This is designed to lend an improved 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 lots of ways to natural resins seen in trees as well as 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 after which used as textile fibers.
A Bit HistoryThe past of manufactured plastics goes back over a century; however, in comparison to other materials, plastics are relatively modern. Their usage in the last century has enabled society to produce huge technological advances. Although plastics are considered to be an advanced invention, there have invariably been “natural polymers” like 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. 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 with the 1862 Great International Exhibition in London. This product-which was dubbed Parkesine, now called celluloid-was an organic material based on cellulose that when heated may be molded but retained its shape when cooled. Parkes claimed that the new material could do just about anything that rubber was competent at, yet at a lower price. He had discovered a material that may be transparent and also carved into a huge number of different shapes.
In 1907, chemist Leo Hendrik Baekland, while striving to make a synthetic varnish, discovered the formula for a new synthetic polymer originating from coal tar. He subsequently named the newest substance “Bakelite.” Bakelite, once formed, could not be melted. Because of its properties being an electrical insulator, Bakelite was applied in the creation of high-tech objects including cameras and telephones. It absolutely was also used in the creation of ashtrays and as an alternative for jade, marble and amber. By 1909, Baekland had coined “plastics” as being the term to describe this completely new type of materials.
The initial patent for pvc granule, a substance now used widely in vinyl siding and water pipes, was registered in 1914. Cellophane was also discovered during this time.
Plastics failed to really explode until after the First World War, with the aid of petroleum, a substance simpler to process than coal into raw materials. Plastics served as substitutes for wood, glass and metal through the hardship times of 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. More would follow and also by the 1960s, plastics were within everyone’s reach because of the inexpensive cost. Plastics had thus come to be considered ‘common’-an expression of your consumer society.
Since the 1970s, we have now witnessed the arrival of ‘high-tech’ plastics found in demanding fields such as health and technology. New types and forms of plastics with new or improved performance characteristics continue to be developed.
From daily tasks to your most unusual needs, plastics have increasingly provided the performance characteristics that fulfill consumer needs by any means levels. Plastics are used such a variety of applications since they are uniquely capable of offering a variety of properties offering consumer benefits unsurpassed by many other materials. Also, they are unique in this their properties may be customized for each individual end use application.
Oil and natural gas would be the major raw materials used to manufacture plastics. The plastics production process often begins by treating elements of oil or gas in the “cracking process.” This procedure brings about the conversion of these components into hydrocarbon monomers such as ethylene and propylene. Further processing leads to a wider variety of monomers such as styrene, upvc compound, ethylene glycol, terephthalic acid and more. These monomers are then chemically bonded into chains called polymers. The numerous combinations of monomers yield plastics with a variety of properties and characteristics.
PlasticsMany common plastics are made of hydrocarbon monomers. These plastics are produced by linking many monomers together into long chains to make a polymer backbone. Polyethylene, polypropylene and polystyrene are the most typical types of these. Below is actually a diagram of polyethylene, the most basic plastic structure.
Even though the basic makeup of numerous plastics is carbon and hydrogen, other elements can also be involved. Oxygen, chlorine, fluorine and nitrogen can also be based in the molecular makeup of numerous 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. Virtually all plastics are thermoplastic, which means that when the plastic is created it can be heated and reformed repeatedly. Celluloid is a thermoplastic. This property allows for easy processing and facilitates recycling. One other group, the thermosets, can not be remelted. Once these plastics are formed, reheating will cause the information to decompose as opposed to melt. Bakelite, poly phenol formaldehyde, is really a thermoset.
Each plastic has very distinct characteristics, but a majority of plastics possess the following general attributes.
Plastics are often very resistant against chemicals. Consider every one of the cleaning fluids in your house that are packaged in plastic. The warning labels describing what happens as soon as the chemical makes experience of skin or eyes or maybe 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 can be both thermal and electrical insulators. A walk by your house will reinforce this concept. Consider all of the electrical appliances, cords, outlets and wiring that happen to be made or engrossed in 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 numerous skiers wear is made from polypropylene along with the fiberfill in several winter jackets is acrylic or polyester.
Generally, plastics are extremely light-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®, that is utilized 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 strategies to produce thin fibers or very intricate parts. Plastics may be molded into bottles or elements of cars, such as dashboards and fenders. Some pvcppellet stretch and therefore are very flexible. Other plastics, such as polyethylene, polystyrene (Styrofoam™) and polyurethane, can be foamed. Plastics could be molded into drums or perhaps be mixed with solvents in becoming adhesives or paints. Elastomers and some plastics stretch and they are very flexible.
Polymers are materials with a seemingly limitless array of characteristics and colors. Polymers have lots of inherent properties that may be further enhanced by a wide range 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 range from natural world, like clear sheets, foamed insulation board, and versatile films. Plastics may be molded or formed to make many kinds of products with application in many major markets.
Polymers are often made of petroleum, although not always. Many polymers are made of repeat units derived from natural gas or coal or crude oil. But building block repeat units can often be created from renewable materials including polylactic acid from corn or cellulosics from cotton linters. Some plastics have always been created from renewable materials such as cellulose acetate utilized for screwdriver handles and gift ribbon. If the foundations can be produced more economically from renewable materials than from fossil fuels, either old plastics find new raw materials or new plastics are introduced.
Many plastics are combined with additives since 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 widely used to protect plastics through the degrading outcomes of light, heat, or bacteria; to improve such plastic properties, such as melt flow; to supply color; to deliver foamed structure; to deliver flame retardancy; as well as provide special characteristics like improved surface appearance or reduced tack/friction.
Plasticizers are materials included in certain plastics to enhance flexibility and workability. Plasticizers are normally found in many plastic film wraps and in flexible plastic tubing, each of which are normally employed in food packaging or processing. All plastics used in food contact, such as the additives and plasticizers, are regulated with the United states Food and Drug Administration (FDA) to make certain that these materials are safe.
Processing MethodsThere are a couple of different processing methods used to make plastic products. Below are the 4 main methods by which plastics are processed to form the products that consumers use, like plastic film, bottles, bags along with other containers.
Extrusion-Plastic pellets or granules are first loaded in a hopper, then fed into an extruder, which is a long heated chamber, whereby it is actually moved by the action of a continuously revolving screw. The plastic is melted by a mix of heat from the mechanical work done and also by the sidewall metal. At the end of the extruder, the molten plastic needs out by way of a small opening or die to shape the finished product. Because the plastic product extrudes through the die, it can be 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 into a heating chamber. An extrusion screw pushes the plastic through the heating chamber, in which the material is softened into a fluid state. Again, mechanical work and hot sidewalls melt the plastic. After this chamber, the resin is forced at high pressure in to a cooled, closed mold. As soon as the plastic cools to your solid state, the mold opens along with the finished part is ejected. This process is commonly used to create products for example 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 will be blown to the tube to conform the tube for the interior of your mold as well as to solidify the stretched tube. Overall, the objective is to produce a uniform melt, form it right into a tube with the desired cross section and blow it into the exact form of the product. This process can be used to manufacture hollow plastic products along with its principal advantage is its ability to produce hollow shapes without needing to join 2 or more separately injection molded parts. This procedure is utilized to produce items including commercial drums and milk bottles. Another blow molding method is to injection mold an intermediate shape termed as a preform and then to heat the preform and blow the warmth-softened plastic in the final shape inside a chilled mold. This is the process to make carbonated soft drink bottles.
Rotational Molding-Rotational molding includes closed mold placed on a unit effective at rotation on two axes simultaneously. Plastic granules are put in the mold, which is then heated in a oven to melt the plastic Rotation around both axes distributes the molten plastic right into a uniform coating on the inside of the mold up until the part is placed by cooling. This procedure is commonly used to produce hollow products, as an example large toys or kayaks.
Durables vs. Non-DurablesAll forms of plastic items are classified throughout the plastic industry for being either a durable or non-durable plastic good. These classifications are employed to reference a product’s expected life.
Products using a useful life of 3 years or maybe more are termed as durables. They include appliances, furniture, consumer electronics, automobiles, and building and construction materials.
Products by using a useful lifetime of under 36 months 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 apparent, tough and has good gas and moisture barrier properties which makes it well suited for carbonated beverage applications and other food containers. The point that it has high use temperature allows that it is utilized in applications including heatable pre-prepared food trays. Its heat resistance and microwave transparency ensure it is an ideal 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 utilized for many packaging applications because it provides excellent moisture barrier properties and chemical resistance. However, HDPE, like a variety of polyethylene, has limitations to the 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 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 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 could be broadly split into rigid and flexible materials. Rigid applications are concentrated in construction markets, which include pipe and fittings, siding, rigid flooring and windows. PVC’s success in pipe and fittings may 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 used in film applications due to its toughness, flexibility and transparency. LDPE carries a low melting point rendering it popular to be used in applications where heat sealing is needed. Typically, LDPE is commonly used to produce flexible films such as those useful for dry cleaned garment bags and provide bags. LDPE is also accustomed to manufacture some flexible lids and bottles, which is commonly used in wire and cable applications for its stable electrical properties and processing characteristics.
Polypropylene (PP) has excellent chemical resistance and it is widely used in packaging. It comes with a high melting point, so that it is ideal 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 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 really a versatile plastic that can be rigid or foamed. General purpose polystyrene is apparent, hard and brittle. Its clarity allows so that it is used when transparency is important, as in medical and food packaging, in laboratory ware, and then in certain electronic uses. Expandable Polystyrene (EPS) is normally 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 including dehydrated soups. Both foamed sheet and molded tubs are used extensively in take-out restaurants for lightweight, stiffness and ideal thermal insulation.
If you are aware about it or otherwise, plastics play an important part in your life. Plastics’ versatility let them be applied in anything from car parts to doll parts, from soft drink bottles for the refrigerators they may be saved in. In the car you drive to operate into the television you watch in your own home, plastics help make your life easier and much better. Now how could it be that plastics have grown to be so popular? How did plastics end up being the material of choice for numerous varied applications?
The simple solution is that plastics offers the items consumers want and desire at economical costs. Plastics possess the unique capacity to be manufactured to fulfill very specific functional needs for consumers. So maybe there’s another question that’s relevant: What do I want? Regardless how you answer this query, plastics can probably suit your needs.
In case a product is constructed of plastic, there’s a reason. And odds are the reason why has everything to do with helping you, the individual, get what you need: Health. Safety. Performance. and Value. Plastics Make It Possible.
Just think about the changes we’ve observed in the food market lately: plastic wrap helps keep meat fresh while protecting it from your poking and prodding fingers of your fellow shoppers; plastic bottles mean you can easily lift an economy-size bottle of juice and should you accidentally drop that bottle, it is shatter-resistant. In each case, plastics help make your life easier, healthier and safer.
Plastics also aid you in getting maximum value from a few of the big-ticket things you buy. Plastics help to make portable phones and computers that truly are portable. They assist 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 grocery store parking lot with full confidence.
Modern packaging-including heat-sealed plastic pouches and wraps-helps keep food fresh and free from contamination. Which means the time that went into producing that food aren’t wasted. It’s the exact same thing after you obtain the food home: plastic wraps and resealable containers keep the leftovers protected-much for the chagrin of kids everywhere. Actually, packaging experts have estimated that every pound of plastic packaging is effective in reducing food waste by approximately 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 any beverage including juice, soda or water. You’d need 3 pounds of aluminum to create home the same amount of product, 8 pounds of steel or higher 40 pounds of glass. Not only do plastic bags require less total energy to make than paper bags, they conserve fuel in shipping. It will require seven trucks to hold the same amount of paper bags as fits in one truckload of plastic bags. Plastics make packaging more efficient, which ultimately conserves resources.
LightweightingPlastics engineers will almost always be attempting 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 under what it really did twenty years ago.
Doing more with less helps conserve resources in one other way. It will help save energy. Actually, plastics can enjoy an important role in energy conservation. Just look at the decision you’re asked to make in the food store 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 make than paper bags, they conserve fuel in shipping. It takes seven trucks to transport exactly the same number of paper bags as suits one truckload of plastic bags.
Plastics also assist to conserve energy in your house. Vinyl siding and windows help cut energy consumption and minimize air conditioning bills. Furthermore, the U.S. 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.
A similar principles apply in appliances like refrigerators and ac units. Plastic parts and insulation have helped to improve their energy efficiency by 30 to one half because the early 1970s. Again, this energy savings helps in reducing your heating and cooling bills. And appliances run more quietly than earlier designs that used many other materials.
Recycling of post-consumer plastics packaging began in the 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 inside the late 1980s, plastics recycling continues to grow steadily but relative to competing packaging materials.
Roughly 60 percent in the Usa population-about 148 million people-gain access to a plastics recycling program. Both the common types of collection are: curbside collection-where consumers place designated plastics in a special bin to become gathered by a public or private hauling company (approximately 8,550 communities take part 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 kind of plastic resin; usually both PETE and HDPE. Once collected, the plastics are sent to a material recovery facility (MRF) or handler for sorting into single resin streams to boost product value. The sorted plastics are then baled to minimize shipping costs to reclaimers.
Reclamation is the next step where the plastics are chopped into flakes, washed to get rid of contaminants and sold to end users to produce new releases for example bottles, containers, clothing, carpet, transparent pvc compound, etc. The quantity of companies handling and reclaiming post-consumer plastics today has finished five times greater than in 1986, growing from 310 companies to 1,677 in 1999. The amount of end uses for recycled plastics keeps growing. The federal and state government and also many major corporations now support market growth through purchasing preference policies.
Early in the 1990s, concern over the perceived reduction of landfill capacity spurred efforts by legislators to mandate the usage of recycled materials. Mandates, as a way of expanding markets, can be troubling. Mandates may neglect to take health, safety and gratification attributes under consideration. Mandates distort the economic decisions and can result in sub optimal financial results. Moreover, they are not able to acknowledge the lifespan cycle great things about options to the surroundings, such as the efficient usage of energy and natural resources.
Pyrolysis involves heating plastics from the absence or near absence of oxygen to break 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 deadly carbon monoxide are known as synthesis gas, or syngas). As opposed to pyrolysis, combustion is undoubtedly an oxidative method that generates heat, co2, and water.
Chemical recycling is really a special case where condensation polymers for example 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, typically referred to 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.”