Thermoplastics vs Thermosetting Plastics
Plastics are divided into two groups depending on how it reacts to heat. Thermoplastics can be repeatedly softened by heating and hardened by cooling.Thermosetting plastics, however, harden permanently after being heated once.
When you heat thermoplastics, the molecules do not chemically bond with each other. Instead, thermoplastic chains are held together by van der waal forces, weak attractions between molecules. Visually speaking, thermoplastic chains are clumped together like a ball of tangled yarn.
Thermoplastics are 100% recyclable. In ideal situations, thermoplastics can be repeatedly melted and remolded into new products.
Thermosetting plastic properties:
Thermosetting plastic molecules, on the other hand, form permanent chemical bonds or cross links with each other once heated. Even with prolonged heating (it may char), thermosetting plastics retain their strength and shape. This makes thermosetting plastics ideal for producing heat resistant products such as insulation parts, car parts, etc.
Examples of thermosetting plastics include phenolic resins, amino resins, polyester resins, silicon resins, epoxy resins, and polyurethanes.
Thermosetting plastic recycling
Although thermosetting plastics cannot be melted into new products, they can still be reused for other applications. An excellent example is polyurethane foam. Flexible polyurethane foams are commonly shredded into small flakes and re-manufactured into carpet underpayment.