This was designed to lend a better understanding concerning how plastics are manufactured, the different types of plastic as well as their numerous properties and applications.
A plastic the type of synthetic or man-made polymer; similar in several ways to natural resins seen in trees and also other plants. Webster’s Dictionary defines polymers as: any one of various complex organic compounds created by polymerization, effective at being molded, extruded, cast into various shapes and films, or drawn into filaments and after that used as textile fibers.
Just A Little HistoryThe reputation of manufactured plastics dates back greater than a hundred years; however, when compared to many other materials, plastics are relatively modern. Their usage over the past century has allowed society to produce huge technological advances. Although plastics are thought of as an advanced invention, there have been “natural polymers” like amber, tortoise shells and animal horns. These materials behaved just like today’s manufactured plastics and were often used similar to the way manufactured plastics are applied. For example, just before the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes employed to replace glass.
Alexander Parkes unveiled the first man-made plastic at the 1862 Great International Exhibition in the uk. This material-which had been dubbed Parkesine, now called celluloid-was an organic material based on cellulose that once heated could possibly be molded but retained its shape when cooled. Parkes claimed that this new material could do anything that rubber was capable of, yet on the cheap. He had discovered a material which can be transparent along with carved into 1000s of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to generate a synthetic varnish, found the formula for a new synthetic polymer caused by coal tar. He subsequently named the newest substance “Bakelite.” Bakelite, once formed, could not be melted. Simply because of its properties being an electrical insulator, Bakelite was adopted in the production of high-tech objects including cameras and telephones. It was actually also used in producing ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” as the term to illustrate this completely new category of materials.
The first patent for pvc granule, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane have also been discovered during this period.
Plastics failed to really take off until after the First World War, by using petroleum, a substance simpler to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal throughout the hardship times during the World War’s I & II. After World War II, newer plastics, such as polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. Many more would follow and through the 1960s, plastics were within everyone’s reach because of the inexpensive cost. Plastics had thus come that need considering ‘common’-an expression from the consumer society.
Because 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 the most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs whatsoever levels. Plastics are being used such a variety of applications since they are uniquely able to offering a number of properties that provide consumer benefits unsurpassed by many other materials. Also, they are unique for the reason that their properties can be customized for each individual end use application.
Oil and natural gas are the major raw materials utilized to manufacture plastics. The plastics production process often begins by treating elements of oil or natural gas in a “cracking process.” This procedure leads to the conversion of such components into hydrocarbon monomers such as ethylene and propylene. Further processing results in a wider selection of monomers for example styrene, upvc compound, ethylene glycol, terephthalic acid and many others. These monomers are then chemically bonded into chains called polymers. The different mixtures of monomers yield plastics with a variety of properties and characteristics.
PlasticsMany common plastics are produced from hydrocarbon monomers. These plastics are created by linking many monomers together into long chains to make a polymer backbone. Polyethylene, polypropylene and polystyrene are the most prevalent types of these. Below is a diagram of polyethylene, the most basic plastic structure.
Whilst the basic makeup of several plastics is carbon and hydrogen, other elements can be involved. Oxygen, chlorine, fluorine and nitrogen will also be based 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 separated into two distinct groups: thermoplastics and thermosets. Nearly all plastics are thermoplastic, meaning that 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. One other group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating can cause the fabric to decompose instead of melt. Bakelite, poly phenol formaldehyde, is actually a thermoset.
Each plastic has very distinct characteristics, but many plastics possess the following general attributes.
Plastics can be very resistant to chemicals. Consider every one of the cleaning fluids at home which can be packaged in plastic. The warning labels describing what occurs when the chemical makes exposure to skin or eyes or maybe 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 can 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 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 many skiers wear consists of polypropylene as well as the fiberfill in numerous winter jackets is acrylic or polyester.
Generally, plastics are really light in weight with varying degrees of strength. Consider the range of applications, from toys for 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 and some sink. But, compared to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics can be processed in several ways to produce thin fibers or very intricate parts. Plastics might be molded into bottles or elements of cars, such as dashboards and fenders. Some pvcppellet stretch and so are very flexible. Other plastics, such as polyethylene, polystyrene (Styrofoam™) and polyurethane, may be foamed. Plastics may be molded into drums or perhaps be blended with solvents in becoming adhesives or paints. Elastomers and a few plastics stretch and they are very flexible.
Polymers are materials by using a seemingly limitless selection of characteristics and colours. Polymers have lots of inherent properties which can be further enhanced by a wide range 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 can also make possible products which do not readily come from the natural world, including clear sheets, foamed insulation board, and flexible films. Plastics may be molded or formed to generate many different types of products with application in several major markets.
Polymers are often made from petroleum, although not always. Many polymers are made of repeat units produced from natural gas or coal or crude oil. But building block repeat units is often created from renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have been made from renewable materials like cellulose acetate employed for screwdriver handles and gift ribbon. If the building blocks can be created more economically from renewable materials than from fossil 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 enhance their basic mechanical, physical, or chemical properties. Additives are widely used to protect plastics from your degrading results of light, heat, or bacteria; to alter such plastic properties, like melt flow; to deliver color; to offer foamed structure; to deliver flame retardancy; and to provide special characteristics for example improved surface appearance or reduced tack/friction.
Plasticizers are materials included in certain plastics to boost flexibility and workability. Plasticizers are normally found in many plastic film wraps and then in flexible plastic tubing, both of which are normally utilized in food packaging or processing. All plastics used in food contact, for example the additives and plasticizers, are regulated through the Usa Food and Drug Administration (FDA) to make sure that these materials are secure.
Processing MethodsThere are many different processing methods utilized to make plastic products. Below are the four main methods by which plastics are processed to create the merchandise that consumers use, like plastic film, bottles, bags along with other containers.
Extrusion-Plastic pellets or granules are first loaded into a hopper, then fed into an extruder, and that is a long heated chamber, in which it can be moved by the action of a continuously revolving screw. The plastic is melted by a variety of heat from the mechanical work done and by the recent sidewall metal. After the extruder, the molten plastic is forced out using a small opening or die to shape the finished product. As the plastic product extrudes through the die, it really is cooled by air or water. Plastic films and bags are produced by extrusion processing.
Injection molding-Injection molding, plastic pellets or granules are fed from your hopper into a heating chamber. An extrusion screw pushes the plastic with the heating chamber, where material is softened in to a fluid state. Again, mechanical work and hot sidewalls melt the plastic. At the end of this chamber, the resin is forced at high-pressure right into a cooled, closed mold. After the plastic cools to your solid state, the mold opens and also the finished part is ejected. This process is used to make products like butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding can be 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 around the tube and compressed air is going to be blown into the tube to conform the tube towards the interior in the mold as well as to solidify the stretched tube. Overall, the target is to generate a uniform melt, form it in a tube using the desired cross section and blow it in the exact form of the product. This process is commonly used to produce hollow plastic products and its particular principal advantage is being able to produce hollow shapes without having to join several separately injection molded parts. This method can be used to make items for example commercial drums and milk bottles. Another blow molding method is to injection mold an intermediate shape known as a preform and then to heat the preform and blow the high temperature-softened plastic into 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 installed on a device effective at rotation on two axes simultaneously. Plastic granules are placed inside the mold, that is then heated in a oven to melt the plastic Rotation around both axes distributes the molten plastic into a uniform coating on the inside of the mold up until the part is placed by cooling. This method is used to make hollow products, for instance large toys or kayaks.
Durables vs. Non-DurablesAll types of plastic products are classified within the plastic industry to be either a durable or non-durable plastic good. These classifications are employed to make reference to a product’s expected life.
Products with a useful life of 3 years or more are known as durables. They include appliances, furniture, electronic products, automobiles, and building and construction materials.
Products having a useful life of under 3 years are typically referred to 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 obvious, tough and possesses good gas and moisture barrier properties so that it is well suited for carbonated beverage applications and also other food containers. The point that it has high use temperature allows it to be used in applications for example heatable pre-prepared food trays. Its heat resistance and microwave transparency ensure it is a perfect 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) can be used for many packaging applications because it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all types of polyethylene, is restricted to those 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; as well as in injection-molded tub form, for packaging margarine, whipped toppings and deli foods. Because HDPE has good chemical resistance, it can be useful 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 term stability, good weatherability and stable electrical properties. Vinyl products can be broadly split into rigid and versatile 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 related to its potential to deal with most chemicals, imperviousness to attack by bacteria or micro-organisms, corrosion resistance and strength. Flexible vinyl is 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 features a low melting point which makes it popular to be used in applications where heat sealing is important. Typically, LDPE is utilized to produce flexible films such as those employed for dry cleaned garment bags and produce bags. LDPE can also be used to manufacture some flexible lids and bottles, and it is traditionally used in wire and cable applications for its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and it is popular in packaging. It comes with a high melting point, which makes it perfect for hot fill liquids. Polypropylene is found 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 potential to deal with water and to salt and acid solutions that are destructive to metals. Typical applications include ketchup bottles, yogurt containers, medicine bottles, pancake syrup bottles and automobile battery casings.
Polystyrene (PS) is actually a versatile plastic which can be rigid or foamed. General purpose polystyrene is apparent, hard and brittle. Its clarity allows that it is used when transparency is vital, like medical and food packaging, in laboratory ware, and also in certain electronic uses. Expandable Polystyrene (EPS) is often extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers for example egg crates. EPS is additionally directly formed into cups and tubs for dry foods including dehydrated soups. Both foamed sheet and molded tubs are being used extensively in take-out restaurants for lightweight, stiffness and excellent thermal insulation.
If you are aware of it or otherwise, plastics play an important part in your life. Plastics’ versatility permit them to be employed in from car parts to doll parts, from soft drink bottles towards the refrigerators they are stored in. Through the car you drive to operate in the television you watch in your house, plastics help make your life easier and. So, just how would it be that plastics are becoming so widely used? How did plastics get to be the material of choice for countless varied applications?
The simple response is that plastics can offer the items consumers want and want at economical costs. Plastics have the unique capability to be manufactured to satisfy 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 inquiry, plastics can probably satisfy your needs.
If a product consists of plastic, there’s reasons. And chances are the reason why has everything related to helping you to, the customer, get what you want: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just consider the changes we’ve noticed in the food market lately: plastic wrap assists in keeping meat fresh while protecting it in the poking and prodding fingers of your respective fellow shoppers; plastic containers mean you could lift an economy-size bottle of juice and really should you accidentally drop that bottle, it is shatter-resistant. In each case, plastics make your life easier, healthier and safer.
Plastics also help you to get maximum value from a few 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, keep going longer and operate more efficiently. Plastic car fenders and the entire body panels resist dings, to help you cruise the food store parking area with assurance.
Modern packaging-like heat-sealed plastic pouches and wraps-assists in keeping food fresh and free from contamination. Which means the resources that went into producing that food aren’t wasted. It’s the same as soon as you receive the food home: plastic wraps and resealable containers keep the leftovers protected-much towards the chagrin of kids everywhere. In reality, packaging experts have estimated that each pound of plastic packaging is able to reduce food waste by as much as 1.7 pounds.
Plastics can also help you bring home more product with less packaging. As an example, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of the beverage such as juice, soda or water. You’d need 3 pounds of aluminum to bring 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 generate than paper bags, they conserve fuel in shipping. It will require seven trucks to hold a similar variety of paper bags as suits one truckload of plastic bags. Plastics make packaging better, which ultimately conserves resources.
LightweightingPlastics engineers will always be trying to do more with less material. Since 1977, the 2-liter plastic soft drink bottle went from weighing 68 grams to simply 47 grams today, representing a 31 percent reduction per bottle. That saved more than 180 million pounds of packaging in 2006 just for 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone a similar reduction, weighing 30 percent below what it did two decades ago.
Doing more with less helps conserve resources in yet another way. It will help save energy. In reality, plastics may play an important role in energy conservation. Just consider the decision you’re asked to make with the supermarket checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less fresh water than does paper bag manufacture. In addition plastic bags require less total production energy to create than paper bags, they conserve fuel in shipping. It will require seven trucks to handle the identical amount of paper bags as fits in one truckload of plastic bags.
Plastics also assist to conserve energy at home. Vinyl siding and windows help cut energy consumption minimizing heating and cooling bills. Furthermore, the United states Department of Energy estimates that utilize 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 same principles apply in appliances like refrigerators and air conditioners. Plastic parts and insulation have helped to improve their energy efficiency by 30 to fifty percent because the early 1970s. Again, this energy savings helps in reducing your air conditioning bills. And appliances run more quietly than earlier designs that used other materials.
Recycling of post-consumer plastics packaging began during the early 1980s because of state level bottle deposit programs, which produced a consistent 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 U.S. population-about 148 million people-have accessibility to a plastics recycling program. Both common kinds of collection are: curbside collection-where consumers place designated plastics inside a special bin to be acquired with a public or private hauling company (approximately 8,550 communities get involved in curbside recycling) and drop-off centers-where consumers place their recyclables to some centrally located facility (12,000). Most curbside programs collect several form of plastic resin; usually both PETE and HDPE. Once collected, the plastics are transported 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 minimize shipping costs to reclaimers.
Reclamation is the next phase the location where the plastics are chopped into flakes, washed to remove contaminants and sold to terminate users to produce new releases such as bottles, containers, clothing, carpet, clear pvc granule, etc. The amount of companies handling and reclaiming post-consumer plastics today is over 5 times greater than in 1986, growing from 310 companies to 1,677 in 1999. The volume of end uses for recycled plastics keeps growing. The government and state government as well as many major corporations now support market growth through purchasing preference policies.
At the start of the 1990s, concern over the perceived lowering of landfill capacity spurred efforts by legislators to mandate the application of recycled materials. Mandates, as a way of expanding markets, could be troubling. Mandates may neglect to take health, safety and gratifaction attributes under consideration. Mandates distort the economic decisions and can bring about sub optimal financial results. Moreover, they are unable to acknowledge the life cycle benefits associated with choices to the planet, such as the efficient utilization of energy and natural resources.
Pyrolysis involves heating plastics in the absence or near deficiency of oxygen to interrupt on the long polymer chains into small molecules. Under mild conditions polyolefins can yield a petroleum-like oil. Special conditions can yield monomers for example ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and carbon monoxide are classified as synthesis gas, or syngas). As opposed to pyrolysis, combustion is definitely an oxidative method that generates heat, co2, and water.
Chemical recycling can be a special case where condensation polymers like PET or nylon are chemically reacted to make 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 reduce the amount of material in products and packaging before that material enters the municipal solid waste management system.”