What is the difference between thermosets and thermoplastics?
Due to their lower melting points, thermoplastic plastics are highly suitable for applications involving recycled materials. In contrast, thermosetting plastics can withstand high temperatures without deformation, making them more durable.
From an aesthetic perspective, thermoplastic plastics are considered superior to thermosetting polymers, but thermosetting materials are still regarded as more aesthetically pleasing compared to alternatives such as metals. These materials allow for in-mold painting or coating, including the direct application of coatings to the mold before injecting thermosetting polymers. This technique provides better material adhesion, even in adverse weather conditions, and prevents cracking, breaking, or peeling.
Thermosetting Plastics
Thermosetting plastics, also known as thermosetting resins or thermosetting polymers, are typically liquid at room temperature and then harden when heated or exposed to specific chemical agents. They are often produced using processes like Reaction Injection Molding (RIM) or Resin Transfer Molding (RTM) and form permanent chemical bonds during the curing process. These chemical bonds between monomer chains within the material, known as crosslinks, anchor the molecules in place and alter the material’s properties, preventing it from melting and reverting to a liquid state. Once heated, thermosetting plastics take on a specific shape, but overheating can cause them to degrade rather than revert to a fluid phase.
Thermosetting plastics are well-suited for applications that require heat resistance and chemical resistance due to their higher structural integrity. Common uses for thermosetting materials include electronic enclosures, electrical components, and chemical processing equipment. Common thermosetting materials include epoxy resins, polyimides, and phenolic resins, which can withstand deformation and impact and are often used in composite materials.
Thermosetting plastics and thermoplastic plastics are both polymers, but they behave differently when exposed to heat. Thermoplastic plastics melt upon heating after they have solidified, whereas thermosetting plastics, once cured, maintain their shape and remain in a solid state when heated.
Due to their lower melting points, thermoplastic plastics are highly suitable for applications involving recycled materials. In contrast, thermosetting plastics can withstand high temperatures without deformation, making them more durable.
From an aesthetic perspective, thermoplastic plastics are considered superior to thermosetting polymers, but thermosetting materials are still regarded as more aesthetically pleasing compared to alternatives such as metals. These materials allow for in-mold painting or coating, including the direct application of coatings to the mold before injecting thermosetting polymers. This technique provides better material adhesion, even in adverse weather conditions, and prevents cracking, breaking, or peeling.
Advantages:
Thermosetting plastics offer a wide range of advantages:
1. Can be molded with various tolerances.
2. Allow for flexible product design.
3. Improved structural integrity by altering wall thickness.
4. Typically cheaper than parts manufactured from metal.
5. Excellent electrical insulation properties.
6. Excellent heat resistance at high temperatures.
7. Corrosion resistance.
8. Strong dimensional stability.
9. Low thermal conductivity.
10. Lower installation and mold costs compared to thermoplastic plastics.
11. High strength-to-weight ratio.
12. Waterproof properties.
13. Available in a variety of colors and surface finishes.
Disadvantages:
Despite these numerous advantages, thermosetting polymers still have some disadvantages:
Cannot be reshaped or reprocessed.
Cannot be recycled.
Why are thermosets harder than thermoplastics?
Thermoset plastics are harder than thermoplastics due to the three-dimensional network of bonds, or crosslinks, that are created during the manufacturing process. Because they maintain their shape as strong covalent bonds between polymer chains, thermosets are more suited to high temperature applications too. The higher the crosslink density, the better they are able to resist heat degradation and chemical attack. Higher crosslink density also improves the mechanical strength and hardness of these materials, although this can lead to brittleness.
Conclusion
With variations in material properties, recyclability and more, there are a range of differences between thermoset and thermoplastics. This makes them suitable for different applications depending on factors such as required hardness and temperature resistance.
While thermoplastics are not as suited to higher temperature applications as thermosets, they can be recycled and re-used whereas thermosets cannot be melted and reshaped in the same manner.
