Classification of plastics pdf
Plastic is easy to mold when exposed to high temperatures, although if the temperature is too high it can decompose. For this reason, plastic is said to possess properties of flexibility and elasticity as it adapts to certain shapes.
Once it reaches its final form, plastic is quite resistant and difficult to degrade. Its uses are varied, it is used for the construction of bottles, tables, vases, among others.
In 1860, in a contest whose reward was 10,000 dollars, John Wesley Hyatt proposed dissolving cellulose in a solution of ethanol and camphor, and obtained celluloid (considered the first thermoplastic) with this simple process. At the time, the search was on for a substitute for natural ivory (which was used to make, for example, billiard balls).
Plastic is resistant to deterioration. However, it is important to mention that in many cases resistance is not synonymous with sanitation. A plastic bottle may or may not be reusable, depending on the type of plastic from which the bottle is made. Each plastic object should have a label that specifies whether it is reusable or not.
PET plastic is one of the plastics we find most frequently in water bottles, juices, beverages and textiles, it is also the plastic that most recycle points and grassroots recyclers receive, and one of the easiest to replace, it is enough to start using a reusable bottle to begin to stop using PET.
PET was first produced in 1941 to be used as a textile fiber to help make up for the wartime shortage of cotton. In the 1950s it was used in the food industry as an ambassador, and its production became widespread in the 1970s when it began to be used as a rigid container for beverages and carbonated water.
It is generally known to be used in pipes, but it can also be found in oil bottles, shampoo, medicine containers, meat packaging, sausages, tablecloths, to name a few. PVC is considered toxic due to the use of chlorine in its manufacture, and also emanates vinyl chloride, which can pass into liquids (pipes or water bottles) as the temperature rises.
Classification and use of plastics
Plastic is a material made up of organic or synthetic compounds that have the property of being malleable and therefore can be molded into solid objects of various shapes. This property gives plastics a wide variety of applications. Their name derives from plasticity, a property of materials, which refers to the ability to deform without breaking.
In 1839 Goodyear in the United States and Hancock in England developed in parallel the vulcanization of rubber, i.e. the hardening of rubber and its increased resistance to cold. This was the beginning of the commercial success of thermosetting polymers. The plastics industry began with the development of plastics.
The plastics industry begins with the development of the first thermoset plastics by Baekeland in 1909. Baekeland produced the first synthetic polymer and also developed the plastic molding process, which enabled him to produce various articles of commerce. These early plastics were named Bakelite in honor of their discoverer. Bakelite is formed by a condensation reaction of phenol with formaldehyde. Baekeland’s first synthetic polymer is called bakelite.
Classification of plastics according to their origin
Not all plastic containers are the same. A bottle of water is not the same as a detergent container, or a plastic cup as a yogurt cup, nor is the bag you get at the supermarket checkout the same as the black, blue or yellow garbage bags that are sold in packs. Yes, it’s all plastic. But it’s not the same plastic – remember that!
Plastic includes a wide range of synthetic and semi-synthetic materials that are used in a huge variety of products. Look around you: it’s almost impossible not to find plastic. It’s a ubiquitous material that makes our lives easier. In some cases, it saves money. In others, less so, it is irreplaceable.
The manufacturing process involves two phases: polymerization and polycondensation. Chemically, plastics are therefore polymer chains, and each type has a different structure and therefore also different properties. In a very broad classification, there are two types of plastic: thermoplastics (their hardness can be altered if the temperature changes) and thermosets (once molded, they neither soften nor harden, but remain stable).