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What Are Thermosetting Materials? Types, Properties & Characteristics


What Are Thermosetting Materials


Thermosetting materials, also called thermosetting plastics, are polymer materials that form a permanent rigid network structure after heating and chemical curing.

Once fully cured, they cannot be melted, remolded or reshaped by reheating. They will only carbonize under extreme high temperature, instead of softening and flowing like ordinary thermoplastics such as POM and PA.

This stable structure makes thermosetting materials perfect for industrial parts requiring high temperature resistance and dimensional stability.


Common Types of Thermosetting Materials


1. Phenolic Resin (Bakelite)

Phenolic resin is the most widely used and cost-effective thermosetting material. It is our main raw material for gas spring bushings and insulating components.

Filled with wood flour or glass fiber, it features high hardness, good wear resistance and stable dimension. It is suitable for mass industrial production.

Typical applications: Gas spring guide sleeves, insulating washers, electrical switch parts, mechanical wear-resistant structural parts.

It is the best choice when you need wear resistance, insulation and competitive cost.


2. Epoxy Resin

Epoxy resin offers strong adhesion, excellent electrical insulation, low shrinkage and great chemical resistance after curing.

It has high dimensional accuracy and is divided into general grade and high-performance grade.

Applications: Electronic component potting, insulation boards, circuit board bonding, aerospace precision encapsulation, industrial anti-corrosion coatings and sealing parts.

Ideal for projects requiring high bonding strength and precise size control.


3. Thermosetting PU

Different from thermoplastic PU, cured thermosetting PU cannot be remelted.

It combines outstanding wear resistance, shock absorption and impact resistance with moderate elasticity and good recovery after deformation.

Applications: Industrial buffer parts, wear-resistant wheels, sealing parts, automotive shock-absorbing pads and mechanical bushings.

Suitable for dynamic working conditions needing cushioning and anti-wear performance.


4. Unsaturated Polyester Resin

It is cost-effective with simple molding process. It can be compounded with glass fiber to make FRP fiberglass products — lightweight, high strength and weather-resistant.

Applications: Fiberglass housings, industrial pipes, anti-corrosion equipment, mold making and electrical enclosures.

Suitable for non-precision structural parts with cost control requirements.


5. Amino Resin

Including urea-formaldehyde resin and melamine formaldehyde resin.

  • Urea-formaldehyde resin: Low cost, good insulation, widely used for low-voltage electrical shells and wood panel adhesive.

  • Melamine formaldehyde resin: High temperature resistant, flame retardant and non-toxic. Used for melamine tableware, high-temperature electrical shells and fireproof insulating parts.


6. Silicone Resin

Silicone resin is one of the best high-temperature resistant thermosetting materials.
It can work continuously at 200–300°C, with excellent weather resistance, aging resistance, electrical insulation and waterproof sealing performance.
Applications: Motor insulating coating, automotive engine high-temperature parts, electronic sealing components.

Perfect for harsh environments with high heat and humidity.


Core Properties of Thermosetting Materials


1. Excellent High Temperature Resistance

After curing, the stable network structure will not soften, deform or flow under high temperature.

Different grades can withstand 120°C to 300°C, ideal for engine parts, home appliance and heating equipment accessories.


2. High Hardness & Rigidity

Most thermosetting materials such as Bakelite and epoxy resin have high mechanical hardness and compression resistance.

They keep stable shape under long-term load, very suitable for industrial bushings and precision tooling parts.


3. Great Insulation & Flame Retardancy

Naturally good electrical insulation performance. Many types are flame retardant and non-flammable, making them the first choice for electronic and electrical insulating components.


4. Outstanding Dimensional Stability

Low molding shrinkage rate and stable molecular structure.

Not easily affected by temperature and humidity, easy to maintain tight tolerance for precision plastic parts like gas spring bushings.


5. Chemical Corrosion Resistance

Good resistance to oil, acid, alkali and organic solvents.

Aging speed is slow, suitable for harsh industrial working conditions and prolong service life of parts.


6. Cannot Be Remelted & Recycled

Different from thermoplastics, cured thermosetting materials cannot be melted and re-injected.

They can only be crushed as filling material, so production yield control is very important.


Industry Applications

  • Gas spring wear bushings & guide sleeves

  • Electrical insulation structural parts & switch components

  • Automotive high-temperature and oil-resistant plastic parts

  • Household appliance heat-resistant and fireproof parts

  • Mechanical tooling, hardware insulating and wear-resistant parts

  • Precision electronic encapsulation & anti-corrosion equipment


Conclusion


Represented by Bakelite phenolic resin, thermosetting materials cover epoxy resin, thermosetting PU, UF resin and silicone resin.
They share the advantages of high temperature resistance, high hardness, insulation, wear resistance and stable dimension.
They are irreplaceable materials for industrial precision molded parts.
If you need material selection, custom molding and mass production for structural or insulating parts, we can provide professional solution support.