Thermoplastics

Thermosetting plastics

Thermosetting Plastics are made up of lines of molecules which are heavily cross-linked.

It creates a rigid molecular structure. They may be heated the first time and shaped but they become permanently stiff and solid. They cannot be reshaped again.

Cross-linked molecules

The molecules of thermosetting plastics are heavily cross-linked. They form a rigid molecular structure.

Whereas in thermoplastics the molecules sit end to end, the molecules in thermoplastics sit end-to-end and side-by-side.

Although they soften when heated the first time, which allows them to be shaped they become permanently stiff and solid and cannot be reshaped.

Thermoplastics remain rigid and non-flexible even at high temperatures. Polyester resin and urea formaldehyde are examples of thermosetting plastics.