Molds are made of thermoplastics and thermosetting plastics, which are two different types of polymers. Here is a thorough guide to the differences
F) Difference Between Thermoplastics & Thermo-Setting Plastics
Thermoplastic vs. Thermoset Wire and Cable Materials
Difference Between Thermoplastic And Thermosetting Polymer?-Class Series
32. Why are electric switches, plugs and sockets made of
Powder Coating: Thermoplastics vs. Thermosetting - Powder Coat
Solved The difference between thermoplastic and
Differences between Thermoplastic and Thermosetting Plastic
Thermoplastic and Thermosetting Plastic - Uses and Examples
The Difference Between Thermoplastic and Thermosetting Plastic, PDF, Thermoplastic