Thermoplastics vs thermosets: what is the difference?
Thermoplastics are plastics that can be melted and reshaped multiple times whilst retaining their material properties. Thermosets undergo a chemical reaction when heated, which permanently cures the material. They can only be processed once and cannot be remelted. This single difference has major implications for recyclability, production techniques and areas of application.
Comparison of key characteristics
| Characteristic | Thermoplastic | Thermoset |
|---|---|---|
| Remeltable | Yes, several times | No, cures once |
| Recyclability | Good, raw material reusable | Limited |
| Temperature resistance | Limited at high temperatures | High, stable at high temperatures |
| Manufacturing technique | Injection moulding, extrusion | Casting, pressing, laminating |
| Applications | Crates, housings, packaging | Printed circuit boards, car parts, composites |
Why are thermoplastics remeltable?
Thermoplastics consist of long polymer chains that are not chemically bonded to one another. When heated, the weak bonding forces between these chains break and the material becomes liquid. Once cooled, it solidifies again into the desired shape, without the chains undergoing any chemical changes.
This reversibility makes thermoplastic material ideal for injection moulding. Production offcuts can be regrinded and re-injected. This aligns with Didak Injection’s zero-waste approach: internal production waste is fully reused as raw material. Of the 25,000 tonnes of raw materials used annually, 7,000 tonnes are recycled material.
Why do thermosets cure permanently?
In thermosets, the molecules react with one another during heating and form three-dimensional networks, also known as cross-links. These chemical bonds are irreversible: the material remains hard, even when reheated. This makes thermosets extremely suitable for applications where thermal stability is essential, such as printed circuit boards, brake components or structural composites.
Outside these niche applications, the limited recyclability is becoming an increasingly significant factor, particularly now that the PPWR legislation imposes specific recycling requirements on packaging in circulation within the EU.
Which thermoplastics are most commonly used in injection moulding?
Polypropylene (PP) and polyethylene (PE, HDPE) form the backbone of the injection moulding industry. They combine good mechanical properties with ease of processing, food-contact approval and excellent recyclability. Didak Injection’s crates are largely made from these materials.
For more demanding applications, engineering thermoplastics such as ABS, polyamide (PA) and polycarbonate (PC) are available. They offer better stiffness, impact resistance or temperature resistance. The choice depends on the mechanical requirements, the chemical environment and the desired surface finish. Didak Injection continuously tests new additives and combinations to improve your product’s performance without compromising on quality or sustainability.
When should you choose which material?
Opt for a thermoplastic if recyclability, production efficiency and injection moulding as a process are key considerations. This applies to the vast majority of applications in packaging, logistics, consumer products and industrial components.
A thermoset is the better choice if the product needs to withstand high temperatures, aggressive chemicals or extreme mechanical stress over the long term, and recyclability is not a decisive criterion. Examples include electrical insulators or structural composites in the aerospace industry.
Which material is best suited to your product? Didak Injection is here to help.
