POM vs. Polycarbonate

Attribute	POM	Polycarbonate
Chemical Structure	Linear	Linear
Strength	High	High
Flexibility	Low	High
Transparency	Opaque	Transparent
Temperature Resistance	High	High

Introduction

When it comes to engineering plastics, POM (Polyoxymethylene) and Polycarbonate are two popular choices due to their unique properties and applications. Both materials have their own set of advantages and disadvantages, making them suitable for different uses in various industries. In this article, we will compare the attributes of POM and Polycarbonate to help you understand which material may be more suitable for your specific needs.

Chemical Structure

POM, also known as acetal or polyacetal, is a semi-crystalline thermoplastic polymer with a repeating unit of -CH2O-. It is a highly crystalline material with excellent mechanical properties, such as high stiffness, low friction, and good wear resistance. On the other hand, Polycarbonate is a transparent amorphous thermoplastic polymer with a repeating unit of -C6H4- (OCOCH2)2. It is known for its high impact strength, heat resistance, and optical clarity.

Mechanical Properties

When it comes to mechanical properties, POM is known for its high stiffness, excellent dimensional stability, and low coefficient of friction. It has a high tensile strength and good impact resistance, making it suitable for applications that require high precision and durability. Polycarbonate, on the other hand, is known for its high impact strength, toughness, and flexibility. It can withstand high impact loads without breaking, making it ideal for applications that require impact resistance.

Thermal Properties

Both POM and Polycarbonate have good thermal properties, but they differ in their heat resistance and temperature range. POM has a higher heat deflection temperature (HDT) compared to Polycarbonate, making it more suitable for high-temperature applications. However, Polycarbonate has a higher continuous use temperature and better resistance to creep at elevated temperatures. It can withstand temperatures up to 140°C, while POM has a maximum temperature of around 100°C.

Chemical Resistance

When it comes to chemical resistance, POM is more resistant to solvents, fuels, and oils compared to Polycarbonate. It has good resistance to a wide range of chemicals, making it suitable for applications that require exposure to harsh chemicals. On the other hand, Polycarbonate is more susceptible to chemical attack and may degrade when exposed to certain chemicals, such as alkalis and acids. It is important to consider the chemical environment when choosing between POM and Polycarbonate for your application.

Processing

Both POM and Polycarbonate can be easily processed using common methods such as injection molding, extrusion, and machining. However, POM has better machinability compared to Polycarbonate due to its low friction and excellent dimensional stability. It can be easily machined to tight tolerances and complex shapes, making it suitable for applications that require high precision. Polycarbonate, on the other hand, may require special processing techniques due to its amorphous nature and tendency to warp during processing.

Applications

POM is commonly used in applications that require high stiffness, low friction, and excellent dimensional stability, such as gears, bearings, and automotive components. Its high wear resistance and self-lubricating properties make it ideal for applications that require high precision and durability. Polycarbonate, on the other hand, is commonly used in applications that require high impact strength, optical clarity, and heat resistance, such as safety goggles, electronic housings, and automotive headlamps. Its transparency and impact resistance make it suitable for applications that require visibility and protection.

Conclusion

In conclusion, POM and Polycarbonate are two versatile engineering plastics with unique properties and applications. While POM is known for its high stiffness, low friction, and excellent dimensional stability, Polycarbonate is known for its high impact strength, optical clarity, and heat resistance. The choice between POM and Polycarbonate will depend on your specific requirements and the application in which the material will be used. Consider factors such as mechanical properties, thermal properties, chemical resistance, processing, and applications when choosing between POM and Polycarbonate for your project.