What Is Plastic?
Plastic is a synthetic or semi-synthetic material whose main character is its plasticity. Plasticity refers to the quality of certain materials to be deformed according to the need of the manufacturing process. It is because of plastic’s plasticity that it can be molded, extruded or compressed. Plastic is primarily made out of different types of polymers. Plastic can be molded into any shape, it can be converted into solids or thin films, it can be extruded into bottles and so on. Plastic is a very versatile material that can be seen in every walk of life. Plastics are durable, cost effective and easy to produce on a large scale. Plastic can be rigid or flexible, depending upon the end product. Plastics can be synthetic or semisynthetic, as well as natural. It can be made from chemicals derived from fossil fuels. Bioplastic is a recent development in which the raw material is renewable like corn or cotton based materials.
The word ‘plastic’ has its roots in the Greek words plastikos and plastos. It means ‘capable of being shaped’ and ‘molded’ respectively. It symbolizes plastic’s pliable nature, which allows it to be molded easily into any product that needs to get manufactured. Plastics are polymers. Polymers are long chained molecules made out of repeating monomers. There are natural and synthetic polymers. Cellulose, a polysaccharide, which is widely found in the plant kingdom, is the classic example of natural polymer. Its monomer is glucose. Synthetic polymers are much longer than natural polymers. They are often made from chemicals derived from fossil fuels. Their monomers are arranged as repetitive units in a long chain. The length of these chains, the branching of these chains, the pattern of packing all vary from polymer to polymer. It is this arrangement that gives them their physical properties like tensile strength, rigidity or flexibility, light weight and so on.
The exceptional properties of synthetic polymers make them highly sought after. Plastic is produced on a massive scale today and used in almost all aspects of our life. So much so that it often becomes a problem. However, new developments like bioplastics, made from corn derivatives helps to counter the unsustainable nature of synthetic plastics.
History Of Plastic Production
The first man made plastic was made by Alexander Parkes while trying to develop a substitute for shellac, which is used for waterproofing. He developed a material called ‘parkesine’ as a substitute for ivory. He introduced it at the London International Exhibition. However the product was not a commercial success. Plastic became commercially viable after the invention of celluloid, which was derived from cellulose.
In 1869, a man named John Wesley Hyatt invented celluloid, in response to an American company’s offer of ten thousand dollars for the development of a material that can substitute the costly and scarce ivory. Celluloid was developed from cellulose by treating the latter with camphor. The result was a highly versatile material that successfully imitated ivory. The discovery of the first plastic material changed the course of history and the market as it was then. Suddenly, production was no longer limited by the lack of natural resources. Celluloid was also praised for saving wildlife from exploitation as it actively became a supplement for ivory. Another advantage of celluloid was its low cost of production. Once obtaining costly natural resources was out of the picture, the production cost reduced and products became more accessible to people. Plastic products like celluloid have played a great role in making the society more consumerist.
Bakelite And After
Bakelite was invented in 1907 by Leo Baekeland. What made bakelite unique was the fact that it was the world’s first completely synthetic polymer. Bakelite was known for its insulation properties, heat resistance and durability. Bakelite resists water and other solvents. It also had excellent plasticity and could be molded into any type of product. Bakelite was more suited for mechanical mass production than celluloid and it soon replaced materials like ‘shellac’ as an insulator in electrical appliances. It was also used in records and telephones.
Bakelite is produced by the reaction of formaldehyde with phenol. It could bind all types of powders and was the first thermosetting plastic in the world. Thermosetting plastics do not soften under heat. It was so useful that it was called ‘the material of a thousand uses’.
Soon, more companies were inspired to develop such other ‘miracle’ materials. New polymers were invented and these replaced the costlier natural materials in several products. Neoprene was invented in 1932, followed by polythene in 1933. Nylon, which was extensively used in World War 2, was made in 1938. It was used for parachute cords and wheels. It was also used in textiles and toothbrushes.
Plastics In World War 2
Plastic was used extensively in World War 2. Plane cockpits were manufactured from plastic materials like Perspex. Natural raw materials like rubber were replaced by synthetic rubber made out of plastic. Plastic materials were also used as insulators for radars. As mentioned earlier, nylon was used on a large scale in World War 2 in order to manufacture parachutes, armor, ropes and so on. The first practically useful polyethylene was developed in England in 1933. It was a lightweight plastic used to insulate radar cabling and thus enabling airplanes to be lighter which gave them a great advantage over German warplanes. Polystyrene which was first developed as an alternative to die cast zinc, went on to be a replacement for rubber and later as expanded polystyrene it became a sturdy thermal insulator and shock absorber. During the war, the production of plastic tripled. The development of the plastic industry was key to the military success of countries like the United States and UK. Synthetic raw materials reduced the amount of money that needed to be spent to procure natural raw materials. Plastic quickly substituted these natural materials.
The production of plastic boomed after World War 2. Plastic was used in several types of products. Plastic was cheap, highly adaptable and very versatile. It had excellent properties of durability, moisture resistance and tensile strength. Different types of plastic were produced which could be used in different capacities. Some were heat resistant, had excellent insulation properties and yet others had great strength to weight ratios. Plastic also provided a great solution for the natural resources crisis. It was an excellent substitute for limited natural resources like ivory. The cost of production drastically reduced as the cheap and affordable plastic quickly took over world markets. After the war, plastic manufacturers focused on making consumer products. Polyester for fabrics was developed in the 1950’s. Polypropylene and HDPE too was developed during the 1950’s. They were used to make a wide variety of products including toys, plastic containers, clothes, jugs, covers and so on.
Plastics In The Future
Even though plastic is highly versatile and extremely useful, it is not without its own problems. Plastic materials are mostly non biodegradable. They do not decay over time, instead they accumulate until it becomes an unsolvable problem. The Great Garbage Patch in the Pacific ocean is an example. However, plastic materials have become an essential aspect of our life. A large part of our day to day activities depend upon plastics. Without the development of plastic, technological advancement would not have taken off the way it did. We would not have had lightweight pocket computers, that is, smartphones, if plastic materials had not been invented. Similarly, plastic has impacted several spheres of life including medicine. Plastic materials have improved the quality of life for a large number of people. It has helped bridge the gap between the rich and poor to some extent as more products that were previously only accessible to the rich were now available to the middle and lower classes as well. The weight of products is reduced with the help of plastic, making it easier to carry around.
This is why it is important to see plastics as a material under development rather than as a pollutant. Plastic materials have improved the life of so many people. So instead of banning them, we must look forward to breakthroughs in plastic development like the invention of bioplastics and biodegradable plastics. Bioplastics are made from corn as the raw material rather than fossil fuels. These are usually plant made plastics. Biodegradable plastics decay, which eliminates the greatest disadvantage of plastic. Development can also occur in recycling methods. Plastics can be recycled back into their constituent materials or into accessories or even into the reinforcement of roads.
Timeline
1856: Parkesine, the first man made plastic, is discovered by the inventor Alexander Parkes. It set the stage for better, commercially more viable plastics.
1869: Celluloid is developed by John Wesley Hyatt in order to replace ivory and horn. He modifies the production process to make celluloid more viable.
1872: Eugen Baumann synthesizes polyvinyl chloride accidentally.
1894: Phonograph records start to be made of shellac.
1898: Polyethylene is synthesized, but not commercially developed.
1907: Leo Baekeland discovers bakelite, the first thermosetting plastic. It was the product of a reaction between phenol and formaldehyde.
1912: Jacques Brandenberger patents a method for the commercial production of cellophane.
1916 – Rolls Royce begins to use phenol formaldehyde
1930: DuPont discovers and produces neoprene.
1931: Shellac records are replaced by vinyl records, introduced by RCA Victor. Vinyl records have a better sound quality than shellac.
1933: An industrially viable method of producing polyethylene is developed by Fawcett and Gibson in England. It was used in war efforts.
1935: The first extruder for thermoplastics was designed by Troester in Germany.
1935: DuPont invents and patents nylon after a 10 million dollar research.
1936: Perspex is used to produce plane canopies.
1938: DuPont chemist Roy Plunkett discovered teflon, that is, polytetrafluoroethylene.
1941: Polyethylene terephthalate or PET, one of the most widely used plastic materials in the world, is discovered in England.
1948: Velcro was invented by George deMestral. It was later patented in 1955
1950: DuPont discovers and begins to manufacture polyester.
1951: Polypropylene is produced from propylene by J. Paul Hogan and Robert L. Banks from Phillips.
1953: Development of polycarbonate by Hermann Schnell at Bayer and Daniel Fox at General Electric.
1954: Expanded polystyrene is developed by Dow Chemical. It is used for insulation and packaging.
1956: The first acetals are patented by DuPont.
1957: Italian firm Montecatini begins the large-scale industrial production of polypropylene.
1965: DuPond develops path breaking material kevlar.
1966: Blow molding of fuel tanks introduced.
1970: HDPE is used to make pressure pipes for gasses in the UK.
1973: PET or polyethylene terephthalate is used to make plastic bottles.
1980: LDPE or low density polyethylene is produced for the first time.
1982: Scientists make the first artificial heart made out of polyurethane, it is implanted in a human.
1987: Invention of polyacetylene by BASF. Polyacetylene has twice the conductivity of copper.
1990: Development of biopol by ICI. Biopol was the first commercially available biodegradable plastic.
Characteristics Of Plastic Material
Plastic is a highly versatile material. Since its development, various types of plastic materials have shaped our consumer lives. Plastic has several properties that make it the unique material it is. They are explained briefly as follows:
Lightweight:
Plastics are way lighter than metals due to their molecular structure. They are light and despite their lightness, they are quite strong. This reduces the weight of products made of plastic. It also makes transportation more convenient and consumer products affordable.
Appearance: Plastics are usually transparent. However, plastics can easily be dyed to any color the product design requires. Shape, like color, can be modified in any manner as required by the product. This ease of molding and manufacturing is why plastics are extremely versatile and popular.
Reactivity towards chemicals: Plastics comparatively have higher resistance as compared to other natural polymers. They can be used with food materials and other liquids and chemicals like acids and alkalis due to their low reactivity.
Thermal resistance: Plastics have very low thermal resistance. They melt down quickly when heat is applied. This is due to the low thermal conductivity of plastics.
Electrical conductivity: Plastics have low electrical conductivity. This is why plastics make good insulators. Certain types of plastics are used specifically for their insulation properties. For this reason, plastics are extremely popular for purposes like switch manufacture, production of bulb holders, wire coating and so on.
Tensile strength:
The tensile strength of plastic decides its toughness. The materials that go into production determine the plastic material’s tensile strength. Metals and metal alloys like steel have greater tensile strength. Plastics like HDPE and nylon have high tensile strength.
Different Types Of Plastic
Plastics come in different shapes, sizes and colors. There are different types of plastic materials and each one has its own specific features and uses. There are reusable plastics, non reusable ones, recyclable plastics, non recyclable plastics, biodegradable plastics and so on. RIC, or the Resin Identification Code is a system used to distinguish between plastic resins. It was in 1988 by the Society of the Plastics Industry. Here are some types of plastic materials you need to know about.
Polyethylene Terephthalate or PET
Polyethylene terephthalate, commonly called PET, is perhaps the most familiar plastic in the world. The RIC code of PET is 1. It is widely used in bottle manufacturing, packaging and textiles. Over 80 million tonnes of PET is produced every year. PET was first patented by John Rex Whinfield, James Tennant Dickson and their employer the Calico Printers’ Association of Manchester, England. DuPont used the trademark Mylar for it in 1951 and in 1973 Nathaniel Wyeth invented the PET bottle which was patented by DuPont.
The monomer of polyethylene terephthalate is ethylene terephthalate. Ethylene terephthalate is produced by the esterification reaction between ethylene glycol and terephthalic acid. Polycondensation of ethylene terephthalate creates the polymer PET. PET can be amorphous and semi crystalline, each form has its own physical properties.
PET is one of the most recyclable plastic produced. It possesses high strength and flexibility. PET is resistant to water and other chemicals. PET is one of the best choices there is for food storage.
Polyvinyl Chloride Or PVC
PVC is one of the most extensively used plastics in the world. PVC can be rigid or flexible. It is used for several purposes like flooring, pipe making and other plumbing implements, furniture, toys and so on.
Polyvinyl chloride was discovered in 1872 by German chemist Eugen. In 1926, Waldo Semon and the B.F. Goodrich Company plasticized polyvinyl chloride with additives like dibutyl phthalate. PVC became more flexible with subsequent developments and soon commercial production began.
HDPE
High density polyethylene is a thermoplastic polymer that is a variant of ethylene. It is used in the manufacture of pipes, jugs and more. HDPE is a commonly used container for milk, juice, soda and other food products. HDPE is a food grade plastic with the resin identification code 2.
HDPE is known for its toughness, rigidity and low cost of production. It has high tensile strength and impact strength, as well as a high melting point. It is durable and quite resistant to chemicals and moisture. Due to its inertness, HDPE is a great choice for the manufacture of food containers.
High density polyethylene was discovered in 1953 by Karl Ziegler of the Kaiser Wilhelm Institute. He used a process of using catalysts like Ziegler-Natta catalyst and low pressure for creating high-density polyethylene.
LDPE
Low density polyethylene is a thermoplastic polymer used to make common packaging materials like bread bags, covers, lids, and so on. It is also used to produce lab equipment. LDPE was the first grade of polyethylene. It was first produced in 1933 by Imperial Chemical Industries using a high pressure process via free radical polymerization. LDPE is made from the monomer ethylene by free radical polymerization.
The features of LDPE include its lightweight nature, toughness, flexibility and high chemical tolerance. It is also a great insulator. LDPE is quite cost effective as well. LDPE has a branched structure, due to which it has a lower density and higher flexibility as compared to HDPE.
Polystyrene
Polystyrene can either be solid or foamed. It is quite cheap and easy to produce. It is used in making multiple products, including food packaging and disposable foodware. Polystyrene is commonly called styrofoam. It is not very advisable to use polystyrene for food as it is highly inflammable and can leach harmful chemicals on contact with hot food.
Polystyrene is an aromatic hydrocarbon polymer made from the monomer styrene. It is hard and stiff. It is also transparent. Polystyrene is widely used in the hospitality industry. It is used to make accessories, toys, cases, containers, boards, trays, utensils and coffee cup lids. Polystyrene was accidentally discovered by the German pharmacist Edward Simon in 1839. Commercial use began nearly a century later by the IG Farben Company.
Polycarbonate
Polycarbonate is a transparent thermoplastic polymer. It has a high impact strength and high dimensional stability. Polycarbonates are amorphous. Polycarbonates are used to build strong, rigid products. It is often used to make lenses and safety goggles. Polycarbonates are also found on mobile phones. They make good insulators. Polycarbonates have a moderate chemical resistance, however it reacts with some chemicals such as alkalis and aromatic and halogenated hydrocarbons.
Polycarbonate was discovered almost simultaneously in Germany and America. In Germany it was discovered by Hermann Schnell from the AG Chemical Company. In America it was discovered by chemist Daniel W. Fox at the General Electric Company.
Polypropylene
Polypropylene is a thermoplastic polymer. The monomer unit of polypropylene is propylene. It is polyolefin. Polypropylene or polypropene, is produced by the chain growth polymerization of its monomer propylene. Polypropylene was discovered in 1954. It was discovered by the Italian chemist Guilio Natta and his assistant Paulo Chini. Catalysts like the Ziegger Natta catalyst were used in the production.
Polypropylene is one of the most commonly produced plastics in the world. It is hard and sturdy, it can stand high temperatures and is fairly durable. It is often used to make tupperware, containers and even disposable diapers. Polypropylene is also used in the automobile industry.
Nylon
Nylon is a thermoplastic polymer, produced from petroleum. It can be converted to fibers, films or other products. Nylon has a lot of desirable features, including its exceptional strength. A thread of nylon is said to be stronger than a wire of steel. Nylon fibers are also stronger than polyester fibers. They are tough and resistant to abrasion. Nylon is easy to wash, and dye. Nylon can be used to make lightweight clothes that have high resilience. It is not only used in textiles, but also in flooring, automobiles, electrical equipment, packaging and so on.
Nylon was the first commercially successful synthetic thermoplastic polymer to be made. It was synthesized by Wallce Hume Carothers at DuPont after a research project that lasted nearly a decade and cost millions of dollars. Nylon was synthesized using diamines on February 28, 1935. In 1938, another type of nylon based on caprolactam was produced by Paul Schlack. It was called Nylon 6.
Polylactic Acid
Polylactic acid is a biodegradable plastic material. It is produced from renewable raw materials. It was discovered in the 1920’s by Wallace Carothers, who invented nylon.
Polylactic acid (PLA) is an aliphatic polyester. It has ester bonds that connect the monomer units. PLA is used for a variety of things, especially in the biomedical field. It is used to make suture threads, bone fixation screws, drug delivery devices and so on.