[Chemistry Class Notes] on Synthetic Polymers Pdf for Exam

Our day-to-day life is filled with so much Chemistry; if we stop and notice each and every phenomenon around us, we will observe so many different things. Most of the things that we touch from handbags to Electronic gadgets contain Polymers. Polymers are basically materials that are made of long repeating chains of molecules. They have their unique properties. A polymer, any category of natural or synthetic compounds made up of very large molecules, called macromolecules, is a duplicate of simple chemical units called monomers. The term polymer refers to an unspecified number of monomer units. When the number of monomers is very large, the compound is sometimes called a high-density polymer. Some natural polymers are composed of a single type of monomer. The most natural and synthetic polymers are, however, composed of two or more different types of monomers; such polymers are known as copolymers.

Types of Polymers

1. Natural Polymers

2. Synthetic Polymers

3. Semi-Synthetic Polymers

In this article, we will mainly focus on the second type, that is Synthetic Polymers.

Classification of Polymers

• Natural Polymers- Natural polymers are polymers that come from nature and exist in natural sources such as plants and animals. Other common examples are protein (found in humans and animals alike), Cellulose and starch (found in plants), or Rubber (which we harvest from a host plant).

• Synthetic Polymers- These are manufactured by industry to meet people’s needs. Some of the most common polymers we use every day are Polyethylene (the bulk plastic we use in packaging) or Nylon Threads (commonly used in our clothing, fishing nets, etc.)

• Semi-Synthetic Polymers- Semi-Synthetic polymers are polymers that are obtained by making changes in natural polymers by making laboratory. These polymers are formed by chemical reactions (in a controlled environment) and are commercially important. Example: Mature Rubber (Sulfur is used to bind polymer chains found in natural rubber) Cellulose acetate (rayon) etc.

Synthetic Polymers

Synthetic polymers are man-made polymers. Polymers are those that consist of duplicate structural units known as monomers. Polyethylene is considered to be one of the simplest polymers, with ethene or ethylene as a monomer unit while the direct polymer is known as high-density polyethylene-HDPE. Synthetic polymers are produced with different types of reactions. Polyethylene, which is synthesized by reproducing ethylene monomers, is an additional polymer. It may have as many as 10,000 monomers wrapped in long chains. Polyethylene is crystalline, translucent, and thermoplastic — that is, it is soft in the heat. It is used for coverings, packaging, molded parts, and the construction of bottles and containers. Its molecules may consist of 50,000 to 200,000 monomers. This compound is used in the textile and textile industry. Some polymers, such as polystyrene, have glass and glow at room temperature, as well as thermoplastic.

What are Synthetic Polymers?

These kinds of polymers can be synthesized or artificially created by man in the lab. They are commercially produced in large quantities to satisfy man’s needs. One of the most common synthetic polymers that we use almost every day includes plastic bags.

Synthetic polymers include most of today’s plastic materials that one can encounter in their day-to-day life such as plastics used in cars, mobile phones, electrical appliances, packaging material, etc. These include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), etc.

Cellulose, proteins, DNA, latex rubber, etc are the naturally occurring polymers. Polythene is the simplest type of synthetic polymer.

Synthetic polymers are usually referred to as “plastics”. The most common types are nylon and polythene. They are mostly formed by the addition of polymers; this process is called addition polymerization. It is also called chain-growth polymers.

There are so many synthetic polymers we use in our everyday life, from nylon used in fabric — Teflon in cooking utensils and Polyvinyl Chloride of PVC in pipes. We also tend to use plastic kits that comprise synthetic polymers such as polyethylene, and tires of vehicles that are manufactured with the help of Buna Rubber.

Types of Synthetic Polymers

There are various synthetic polymers developed to date. Let’s read briefly about a few synthetic polymers used in everyday life-

Nylon

Nylon is a part of the synthetic polymers family and is popularly called polyamides. It was produced on the 28th of February in the year 1935 by a man called Wallace Carothers at DuPont’s research facility. The amide is called the backbone of Nylon, and it is the cause of its hydrophilic nature compared to other polymers. Nylon is a critical factor in producing hydrogen bonding between the molecules.

Low-Density Polyethylene

The Low-Density Polyethylene polymer is the most common kind of synthetic polymer. It is widely used in household products, and it is abbreviated as LDPE. This kind of thermoplastic is usually prepared from monomer ethylene.

Polyvinyl Chloride

Polyvinyl Chloride or PVC is the third-most majorly produced plastic coming after polyethylene and polypropylene. It is mostly used for construction purposes because it is known for being strong and sturdy. It is considered as an alternative instead of iron or steel. Apart from this, PVC is also used in the clothing and electric cable industry. It replaces multiple materials, especially rubber.

Polypropylene

This synthetic polymer is also called polypropene. It is a type of thermoplastic synthetic polymer which is mainly used in a variety of applications such as packaging, labeling, plastics, etc. Polypropylene is also used in many household items like reusable containers, and it is also used in preparing laboratory equipment.

Examples of Major Synthetic Polymers

Uses of Synthetic Polymers

Some common uses of Synthetic Polymers include plastic containers of all shapes and sizes. They are lightweight and economically less expensive than common traditional containers. We use synthetic polymers in our everyday lives from clothing, storage, to construction materials to toys for kids.

Polymers also play a significant role in being a part of the materials that are used in and on the soil to improve aeration which is the phenomenon of creating air spaces between the soil for more permeability of water and minerals. They also promote plant growth and health.

• Nylon is very strong and can be used to make hill climbs, fishing lines, parachutes, and raincoats.

• Sweaters, linings, tracksuits, gloves, and lining boots are made of acrylic.

• Fabric companies use terylene to make tapestry and other garments such as sarees. By mixing it with the natural fiber it is used to make other types of clothing.

• Plastic containers are sturdy and lightweight which is why they are used to make packets of cucumbers, dry food, water, milk, and many other things.

Categories of Synthetic Polymers

Synthetic Polymers are categorized into four different groups such as thermoplastics, thermosets, elastomers, and synthetic fibers.

Thermosets

Thermosets are materials that have enough crosslinking present so that they are stopped from being soluble and melting during heating it. Hence, these materials are tough to recycle and are not promoted for the safety of the surroundings and the welfare of the environment. They can be manipulated into molds by the factor of heat and solidify when cooling. They are materials, especially resins or synthetic plastics, that usually harden permanently after applying heat and pressure.

Thermoplastics

Thermoplastics usually melt on heating and most of the time contain little or no crosslinking. They can be recycled more easily compared to Thermosets, and they can withstand heating and reforming. Linear polymers are examples of thermoplastic materials. They are polymers that can be manipulated into molds by the factor of heat and solidify when cooling.

Elastomers

Elastomers are polymers that possess the elastic properties of natural rubber. They are lightly cross-linked and amorphous. They have a glass transition temperature below room temperature. They can also be envisaged as one very huge molecule of macroscopic size. The forces between the molecules within the polymer chains are comparatively weaker. The crosslinks fully suppress irreversible flow. The chains are very flexible at temperatures above the glass transition, and a small force leads to very large deformation. Hence, proper precautions must be taken while handling elastomers.

Synthetic Fibres

Synthetic fibers are also a very common type of Synthetic polymer. There are man-made textile fibers which include fibers and other materials that are made from natural materials such as rayon, acetate which is a derivative of cellulose, or even regenerated protein fibers from zein. They can also be fully synthetic fibers such as nylon or acrylic fibers.

Advantages and Disadvantages of Synthetic Fibres

Synthetic polymers are an important part of the modern world. They have always made life easier and more convenient in hundreds of different ways, but they also have a downside. They are not free from disadvantages. The raw materials used to produce them can get extinct, and disposing of synthetic polymers is a very difficult and time-consuming task. If proper care is not taken, it can result in environmental degradation.

First, let’s look at the two major advantages.

Synthetic Polymers are very versatile in nature. They are used in multiple fields of life. The methyl 2-cyanopropenoate is the main polymer used in superglue, which is something we use in our day-to-day life. RTV silicone hardens when dried are used to make gaskets for use in cars. Nylon is used in stockings and ropes, and polyester is a major part of the textile industry through which we get a lot of our household items. Desirable Properties are a very important advantage of Synthetic Polymers. They possess good strength, desirable flexibility, resistivity, chemical inertness, and so forth.

Disadvantages of Synthetic Polymers

Many synthetic polymers’ most wanted feature is their chemical inertness, their resistance to various kinds of chemical degradation. This same property, also means they last a long time once they are thrown away which is very harmful to the environment and hence should be taken care of. If these strong polymers are not disposed of properly, it can cause many complications.