
When selecting nylon materials for engineering applications, PA6 and PA66 are the two most common choices. While both belong to the polyamide family, their different molecular structures lead to distinct property profiles that can significantly impact your product’s performance.
Molecular Structure: The Key Difference
The fundamental difference between PA6 and PA66 lies in their chemical structure. PA6 (Polycaprolactam) is made from a single monomer—caprolactam—with six carbon atoms per repeat unit. PA66 (Polyhexamethylene adipamide) is made from two monomers—hexamethylene diamine and adipic acid—each contributing six carbons to the repeat unit.
This structural difference affects crystallinity, melting point, and ultimately the material’s mechanical and thermal properties.
機械的特性の比較
| プロパティ | PA6 | PA66 |
|---|---|---|
| 引張強さ (MPa) | 70-85 | 80-95 |
| 破断伸度(%) | 50-150 | 30-60 |
| 曲げ弾性率 (GPa) | 2.5-3.0 | 2.8-3.3 |
| Notched Izod Impact (kJ/m²) | 5-15 | 4-8 |

Thermal Properties
PA66 has a higher melting point (approximately 260°C vs 220°C for PA6) and better heat deflection temperature.
連続使用温度
- PA6: 80-100°C
- PA66: 100-120°C
水分吸収
Both PA6 and PA66 are hygroscopic materials, meaning they absorb moisture from the environment. However, PA6 typically absorbs moisture faster due to its lower crystallinity.

Processing Differences
PA6 has a wider processing window and lower processing temperature requirements, making it easier to mold. PA66 requires more precise temperature control and higher processing temperatures.
Processing Parameters
- PA6 Melt Temperature: 230-280°C
- PA66 Melt Temperature: 270-300°C
- PA6 Mold Temperature: 40-80°C
- PA66 Mold Temperature: 60-100°C
Cost Considerations

PA6 is typically 10-20% less expensive than PA66 on a per-kilogram basis.
Application Recommendations
Choose PA6 When:
- Impact resistance is critical
- Cost sensitivity is high
- Processability and cycle time matter
- Parts will not be exposed to high temperatures
Choose PA66 When:
- High temperature resistance is required
- Stiffness and strength are priorities
- Dimensional stability under load matters
- Parts will be used in demanding environments
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を超える。 300台のCNCマシン, を生産している。 毎日10,000個 という厳しい公差で ±0.005mm. .我々は受け入れる 1個からのMOQ, 納期は以下の通り。 24時間~15日間. 24時間以内にお見積もりいたします。.
よくあるご質問
How do you know whether PA6 vs PA66: Which Nylon Grade Is Right for Your Application? fits a part?
PA6 vs PA66: Which Nylon Grade Is Right for Your Application? fits a part when its load capacity, temperature range, moisture exposure, wear behavior, and processing method match the real service conditions.
What properties should be checked for PA6 vs PA66: Which Nylon Grade Is Right for Your Application??
Check strength, stiffness, impact resistance, heat resistance, moisture absorption, dimensional stability, friction, wear, and chemical compatibility.
What is the biggest selection risk for PA6 vs PA66: Which Nylon Grade Is Right for Your Application??
The biggest risk is choosing from a datasheet value without considering actual environment, processing method, part geometry, and long-term use.
When should PA6 vs PA66: Which Nylon Grade Is Right for Your Application? be tested before production?
Testing is recommended when the part faces load, heat, chemicals, moisture, tight tolerances, regulatory requirements, or a new operating environment.


