This was designed to lend a better understanding concerning how plastics are made, the several types of plastic in addition to their numerous properties and applications.
A plastic is a form of synthetic or man-made polymer; similar in lots of ways to natural resins found in trees and also other plants. Webster’s Dictionary defines polymers as: some of various complex organic compounds produced by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments and then used as textile fibers.
A Little HistoryThe background of manufactured plastics dates back over 100 years; however, when compared with many other materials, plastics are relatively modern. Their usage in the last century has allowed society to make huge technological advances. Although plastics are looked at as a contemporary invention, there have been “natural polymers” for example amber, tortoise shells and animal horns. These materials behaved similar to today’s manufactured plastics and were often used similar to the way manufactured plastics are now applied. For example, just before the sixteenth century, animal horns, which become transparent and pale yellow when heated, were sometimes used to replace glass.
Alexander Parkes unveiled the very first man-made plastic on the 1862 Great International Exhibition in the uk. This product-that has been dubbed Parkesine, now called celluloid-was an organic material derived from cellulose once heated may be molded but retained its shape when cooled. Parkes claimed this new material could a single thing that rubber was competent at, yet for less money. He had discovered a material that may 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 for a new synthetic polymer caused by coal tar. He subsequently named the brand new substance “Bakelite.” Bakelite, once formed, could not be melted. Due to the properties as being an electrical insulator, Bakelite was adopted in the creation of high-tech objects including cameras and telephones. It was also employed in the creation of ashtrays and as a substitute for jade, marble and amber. By 1909, Baekland had coined “plastics” as being the term to illustrate this completely new group 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 have also been discovered during this time.
Plastics did not really explode until right after the First World War, if you use petroleum, a substance quicker to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal through the hardship times during World War’s I & II. After The Second World War, newer plastics, for example polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. Many more would follow and also the 1960s, plastics were within everyone’s reach because of their inexpensive cost. Plastics had thus come that need considering ‘common’-a symbol from the consumer society.
Ever since the 1970s, we have witnessed the advent of ‘high-tech’ plastics utilized in demanding fields such as health insurance and technology. New types and kinds of plastics with new or improved performance characteristics continue to be developed.
From daily tasks to our most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs at all levels. Plastics are being used such a wide array of applications as they are uniquely able to offering a variety of properties offering consumer benefits unsurpassed by many other materials. Also, they are unique because their properties can be customized for every individual end use application.
Oil and natural gas would be the major raw materials utilized to manufacture plastics. The plastics production process often begins by treating elements of crude oil or gas in a “cracking process.” This procedure results in the conversion of these components into hydrocarbon monomers like ethylene and propylene. Further processing leads to a wider variety of monomers including styrene, soft pvc granule, ethylene glycol, terephthalic acid and more. These monomers are then chemically bonded into chains called polymers. The different mixtures of monomers yield plastics with a wide array of properties and characteristics.
PlasticsMany common plastics are made from hydrocarbon monomers. These plastics are created by linking many monomers together into long chains produce 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 many plastics is carbon and hydrogen, other elements may also 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 split into two distinct groups: thermoplastics and thermosets. The vast majority of plastics are thermoplastic, meaning that as soon as the plastic is actually created it might be heated and reformed repeatedly. Celluloid can be a thermoplastic. This property permits easy processing and facilitates recycling. The other group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating may cause the fabric to decompose instead of melt. Bakelite, poly phenol formaldehyde, can be a thermoset.
Each plastic has very distinct characteristics, but most plastics hold the following general attributes.
Plastics can be quite resistant to chemicals. Consider every one of the cleaning fluids at your residence that are packaged in plastic. The warning labels describing what occurs as soon as the chemical comes into connection 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 via your house will reinforce this concept. Consider every one of the electrical appliances, cords, outlets and wiring which can 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 also the fiberfill in many winter jackets is acrylic or polyester.
Generally, plastics are incredibly lightweight 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, when compared to the density of stone, concrete, steel, copper, or aluminum, all plastics are lightweight materials.
Plastics might be processed in different approaches to produce thin fibers or very intricate parts. Plastics might be molded into bottles or aspects of cars, including dashboards and fenders. Some pvcppellet stretch and they are very flexible. Other plastics, including polyethylene, polystyrene (Styrofoam™) and polyurethane, might be foamed. Plastics might be molded into drums or even be blended with solvents to become adhesives or paints. Elastomers plus some plastics stretch and so are very flexible.
Polymers are materials by using a seemingly limitless array of characteristics and colors. Polymers have several inherent properties which can be further enhanced by a wide array 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 may also make possible products which do not readily range from natural world, such as clear sheets, foamed insulation board, and versatile films. Plastics could be molded or formed to create many different types of items with application in lots of major markets.
Polymers are generally created from petroleum, but not always. Many polymers are constructed with repeat units based on gas or coal or oil. But building block repeat units can often be created from renewable materials for example polylactic acid from corn or cellulosics from cotton linters. Some plastics have invariably been made out of renewable materials for example cellulose acetate employed for screwdriver handles and gift ribbon. As soon as the building blocks can be made 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 because they are processed into finished products. The additives are integrated into plastics to change and improve their basic mechanical, physical, or chemical properties. Additives are employed to protect plastics from the degrading outcomes of light, heat, or bacteria; to change such plastic properties, such as melt flow; to provide color; to offer foamed structure; to supply flame retardancy; and to provide special characteristics like improved surface appearance or reduced tack/friction.
Plasticizers are materials integrated into certain plastics to boost flexibility and workability. Plasticizers are found in many plastic film wraps and in flexible plastic tubing, both of which are typically employed in food packaging or processing. All plastics employed in food contact, like the additives and plasticizers, are regulated with the United states Food and Drug Administration (FDA) to ensure these materials are safe.
Processing MethodsThere are many different processing methods employed to make plastic products. Below are the four main methods where plastics are processed to produce the products that consumers use, for example plastic film, bottles, bags and 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 action of a continuously revolving screw. The plastic is melted by a mixture of heat in the mechanical work done and also the hot sidewall metal. After the extruder, the molten plastic is forced out by way of a small opening or die to shape the finished product. Since the plastic product extrudes from your die, it 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 the hopper in a heating chamber. An extrusion screw pushes the plastic with the heating chamber, the location where the material is softened right 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 to a cooled, closed mold. After the plastic cools to a solid state, the mold opens and also the finished part is ejected. This method is used to help make products like butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is a process used jointly with extrusion or injection molding. In one form, extrusion blow molding, the die forms a continuous semi-molten tube of thermoplastic material. A chilled mold is clamped across the tube and compressed air will be blown into the tube to conform the tube for the interior of your mold as well as solidify the stretched tube. Overall, the objective is to produce a uniform melt, form it into a tube with the desired cross section and blow it in to the exact form of the item. This process is commonly used to manufacture hollow plastic products along with its principal advantage is its capability to produce hollow shapes and never have to join 2 or more separately injection molded parts. This method is utilized to help make items including commercial drums and milk bottles. Another blow molding approach is to injection mold an intermediate shape referred to as a preform and then to heat the preform and blow the temperature-softened plastic in the final shape in a chilled mold. Here is the process to help make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes a closed mold attached to a machine able to rotation on two axes simultaneously. Plastic granules are placed from the mold, which can be then heated within an oven to melt the plastic Rotation around both axes distributes the molten plastic into a uniform coating within the mold before the part is placed by cooling. This process is commonly used to help make hollow products, for instance large toys or kayaks.
Durables vs. Non-DurablesAll kinds of plastic goods are classified throughout the plastic industry to be either a durable or non-durable plastic good. These classifications are widely used to make reference to a product’s expected life.
Products with a useful lifetime of three years or even more are referred to as durables. They include appliances, furniture, electronic products, automobiles, and building and construction materials.
Products having a useful lifetime of under 36 months are usually called 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 clear, tough and contains good gas and moisture barrier properties rendering it well suited for carbonated beverage applications and also other food containers. The reality that they have high use temperature allows so that it is used in applications for example heatable pre-prepared food trays. Its heat resistance and microwave transparency help it become a great heatable film. Additionally, it 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 utilized for many packaging applications mainly because it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all kinds of polyethylene, is restricted to individuals food packaging applications 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 utilized for packaging many household in addition to industrial chemicals such as detergents, bleach and acids. General uses of HDPE include injection-molded beverage cases, bread trays and also 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 may be broadly separated into rigid and versatile materials. Rigid applications are concentrated in construction markets, which includes pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings could be related to its resistance to 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 used in film applications for its toughness, flexibility and transparency. LDPE has a low melting point so that it is popular for usage in applications where heat sealing is needed. Typically, LDPE is used to manufacture flexible films such as those utilized for dry cleaned garment bags and provide bags. LDPE can also be employed to manufacture some flexible lids and bottles, and is particularly popular in wire and cable applications for its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance which is commonly used in packaging. It possesses 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 big molded parts for automotive and consumer products. Like other plastics, polypropylene has excellent resistance to water and also 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 really a versatile plastic that may be rigid or foamed. General purpose polystyrene is apparent, hard and brittle. Its clarity allows it to be used when transparency is vital, like in medical and food packaging, in laboratory ware, as well as in certain electronic uses. Expandable Polystyrene (EPS) is typically extruded into sheet for thermoforming into trays for meats, fish and cheeses and into containers including egg crates. EPS is also directly formed into cups and tubs for dry foods such as dehydrated soups. Both foamed sheet and molded tubs are being used extensively in take-out restaurants for his or her lightweight, stiffness and excellent thermal insulation.
If you are mindful of it or not, plastics play an essential part in your own life. Plastics’ versatility allow them to be applied in anything from car parts to doll parts, from soft drink bottles on the refrigerators they are saved in. From your car you drive to function into the television you watch in your own home, plastics make your life easier and better. Now how will it be that plastics have become so widely used? How did plastics end up being the material of choice for numerous varied applications?
The basic solution is that plastics provides the points consumers want and require at economical costs. Plastics get the unique ability to be manufactured to satisfy 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 often will satisfy your needs.
If your product consists of plastic, there’s a reason. And odds are the key reason why has everything related to helping you to, the customer, get what you wish: Health. Safety. Performance. and Value. Plastics Have The Ability.
Just take into account the changes we’ve noticed in the grocery store lately: plastic wrap assists in keeping meat fresh while protecting it through the poking and prodding fingers of your respective fellow shoppers; plastic bottles mean you can actually lift an economy-size bottle of juice and must you accidentally drop that bottle, it can be shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also assist you in getting maximum value from several of the big-ticket items you buy. Plastics make portable phones and computers that actually are portable. They guide major appliances-like refrigerators or dishwashers-resist corrosion, go longer and operate more effectively. Plastic car fenders and body panels resist dings, to help you cruise the food store parking lot with full confidence.
Modern packaging-including heat-sealed plastic pouches and wraps-helps keep food fresh and clear of contamination. It means the resources that went into producing that food aren’t wasted. It’s exactly the same thing when you get the food home: plastic wraps and resealable containers keep the leftovers protected-much to the chagrin of kids everywhere. The truth is, packaging experts have estimated that each pound of plastic packaging helps to reduce food waste by up to 1.7 pounds.
Plastics can also help you bring home more product with less packaging. For instance, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of a beverage for example juice, soda or water. You’d need 3 pounds of aluminum to give home the equivalent amount of product, 8 pounds of steel or over 40 pounds of glass. Furthermore plastic bags require less total energy to create than paper bags, they conserve fuel in shipping. It will require seven trucks to hold a similar number of paper bags as suits one truckload of plastic bags. Plastics make packaging better, which ultimately conserves resources.
LightweightingPlastics engineers are always attempting to do even more with less material. Since 1977, the two-liter plastic soft drink bottle has gone 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 only for 2-liter soft drink bottles. The 1-gallon plastic milk jug has undergone an identical reduction, weighing 30 percent below what it really did twenty years ago.
Doing more with less helps conserve resources in a different way. It may help save energy. Actually, plastics can play a substantial role in energy conservation. Just check out the decision you’re required to make at the food store checkout: “Paper or plastic?” Plastic bag manufacture generates less greenhouse gas and uses less fresh water than does paper bag manufacture. Not only do plastic bags require less total production energy to produce than paper bags, they conserve fuel in shipping. It will take seven trucks to carry the identical variety of paper bags as fits in one truckload of plastic bags.
Plastics also assist to conserve energy in your home. Vinyl siding and windows help cut energy consumption and minimize air conditioning bills. Furthermore, the U.S. Department of Energy estimates that utilize of plastic foam insulation in homes and buildings each year could save over 60 million barrels of oil over other kinds of insulation.
A similar principles apply in appliances such as refrigerators and ac units. Plastic parts and insulation have helped to further improve their energy efficiency by 30 to fifty percent since the early 1970s. Again, this energy savings helps in reducing 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 in early 1980s because of state level bottle deposit programs, which produced a regular supply of returned PETE bottles. With incorporating HDPE milk jug recycling in the late 1980s, plastics recycling has expanded steadily but in accordance with competing packaging materials.
Roughly 60 percent of the Usa population-about 148 million people-have accessibility to a plastics recycling program. Both common forms of collection are: curbside collection-where consumers place designated plastics inside a special bin being found with a public or private hauling company (approximately 8,550 communities participate in curbside recycling) and drop-off centers-where consumers place their recyclables to your centrally located facility (12,000). Most curbside programs collect several kind of plastic resin; usually both PETE and HDPE. Once collected, the plastics are shipped to a material recovery facility (MRF) or handler for sorting into single resin streams to increase product value. The sorted plastics are then baled to lessen shipping costs to reclaimers.
Reclamation is the next step in which the plastics are chopped into flakes, washed to remove contaminants and sold to terminate users to produce new products such as bottles, containers, clothing, carpet, pvc compound, etc. The amount of companies handling and reclaiming post-consumer plastics today has ended 5 times in excess of in 1986, growing from 310 companies to 1,677 in 1999. The quantity of end ways to use recycled plastics continues to grow. The government and state government along with many major corporations now support market growth through purchasing preference policies.
At the outset of the 1990s, concern within the perceived lowering of landfill capacity spurred efforts by legislators to mandate the usage of recycled materials. Mandates, as a way of expanding markets, could be troubling. Mandates may neglect to take health, safety and gratification attributes into mind. Mandates distort the economic decisions and can lead to sub optimal financial results. Moreover, they are not able to acknowledge the life span cycle benefits associated with choices to environmental surroundings, for example the efficient use of energy and natural resources.
Pyrolysis involves heating plastics from the absence or near lack 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). As opposed to pyrolysis, combustion is an oxidative method that generates heat, carbon dioxide, and water.
Chemical recycling is a special case where condensation polymers for example 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, known as “waste prevention” is described as “activities to lessen the level of material in products and packaging before that material enters the municipal solid waste management system.”