definition and properties of polymers,it’s another name for plastics
The simplest definition of a polymer is a useful chemical made of many repeating units . A polymer can be a three dimensional network or two-dimensional network or a one-dimensional network . Each repeating unit is the “-mer” or basic unit with “poly-mer” meaning many repeating units. Repeating units are often made of carbon and hydrogen and sometimes oxygen, nitrogen, sulfur, chlorine, fluorine, phosphorus, and silicon. To make the chain, many links or “-mers” are chemically hooked or polymerized together. Linking countless strips of construction paper together to make paper garlands or hooking together hundreds of paper clips to form chains, or stringing beads helps visualize polymers. Polymers occur in nature and can be made to serve specific needs. Manufactured polymers can be three-dimensional networks that do not melt once formed. Such networks are called THERMOSET polymers. Epoxy resins used in two-part adhesives are thermoset plastics. Manufactured polymers can also be one-dimensional chains that can be melted.These chains are THERMOPLASTIC polymers and are also called LINEAR polymers. Plastic bottles, films, cups, and fibers are thermoplastic plastics.
History of polymers and what its definition:
The chemical manipulation of polymers dates back to the 19th century, although at the time the nature of these species was not understood. The behaviour of polymers was initially rationalised according to the theory proposed by Thomas Graham which considered them as colloidal aggregates of small molecules held together by unknown forces.
Notwithstanding the lack of theoretical knowledge, the potential of polymers to provide innovative, accessible and cheap materials was immediately grasped. The work carried out by Braconnot, Parkes, Ludersdorf and many others on the modification of natural polymers determined many significant advances in the field.Their contributions led to the discovery of materials such as celluloid, galalith, parkesine, rayon, vulcanised rubber and, later, Bakelite: all materials that quickly entered industrial manufacturing processes and reached households as garments components (e.g., fabrics, buttons), crockery and decorative items.
In 1920, Hermann Staudinger published his seminal work “Über Polymerisation”, in which he proposed that polymers were in fact long chains of atoms linked by covalent bonds. His work was debated at length, but eventually it was accepted by the scientific community. Because of this work, Staudinger was awarded the Nobel Prize in 1953.
-Even more-sophisticated technology uses polymers. For example, “the membranes for water desalination, carriers used in controlled drug release and biopolymers for tissue engineering all use polymers,” according to the ACS.
-Electronic and photonic technologies.
-Packaging and containers: films, bottles, food packaging, barrels.
-Insulation: electrical and thermal insulation, spray foams.
-Car parts: tires, bumpers, windshields, windscreen wipers, fuel tanks, car seats.
-Popular polymers for manufacturing include polyethylene and polypropylene. Their molecules can consist of 10,000 to 200,000 monomers.
Characteristics of Polymers:
1-Polymers can be very resistant to chemicals.
2-Polymers can be both thermal and electrical insulators.
3-Generally, polymers are very light in weight with significant degrees of strength.
4-Polymers can be processed in various ways.
5-Polymers are materials with a seemingly limitless range of characteristics and colors.
6-Polymers are usually made of petroleum, but not always.
7-Polymers can be used to make items that have no alternatives from other materials.
Practical uses of polymers:
Polymers are used in five industrial fields, of which three are main, in which polymers are the main component, and they are production areas:
1- Rubber materials and called latex materials in some applications.
2- Synthetic fibers.
3- Plastics are sometimes called resins.
Two non-main areas in which polymers enter with other components are two production areas:
2- Adhesive materials.
Determining the type of use required depends on the natural and chemical characteristics of the polymer.
First: the rubber materials:
The polymers that make up rubber materials have the following structural properties:
1- It consists of very long polymer chains with a very high molecular weight.
2- The necessity of linking these chains to each other with “links” interfaces to give the form of a network in the three dimensions.
3- These polymers have a very low degree of crystallization and are in the unstressed state, meaning that there are no strong “polar or natural” forces of attraction between the sections of the polymer baskets.
4- The glass temperature of these polymers is very much lower than the temperature at which the polymers are operated in different applications.
Second: Synthetic fibers:
The usage properties of polymers that are suitable for being synthetic fibers differ from the properties needed to produce rubber materials.
The polymers needed to make synthetic fibers must have the following structural characteristics:
1- High melting point above 200 degrees, high mechanical properties of tensile strength, etc., of high crystallization hydrogen.
2- The polymer must have a suitable solvent that can isolate the fibers from the polymer solution in this solvent.
3- The polymer bears the tension or pulling process after the spinning process in order to help in the process of organizing the molecules in parallel to increase the chance of internal crystallization. This pulling process takes place at room temperature. And the polymers of most fibers have a glass temperature above room temperature.
4- Polymers suitable for producing synthetic fibers must be linear, have high molecular weight, and contain polar groups along their chain.
Polymers that are suitable for the production of plastic materials are characterized by having intermediate qualities between polymers that are suitable for the production of rubber and polymers that are suitable for the production of industrial fibers. These qualities include:
Among these characteristics are the characteristics of intermolecular attraction in plastic polymers. The degree of attraction between molecules is less than the degree of attraction in the case of synthetic fibers.
As for plastic, it can be a strong material with a high degree of crystallinity that is difficult to break.
Plastic may be a brittle material that is easy to break, in which case the polymer particles that make up the plastic are not amenable to crystallization.
The glass temperature for most of them is above room temperature.
Polymers as one of the applications of chemistry in our lives:
Chemistry is one of the natural sciences known to man since ancient times, and the applications of chemistry in ancient civilizations were associated with mining, paint industry, medicine, tanning leather, dyeing cloth and glass making. They develop theoretical knowledge that can be considered science.
In the seventeenth century, with the division of bodies into raw materials as a result of the research of the world “Boyle”, and “Joseph Priestley” learned about oxygen gas, and then the discovery of the formation of the water molecule by “Henry Cavendish”, all the way to “John Dalton” who developed the modern atomic theory Thus began the era of modern chemistry.
The science of chemistry is the science of matter as it is concerned with the study of the properties of matter, its structure, composition, behavior and interactions, and all the variables that occur in it. The science of chemistry is closely related to the rest of the sciences, such as physics, astronomy, geology and biology.
In the current era, there are many applications of chemistry in all aspects of life. In this article, we will discuss one of the most important applications of chemistry in industry, which is polymers, and it plays a very important role in many different industries because of its unique properties.
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