Plastic Materials

Description:

Plastic materials are high molecular weight organic materials that can be shaped into any preferred form by the application of heat and pressure in the presence of a catalyst. Originally, plastics were discovered and then developed based on trial and error method. The present era is referred to as the plastic age because of the extensive usage of polymeric material across a variety of applications.

Types of Plastic materials:

Based on the usage, plastic materials can be divided into the following two categories:

• General-purpose plastic materials (commodity) - General-purpose plastics have low to medium mechanical properties. They account for about 80-85% of total polymer production. Polyethylene and polypropylene are the most popular types of general purpose plastic materials.
• Engineering plastic materials or high performance plastic materials - Engineering plastics are a group of materials obtained from high polymer resins. They possess high mechanical strength, toughness, and higher use temperature. They are mainly used in load bearing applications, generally to replace conventional materials like metal, wood, glass, and ceramics. Engineering plastics act as substitutes for metals and they can also be used along with metals.

Properties:

The common properties of plastic materials are listed below:

General purpose plastic materials:

• They are mostly crystalline with low glass transition temperature. Otherwise they are glossy or amorphous polymers
• They have low to medium mechanical properties

Engineering plastic materials:

• High load bearing characteristics
• High abrasion resistance
• Very good rigidity
• High mechanical strength
• Lightweight

Advantages:

Plastic materials offer the following advantages:

• They are light in weight
• They possess low melting point
• They can be easily molded and have excellent finishing
• They possess very good strength and toughness
• They possess good shock absorption capacity
• They are corrosion resistant and chemically inert
• They have low co-efficient of thermal expansion and possess good thermal and electrical insulating property
• They have very good water-resistance and possess good adhesiveness

Applications:

General-purpose plastics are used in the production of commodity items. Engineering plastics find applications in demanding areas like automobiles, defense, electrical and electronics, telecommunications, textiles, satellite, robots, computer components, etc.