This was designed to lend a much better understanding concerning how plastics are made, the different kinds of plastic and their numerous properties and applications.
A plastic is a form of synthetic or man-made polymer; similar in several ways to natural resins present in trees and other plants. Webster’s Dictionary defines polymers as: any of various complex organic compounds made by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments then used as textile fibers.
A Bit HistoryThe reputation of manufactured plastics dates back over a century; however, in comparison to many other materials, plastics are relatively modern. Their usage over the past century has allowed society to create huge technological advances. Although plastics are considered to be an advanced invention, there have always been “natural polymers” such as 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 now applied. As an example, ahead of 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 on the 1862 Great International Exhibition inside london. This product-which was dubbed Parkesine, now called celluloid-was an organic material derived from cellulose that after heated might be molded but retained its shape when cooled. Parkes claimed that the new material could do just about anything that rubber was effective at, yet on the cheap. He had discovered a material that might be transparent along with carved into a huge number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to produce a synthetic varnish, stumbled upon the formula to get a new synthetic polymer originating from coal tar. He subsequently named the latest substance “Bakelite.” Bakelite, once formed, could stop being melted. Because of its properties for an electrical insulator, Bakelite was used in the production of high-tech objects including cameras and telephones. It was actually also employed in the production of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” because the term to illustrate this completely new group of materials.
The first patent for pvc pellet, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane was also discovered during this period.
Plastics did not really take off until once 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 through the hardship times during the World War’s I & II. After World War 2, newer plastics, such as polyurethane, polyester, silicones, polypropylene, and polycarbonate joined polymethyl methacrylate and polystyrene and PVC in widespread applications. More would follow and through the 1960s, plastics were within everyone’s reach due to their inexpensive cost. Plastics had thus come that need considering ‘common’-a symbol in the consumer society.
Considering that the 1970s, we have witnessed the arrival of ‘high-tech’ plastics utilized in demanding fields like health insurance and technology. New types and types 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 employed in these a variety of applications since they are uniquely competent at offering numerous properties that supply consumer benefits unsurpassed by many other materials. Also, they are unique in this their properties could be customized for every individual end use application.
Oil and gas would be the major raw materials utilized to manufacture plastics. The plastics production process often begins by treating aspects of crude oil or gas inside a “cracking process.” This procedure results in the conversion of these components into hydrocarbon monomers including ethylene and propylene. Further processing results in a wider selection of monomers for example styrene, soft pvc granule, ethylene glycol, terephthalic acid and many 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 prevalent samples of these. Below can be a diagram of polyethylene, the most basic plastic structure.
However the basic makeup of several 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 up into two distinct groups: thermoplastics and thermosets. Nearly all plastics are thermoplastic, meaning that when the plastic is created it could be heated and reformed repeatedly. Celluloid can be a thermoplastic. This property allows for easy processing and facilitates recycling. Other group, the thermosets, simply cannot be remelted. Once these plastics are formed, reheating will result in the content to decompose instead of melt. Bakelite, poly phenol formaldehyde, can be a thermoset.
Each plastic has very distinct characteristics, but most plastics have the following general attributes.
Plastics can be very immune to chemicals. Consider all of the cleaning fluids in your home that happen to be packaged in plastic. The warning labels describing what happens as soon as the chemical enters into exposure to skin or eyes or perhaps is ingested, emphasizes the chemical resistance of these materials. While solvents easily dissolve some plastics, other plastics provide safe, non-breakable packages for aggressive solvents.
Plastics might be both thermal and electrical insulators. A stroll via your house will reinforce this idea. Consider all of the electrical appliances, cords, outlets and wiring that are made or engrossed in plastics. Thermal resistance is evident with the cooking 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 a great many skiers wear is made of polypropylene and also the fiberfill in many winter jackets is acrylic or polyester.
Generally, plastics are really lightweight with varying levels of strength. Consider the plethora of applications, from toys on 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 might be processed in a variety of methods to produce thin fibers or very intricate parts. Plastics might be molded into bottles or components of cars, like dashboards and fenders. Some pvcppellet stretch and they are very flexible. Other plastics, for example polyethylene, polystyrene (Styrofoam™) and polyurethane, might be foamed. Plastics can be molded into drums or even be together with solvents to get adhesives or paints. Elastomers plus some plastics stretch and they are very flexible.
Polymers are materials with a seemingly limitless selection of characteristics and colors. Polymers have many inherent properties which can be further enhanced by an array of additives to broaden their uses and applications. Polymers can be created to mimic cotton, silk, and wool fibers; porcelain and marble; and aluminum and zinc. Polymers may also make possible products that do not readily come from the natural world, like clear sheets, foamed insulation board, and versatile films. Plastics may be molded or formed to produce many different types of products with application in many major markets.
Polymers tend to be made from petroleum, but not always. Many polymers are made of repeat units produced by gas or coal or oil. But foundation repeat units is often made out of renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have invariably been made from renewable materials such as cellulose acetate useful for screwdriver handles and gift ribbon. If the building blocks can be done more economically from renewable materials than from energy sources, either old plastics find new raw materials or new plastics are introduced.
Many plastics are combined with additives because they are processed into finished products. The additives are incorporated into plastics to change and boost their basic mechanical, physical, or chemical properties. Additives are employed to protect plastics in the degrading negative effects of light, heat, or bacteria; to modify such plastic properties, like melt flow; to deliver color; to deliver foamed structure; to provide flame retardancy; and also to provide special characteristics for example improved surface appearance or reduced tack/friction.
Plasticizers are materials incorporated into certain plastics to increase flexibility and workability. Plasticizers are located in many plastic film wraps and also in flexible plastic tubing, each of which are commonly found in food packaging or processing. All plastics used in food contact, such as the additives and plasticizers, are regulated with the Usa Food and Drug Administration (FDA) to make certain that these materials are safe.
Processing MethodsThere are a couple of different processing methods employed to make plastic products. Listed here are the four main methods through which plastics are processed to make the products that consumers use, including plastic film, bottles, bags as well as other containers.
Extrusion-Plastic pellets or granules are first loaded into a hopper, then fed into an extruder, which is a long heated chamber, whereby it can be moved by the act of a continuously revolving screw. The plastic is melted by a variety of heat from your 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. Because the plastic product extrudes in the die, it is actually 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 a hopper in a heating chamber. An extrusion screw pushes the plastic throughout the heating chamber, where the material is softened in to a fluid state. Again, mechanical work and hot sidewalls melt the plastic. Following this chamber, the resin needs at high pressure in to a cooled, closed mold. When the plastic cools to some solid state, the mold opens and the finished part is ejected. This procedure is commonly used to help make products including butter tubs, yogurt containers, closures and fittings.
Blow molding-Blow molding is a process used in conjunction 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 around the tube and compressed air is going to be blown in the tube to conform the tube on the interior of the mold and also to solidify the stretched tube. Overall, the aim is to generate a uniform melt, form it in a tube using the desired cross section and blow it in the exact model of the item. This technique can be used to manufacture hollow plastic products as well as its principal advantage is its capability to produce hollow shapes without needing to join two or more separately injection molded parts. This method can be used to create items like commercial drums and milk bottles. Another blow molding technique is to injection mold an intermediate shape known as a preform after which to heat the preform and blow the warmth-softened plastic to the final shape in a chilled mold. This is the process to help make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes closed mold placed on a unit capable of rotation on two axes simultaneously. Plastic granules are put in the mold, that is then heated in an oven to melt the plastic Rotation around both axes distributes the molten plastic right into a uniform coating on the inside of the mold until the part is defined by cooling. This procedure is commonly used to make hollow products, by way of example 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 used to make reference to a product’s expected life.
Products by using a useful life of 36 months or higher are termed as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products by using a useful life of below 36 months are generally 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 apparent, tough and it has good gas and moisture barrier properties rendering it perfect for carbonated beverage applications along with other food containers. The fact that they have high use temperature allows that it is employed in applications such as heatable pre-prepared food trays. Its heat resistance and microwave transparency ensure it is a great heatable film. Furthermore, it finds applications 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 most packaging applications since it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like all sorts of polyethylene, is limited to people food packaging applications which do not require an oxygen or CO2 barrier. In film form, HDPE can be used in snack food packages and cereal box liners; in blow-molded bottle form, for milk and non-carbonated beverage bottles; and 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 as well as industrial chemicals for example 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, lasting stability, good weatherability and stable electrical properties. Vinyl products might be broadly separated into rigid and versatile materials. Rigid applications are concentrated in construction markets, including pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings could be attributed to its resistance to most chemicals, imperviousness to attack by bacteria or micro-organisms, corrosion resistance and strength. Flexible vinyl is utilized 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 the toughness, flexibility and transparency. LDPE has a low melting point so that it is popular for use in applications where heat sealing is necessary. Typically, LDPE is commonly used to produce flexible films including those employed for dry cleaned garment bags and produce bags. LDPE is also employed to manufacture some flexible lids and bottles, in fact it is widely used in wire and cable applications for its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance which is popular in packaging. It has a high melting point, so that it is well suited for hot fill liquids. Polypropylene is 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 effectiveness against water as well as salt and acid solutions which are 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 may be rigid or foamed. General purpose polystyrene is clear, hard and brittle. Its clarity allows that it is used when transparency is essential, like in 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 also directly formed into cups and tubs for dry foods like dehydrated soups. Both foamed sheet and molded tubs are being used extensively in take-out restaurants for lightweight, stiffness and ideal thermal insulation.
Whether you are aware about it or otherwise, plastics play an essential part in your daily life. Plastics’ versatility permit them to be utilized in from car parts to doll parts, from soft drink bottles on the refrigerators they are saved in. In the car you drive to work in the television you watch in the home, plastics make your life easier and. Now how is it that plastics have become so popular? How did plastics end up being the material preferred by numerous varied applications?
The simple solution is that plastics can offer the points consumers want and desire at economical costs. Plastics get the unique capability to be manufactured in order to meet very specific functional needs for consumers. So maybe there’s another question that’s relevant: Precisely what do I want? Irrespective of how you answer this inquiry, plastics often will satisfy your needs.
If your product consists of plastic, there’s grounds. And chances are the reason has everything with regards to helping you, the buyer, get what you need: Health. Safety. Performance. and Value. Plastics Have The Ability.
Just think about the changes we’ve observed in the food store recently: plastic wrap assists in keeping meat fresh while protecting it from your poking and prodding fingers of the 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 is actually shatter-resistant. In each case, plastics make your life easier, healthier and safer.
Plastics also help you get maximum value from a number of the big-ticket stuff you buy. Plastics make portable phones and computers that truly are portable. They help major appliances-like refrigerators or dishwashers-resist corrosion, keep going longer and operate more efficiently. Plastic car fenders and body panels resist dings, so you can cruise the food store parking lot with confidence.
Modern packaging-including heat-sealed plastic pouches and wraps-helps keep food fresh and free of contamination. This means the time that went into producing that food aren’t wasted. It’s the same after you get the food home: plastic wraps and resealable containers maintain your leftovers protected-much towards the chagrin of kids everywhere. In fact, packaging experts have estimated that every pound of plastic packaging helps to reduce food waste by as much as 1.7 pounds.
Plastics can also help you bring home more product with less packaging. For example, just 2 pounds of plastic can deliver 1,300 ounces-roughly 10 gallons-of a beverage including juice, soda or water. You’d need 3 pounds of aluminum to take home the equivalent 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 will take seven trucks to transport exactly the same amount of paper bags as suits one truckload of plastic bags. Plastics make packaging more efficient, which ultimately conserves resources.
LightweightingPlastics engineers are always endeavoring to do more with less material. Since 1977, the 2-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 the same reduction, weighing 30 percent below what it did two decades ago.
Doing more with less helps conserve resources in a different way. It may help save energy. In fact, plastics can enjoy a significant role in energy conservation. Just consider the decision you’re required 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. Not only do plastic bags require less total production energy to make than paper bags, they conserve fuel in shipping. It will take seven trucks to handle the identical number of paper bags as suits one truckload of plastic bags.
Plastics also assist to conserve energy in your home. Vinyl siding and windows help cut energy consumption and lower heating and cooling bills. Furthermore, the Usa Department of Energy estimates which use of plastic foam insulation in homes and buildings every year could save over 60 million barrels of oil over other kinds of insulation.
The same principles apply in appliances such as refrigerators and air conditioners. Plastic parts and insulation have helped to further improve their energy efficiency by 30 to 50 % because 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 other materials.
Recycling of post-consumer plastics packaging began in the early 1980s due to state level bottle deposit programs, which produced a regular flow of returned PETE bottles. With the addition of HDPE milk jug recycling within the late 1980s, plastics recycling has exploded steadily but relative to competing packaging materials.
Roughly 60 percent from the United states population-about 148 million people-gain access to a plastics recycling program. The 2 common types of collection are: curbside collection-where consumers place designated plastics in a special bin to get found with a public or private hauling company (approximately 8,550 communities get involved in curbside recycling) and drop-off centers-where consumers get their recyclables to your centrally located facility (12,000). Most curbside programs collect multiple sort 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 boost product value. The sorted plastics are then baled to lower shipping costs to reclaimers.
Reclamation is the next step where the plastics are chopped into flakes, washed to take out contaminants and sold to terminate users to produce new services for example bottles, containers, clothing, carpet, pvc compound, etc. The amount of companies handling and reclaiming post-consumer plastics today is finished five times in excess of in 1986, growing from 310 companies to 1,677 in 1999. The amount of end ways to use recycled plastics is 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 decrease in landfill capacity spurred efforts by legislators to mandate using recycled materials. Mandates, as a method of expanding markets, can be troubling. Mandates may forget to take health, safety and satisfaction attributes into mind. Mandates distort the economic decisions and can result in sub optimal financial results. Moreover, they are not able to acknowledge the lifespan cycle benefits of choices to the planet, like the efficient consumption of energy and natural resources.
Pyrolysis involves heating plastics inside the absence or near shortage of oxygen to get rid of on the long polymer chains into small molecules. Under mild conditions polyolefins can yield a petroleum-like oil. Special conditions can yield monomers including ethylene and propylene. Some gasification processes yield syngas (mixtures of hydrogen and deadly carbon monoxide are called synthesis gas, or syngas). Unlike pyrolysis, combustion is an oxidative procedure that generates heat, co2, and water.
Chemical recycling is a special case where condensation polymers such as 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, known as “waste prevention” is identified as “activities to reduce the amount of material in products and packaging before that material enters the municipal solid waste management system.”