This was created to lend a better understanding concerning how plastics are created, the different kinds of plastic as well as their numerous properties and applications.
A plastic is a form 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: any kind of various complex organic compounds created by polymerization, effective at being molded, extruded, cast into various shapes and films, or drawn into filaments and then used as textile fibers.
A Little Bit HistoryThe past of manufactured plastics dates back over a century; however, in comparison to other materials, plastics are relatively modern. Their usage during the last century has allowed society to create huge technological advances. Although plastics are thought of as a modern invention, there have invariably 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 currently applied. For instance, before the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes utilized to replace glass.
Alexander Parkes unveiled the 1st man-made plastic with the 1862 Great International Exhibition inside london. This material-which was dubbed Parkesine, now called celluloid-was an organic material derived from cellulose that when heated could possibly be molded but retained its shape when cooled. Parkes claimed that the new material could do anything that rubber was effective at, yet for less money. He had discovered a material that might be transparent along with carved into 1000s of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to generate a synthetic varnish, came across the formula to get a new synthetic polymer originating from coal tar. He subsequently named the new substance “Bakelite.” Bakelite, once formed, could stop being melted. Due to its properties being an electrical insulator, Bakelite was utilized in producing high-tech objects including cameras and telephones. It was also used in the production of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” because the term to explain this completely new class of materials.
The very first patent for pvc compound, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane was also discovered during this time.
Plastics did not really remove until after the First World War, by using petroleum, a substance quicker to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal throughout the hardship times of World War’s I & II. After The Second World War, newer plastics, such as polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. More would follow and also the 1960s, plastics were within everyone’s reach because of their inexpensive cost. Plastics had thus come to be considered ‘common’-a symbol in the consumer society.
Because the 1970s, we now have witnessed the arrival of ‘high-tech’ plastics found in demanding fields for example health insurance and technology. New types and kinds of plastics with new or improved performance characteristics continue being 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 utilized in these a variety of applications since they are uniquely competent at offering a variety of properties that offer consumer benefits unsurpassed by many other materials. Also, they are unique in this their properties could be customized for every single individual end use application.
Oil and gas are the major raw materials used to manufacture plastics. The plastics production process often begins by treating elements of oil or natural gas inside a “cracking process.” This procedure contributes to the conversion of such components into hydrocarbon monomers including ethylene and propylene. Further processing results in a wider selection of monomers including 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 made from hydrocarbon monomers. These plastics are manufactured 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 actually a diagram of polyethylene, the simplest plastic structure.
However the basic makeup of numerous plastics is carbon and hydrogen, other elements can be involved. Oxygen, chlorine, fluorine and nitrogen are also found in the molecular makeup of several plastics. Polyvinyl chloride (PVC) contains chlorine. Nylon contains nitrogen. Teflon contains fluorine. Polyester and polycarbonates contain oxygen.
Characteristics of Plastics Plastics are separated into two distinct groups: thermoplastics and thermosets. The vast majority of plastics are thermoplastic, which means once the plastic is formed it can be heated and reformed repeatedly. Celluloid is really a thermoplastic. This property provides for easy processing and facilitates recycling. Other group, the thermosets, can not be remelted. Once these plastics are formed, reheating may cause the information to decompose instead of melt. Bakelite, poly phenol formaldehyde, can be a thermoset.
Each plastic has very distinct characteristics, but a majority of plastics possess the following general attributes.
Plastics can be quite resistant against chemicals. Consider all of the cleaning fluids in your home which can be 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 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 stroll using your house will reinforce this idea. Consider all of the electrical appliances, cords, outlets and wiring that happen to be made or covered with plastics. Thermal resistance is evident in the kitchen area with plastic pot and pan handles, coffee pot handles, the foam core of refrigerators and freezers, insulated cups, coolers and microwave cookware. The thermal underwear that many skiers wear is made of polypropylene along with the fiberfill in numerous winter jackets is acrylic or polyester.
Generally, plastics are very light in weight with varying degrees of strength. Consider the range of applications, from toys towards 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 although 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 a variety of methods to produce thin fibers or very intricate parts. Plastics could be molded into bottles or parts of cars, including dashboards and fenders. Some pvcppellet stretch and are very flexible. Other plastics, for example polyethylene, polystyrene (Styrofoam™) and polyurethane, might be foamed. Plastics may be molded into drums or perhaps be together with solvents to become adhesives or paints. Elastomers and some plastics stretch and therefore are very flexible.
Polymers are materials using a seemingly limitless array of characteristics and colours. Polymers have many inherent properties that 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 also can make possible products that do not readily come from the natural world, for example clear sheets, foamed insulation board, and flexible films. Plastics might be molded or formed to generate many different types of products with application in several major markets.
Polymers are generally manufactured from petroleum, but not always. Many polymers are made of repeat units derived from natural gas or coal or oil. But foundation repeat units can occasionally be produced from renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have been produced from renewable materials such as cellulose acetate utilized for screwdriver handles and gift ribbon. Once the foundations can be produced more economically from renewable materials than from standard fuels, either old plastics find new raw materials or new plastics are introduced.
Many plastics are blended with additives because they are processed into finished products. The additives are integrated into plastics to alter and enhance their basic mechanical, physical, or chemical properties. Additives are used to protect plastics through the degrading negative effects of light, heat, or bacteria; to improve such plastic properties, including melt flow; to provide color; to supply foamed structure; to deliver flame retardancy; as well as provide special characteristics including improved surface appearance or reduced tack/friction.
Plasticizers are materials included in certain plastics to boost flexibility and workability. Plasticizers can be found in several plastic film wraps and then in flexible plastic tubing, both of which are generally utilized in food packaging or processing. All plastics utilized in food contact, like the additives and plasticizers, are regulated from the Usa Food and Drug Administration (FDA) to ensure that these materials are safe.
Processing MethodsThere are several different processing methods employed to make plastic products. Listed here are the four main methods in which plastics are processed to form the items that consumers use, like plastic film, bottles, bags along with other containers.
Extrusion-Plastic pellets or granules are first loaded in to a hopper, then fed into an extruder, which is a long heated chamber, through which it can be moved by the act of a continuously revolving screw. The plastic is melted by a combination of heat from your mechanical work done and also by the hot sidewall metal. At the end of the extruder, the molten plastic is forced out using a small opening or die to shape the finished product. As being the plastic product extrudes from your 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 from your hopper in a heating chamber. An extrusion screw pushes the plastic with the heating chamber, in which the material is softened into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. At the conclusion of this chamber, the resin needs at high-pressure in a cooled, closed mold. As soon as the plastic cools into a solid state, the mold opens along with the finished part is ejected. This technique is used to help make products including butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is really a process used jointly with extrusion or injection molding. In a single 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 the tube to conform the tube to the interior of the mold as well as to solidify the stretched tube. Overall, the goal is to make a uniform melt, form it in to a tube with all the desired cross section and blow it into the exact model of the merchandise. This process is used to produce hollow plastic products and its principal advantage is its capability to produce hollow shapes without needing to join two or more separately injection molded parts. This technique is utilized to make items including commercial drums and milk bottles. Another blow molding strategy is to injection mold an intermediate shape called a preform and then to heat the preform and blow the high temperature-softened plastic in to the final shape in a chilled mold. This is the process to create carbonated soft drink bottles.
Rotational Molding-Rotational molding consists of a closed mold placed on a unit capable of rotation on two axes simultaneously. Plastic granules are positioned from the mold, which is then heated inside an oven to melt the plastic Rotation around both axes distributes the molten plastic in to a uniform coating on the inside of the mold up until the part is set by cooling. This procedure can be used to produce hollow products, as an example large toys or kayaks.
Durables vs. Non-DurablesAll types of plastic items are classified in the plastic industry for being either a durable or non-durable plastic good. These classifications are widely used to reference a product’s expected life.
Products having a useful life of 36 months or maybe more are referred to as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products using a useful life of below 36 months 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 has good gas and moisture barrier properties making it well suited for carbonated beverage applications and also 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 help it become an excellent 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 used for most packaging applications because it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all types of polyethylene, is restricted to people food packaging applications that do not require an oxygen or CO2 barrier. In film form, HDPE is utilized in snack food packages and cereal box liners; in blow-molded bottle form, for milk and non-carbonated beverage bottles; and in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it really is useful for packaging many household along with industrial chemicals including 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 lasting stability, good weatherability and stable electrical properties. Vinyl products might be broadly split up 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 can be caused by its effectiveness against most chemicals, imperviousness to attack by bacteria or micro-organisms, corrosion resistance and strength. Flexible vinyl can be 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 employed in film applications due to its toughness, flexibility and transparency. LDPE features a low melting point which makes it popular for use in applications where heat sealing is necessary. Typically, LDPE is utilized to manufacture flexible films such as those used for dry cleaned garment bags and produce bags. LDPE can also be employed to manufacture some flexible lids and bottles, in fact it is popular in wire and cable applications due to its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and it is commonly used in packaging. It possesses a high melting point, which makes it suitable for hot fill liquids. Polypropylene is found 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 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 a versatile plastic that could be rigid or foamed. General purpose polystyrene is obvious, hard and brittle. Its clarity allows so that it is used when transparency is very important, as with 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 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 lightweight, stiffness and excellent thermal insulation.
If you are aware about it or perhaps not, plastics play a significant part in your lifetime. Plastics’ versatility let them be used in anything from car parts to doll parts, from soft drink bottles for the refrigerators these are kept in. In the car you drive to operate within the television you watch in your house, plastics help make your life easier and much better. So how would it be that plastics are becoming so traditionally used? How did plastics get to be the material of choice for so many varied applications?
The straightforward fact is that plastics provides the things consumers want and want at economical costs. Plastics have the unique ability to be manufactured to meet very specific functional needs for consumers. So maybe there’s another question that’s relevant: Precisely what do I want? No matter how you answer this query, plastics can probably suit your needs.
If your product is made of plastic, there’s a reason. And chances are the main reason has everything with regards to helping you to, the consumer, get what you wish: Health. Safety. Performance. and Value. Plastics Have The Ability.
Just take into account the changes we’ve seen in the food market recently: plastic wrap helps keep meat fresh while protecting it through the poking and prodding fingers of your own fellow shoppers; plastic bottles mean it is possible to lift an economy-size bottle of juice and really should you accidentally drop that bottle, it can be shatter-resistant. In each case, plastics make your life easier, healthier and safer.
Plastics also help you to get maximum value from several of the big-ticket items you buy. Plastics make portable phones and computers that basically are portable. They guide major appliances-like refrigerators or dishwashers-resist corrosion, stay longer and operate more effectively. Plastic car fenders and the body panels resist dings, to help you cruise the supermarket parking area with confidence.
Modern packaging-for example heat-sealed plastic pouches and wraps-helps keep food fresh and without any contamination. That means the resources that went into producing that food aren’t wasted. It’s the same as soon as you have the food home: plastic wraps and resealable containers keep the 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 will 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 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 over 40 pounds of glass. Furthermore plastic bags require less total energy to generate than paper bags, they conserve fuel in shipping. It takes seven trucks to carry a similar quantity of paper bags as suits one truckload of plastic bags. Plastics make packaging more efficient, which ultimately conserves resources.
LightweightingPlastics engineers will almost always be endeavoring to do more with less material. Since 1977, the 2-liter plastic soft drink bottle went from weighing 68 grams to just 47 grams today, representing a 31 percent reduction per bottle. That saved over 180 million pounds of packaging in 2006 for just 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone a comparable reduction, weighing 30 percent under just what it did twenty years ago.
Doing more with less helps conserve resources in a different way. It may help save energy. Actually, plastics may play an important role in energy conservation. Just consider the decision you’re motivated to make on the food market 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 generate than paper bags, they conserve fuel in shipping. It will require seven trucks to carry the identical variety of paper bags as fits in one truckload of plastic bags.
Plastics also assistance to conserve energy at your residence. Vinyl siding and windows help cut energy consumption and minimize cooling and heating bills. Furthermore, the Usa Department of Energy estimates designed to use of plastic foam insulation in homes and buildings each and every year could save over 60 million barrels of oil over other sorts of insulation.
The identical principles apply in appliances such as refrigerators and air conditioning units. Plastic parts and insulation have helped to further improve their energy efficiency by 30 to one half since the early 1970s. Again, this energy savings helps in reducing 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 availability of returned PETE bottles. With the addition of HDPE milk jug recycling from the late 1980s, plastics recycling has exploded steadily but relative to competing packaging materials.
Roughly 60 percent in the U.S. population-about 148 million people-have access to a plastics recycling program. The 2 common kinds of collection are: curbside collection-where consumers place designated plastics within a special bin to be gathered 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 a couple of 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 improve product value. The sorted plastics are then baled to lower shipping costs to reclaimers.
Reclamation is the next step where plastics are chopped into flakes, washed to take out contaminants and sold to finish users to manufacture new items including bottles, containers, clothing, carpet, pvc compound, 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 quantity of end ways to use recycled plastics keeps growing. The federal and state government and also many major corporations now support market growth through purchasing preference policies.
At the beginning of the 1990s, concern within the perceived decrease in 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 gratifaction attributes into mind. Mandates distort the economic decisions and can result in sub optimal financial results. Moreover, they are not able to acknowledge the life cycle advantages of alternatives to the environment, including the efficient utilization of energy and natural resources.
Pyrolysis involves heating plastics from the absence or near deficiency 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 such as ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and carbon monoxide are called synthesis gas, or syngas). Contrary to pyrolysis, combustion is an oxidative method that generates heat, co2, and water.
Chemical recycling is actually a special case where condensation polymers for example 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, known as “waste prevention” is described as “activities to minimize the amount of material in products and packaging before that material enters the municipal solid waste management system.”