Types of Plastic
Plastic Classification Tree
Classification of plastics
When plastics are classified by chemical structure, there are two generally recognized classes of plastic materials: Thermosets, having cross-linked molecular chains, and Thermoplastics, which are made up of linear molecular chains. In addition, thermoplastic polymers can also be classified into two types: Crystalline and Amorphous.
Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be molded again and again.
Pros: Highly Recyclable
Cons: Poor Heat Resistance
Thermosets can melt and take shape once; after they have solidified, they stay solid. In the thermosetting process, a chemical reaction occurs that is irreversible.
Pros: Good Heat Resistance and Weather Resistance
Cons: Difficult to be Recycled
Crystalline Plastics
Crystalline structures are generally very ordered, which is what gives them strength and rigidity. A crystalline polymer, where the molecular chains are largely locked in place against one another, is similar. Apply a load and it will break rather than bend.
Features: Have a Sharp Melting Point, Opaque, Higher Shrinkage, Good Chemical Resistance, Higher Mechanical Properties.
Amorphous Plastics
Rather than being rigid, the random molecular jumble lets the chains move across each other when the polymer is pushed or pulled. In short, amorphous polymers have flexibility and elasticity.
Features: Do not have a Sharp Melting Point, Transparent, Lower Shrinkage, Poor Chemical Resistance, Lower Mechanical Properties