product with less packaging. By way of example, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of any beverage like juice, soda or water. You’d need 3 pounds of aluminum to create home the same amount of product, 8 pounds of steel or higher 40 pounds of glass. Not only do plastic bags require less total energy to create than paper bags, they conserve fuel in shipping. It requires seven trucks to transport 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 almost always be working to do even more with less material. Since 1977, the 2-liter plastic soft drink bottle has gone from weighing 68 grams to simply 47 grams today, representing a 31 percent reduction per bottle. That saved over 180 million pounds of packaging in 2006 for just 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone an identical reduction, weighing 30 percent less than exactly what it did two decades ago.
Doing more with less helps conserve resources in one other way. It helps save energy. In fact, plastics can enjoy a substantial role in energy conservation. Just check out the decision you’re asked to make with the food store 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 make than paper bags, they conserve fuel in shipping. It will require seven trucks to handle the identical quantity 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 heating and air conditioning bills. Furthermore, the United states Department of Energy estimates which use of plastic foam insulation in homes and buildings annually could save over 60 million barrels of oil over other sorts of insulation.
Exactly the same principles apply in appliances including refrigerators and air conditioning units. Plastic parts and insulation have helped to boost their energy efficiency by 30 to 50 % considering that the early 1970s. Again, this energy savings helps reduce your cooling and heating 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 regular source of returned PETE bottles. With incorporating HDPE milk jug recycling within the late 1980s, plastics recycling has grown steadily but relative to competing packaging materials.
Roughly 60 percent of the Usa population-about 148 million people-have accessibility to a plastics recycling program. The 2 common forms of collection are: curbside collection-where consumers place designated plastics inside a special bin being picked up from a public or private hauling company (approximately 8,550 communities take part in curbside recycling) and drop-off centers-where consumers place their recyclables to some centrally located facility (12,000). Most curbside programs collect more than one type of plastic resin; usually both PETE and HDPE. Once collected, the plastics are delivered to a material recovery facility (MRF) or handler for sorting into single resin streams to boost 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 produce new releases including bottles, containers, clothing, carpet, pvc compound, etc. The quantity of companies handling and reclaiming post-consumer plastics today has ended five times greater than in 1986, growing from 310 companies to 1,677 in 1999. The quantity of end uses of recycled plastics keeps growing. The government and state government in addition to many major corporations now support market growth through purchasing preference policies.
At the start of the 1990s, concern over the perceived decrease in landfill capacity spurred efforts by legislators to mandate using recycled materials. Mandates, as a technique of expanding markets, may be troubling. Mandates may neglect to take health, safety and performance attributes into consideration. Mandates distort the economic decisions and can bring about sub optimal financial results. Moreover, they are unable to acknowledge the life span cycle great things about alternatives to the environment, such as the efficient usage of energy and natural resources.
Pyrolysis involves heating plastics in the absence or near shortage of oxygen to break across 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 deadly carbon monoxide are called synthesis gas, or syngas). Contrary to pyrolysis, combustion is undoubtedly an oxidative method that generates heat, carbon dioxide, and water.
Chemical recycling is really a special case where condensation polymers like PET or nylon are chemically reacted to create starting materials.
Source ReductionSource reduction is gaining more attention as being an important resource conservation and solid waste management option. Source reduction, also known as “waste prevention” is identified as “activities to reduce the quantity of material in products and packaging before that material enters the municipal solid waste management system.”