Difference Between Plastic and Rubber

Main Difference – Plastic vs Rubber

Both plastic and rubber are polymers. A polymer is a macromolecule that is made out of many repeating units. Each repeating unit represents the monomer that is used to build up the polymer. Some polymers are synthetic whereas other polymers are naturally occurring compounds. Plastic is a synthetic polymer whereas rubber is found as a natural polymer. This is the main difference between plastic and rubber. Both these compounds are very useful in the production of different items.

Key Areas Covered

1. What is Plastic
      –  Definition, Properties, Different Products
2. What is Rubber
      – Definition, Properties, Different Products
3. What is the Difference Between Plastic and Rubber
      – Comparison of Key Differences

Key Term: Monomer, Natural Rubber, Plastic, Polymer, Rubber, Synthetic Polymer, Synthetic Rubber

What is Plastic

Plastic is a polymer material that has the ability to be molded and shaped by the application of heat and pressure. This property is known as plasticity. It is a synthetic polymer. The malleability of plastic allows it to be molded into different shapes.

Apart from that, the light weight of plastic is also a good reason for it to be used in the production of different equipment. Plastic has a low density, poor electrical conductivity, transparency, toughness, etc. Plastics are very stable with a slower rate of degradation.

There is a wide variety of plastic polymers. These plastics can be categorized according to several different parameters. We can classify plastics according to chemical properties, physical properties, chemical structure, method of synthesis, etc.

Some commercially important plastics include polyethylene, polypropylene, polystyrene, PET, PTEF, etc. In the production processes of these plastic varieties, some chemicals are added to the reactions mixtures. These chemical compounds include stabilizers (to give a long shelf life to the polymer), fillers (to improve performance), plasticizer (to improve rheology), etc. Sometimes, colorants are also added in order to obtain eye-catching colors in the end product. These externally added compounds are called additives.

Figure 1: Plastic Bottle Caps

There are many applications of plastics in almost all fields including medicine, textile industry, food and beverages (as packaging material).

What is Rubber

Rubber is an elastic material that is either obtained from rubber plants or synthesized using petroleum oil. Therefore, there are two types of rubber as natural rubber and synthetic rubber. Rubber is very famous in industries due to its elasticity, toughness, etc. Rubber is used for the production of many different products.

Natural rubber consists of polymers of isoprene and water along with some other compounds. The major component of natural rubber is polyisoprene. It is the polymer material (elastomer) present in natural rubber. Natural rubber is obtained from rubber tree latex. This latex is milky and sticky. It is a suspension. This latex can be obtained from the parts near the bark of the tree.

Natural rubber is susceptible to vulcanization due to the presence of a double bond in the backbone of the polymer. Vulcanization is the process of forming crosslinks between polymer chains using sulfur as the crosslinking reagent. The vulcanized rubber is more stiff, rigid and durable than that of natural rubber.

Figure 2: The Structure of Polyisoprene in Natural Rubber

Synthetic rubber is produced from petroleum oil or natural gases. Synthetic rubbers are made in chemical plants using petrochemicals as their starting point. For example, the reaction of acetylene and hydrochloric acid gives polychloroprene, a type of synthetic rubber.

Figure 3: Rubber Bands

There is a wide variety of products obtained from rubber. Some examples include shoes, vehicle tires, waterproof clothes, balloons, protective gloves, and many other things. 

Difference Between Plastic and Rubber

Definition

Plastic: Plastic is a polymer material that has the ability to be molded and shaped by the application of heat and pressure.

Rubber:  Rubber is an elastic material that is either obtained from rubber plants or synthesized using petroleum oil.

Unique Features

Plastic:  Plastic has plasticity.

Rubber:  Rubber has elasticity.

Occurrence

Plastic: Plastic is obtained from industrial methods.

Rubber: Rubber can be obtained from both industrial methods and from natural sources.

Production

Plastic:  Plastic is produced by taking crude oil as the starting material.

Rubber: Rubber is naturally produced in rubber trees as rubber latex or can be produced industrially from petroleum oil and natural gases.  

Toxicity

Plastic: Plastic is less toxic.

Rubber: Rubber is more toxic.

Conclusion

Plastic and rubber are used in the manufacturing of a variety of products that we need in our daily life. Both these compounds are polymer materials. They have unique properties depending on their chemical structures. The main difference between plastic and rubber is that plastic is essentially a synthetic polymer whereas rubber can be found as a natural polymer or can be produced as a synthetic polymer.

References:

1. Gent, Alan N. “Rubber.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 23 May 2016, Available here.
2. “Natural rubber.” Wikipedia, Wikimedia Foundation, 18 Oct. 2017, Available here.
3. “Plastic.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 27 June 2017, Available here.

Image Courtesy:

1. “528789” (Public Domain) via Pixabay
2. “Cis Polyisoprene, Natural rubber” By Prabhachatterji at Malayalam Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
3. “350095” (Public Domain) via Pixabay