PA6 vs PA66: Nylon Selection Guide for Injection Molding
Published: 2026-06-02
PA6: ring-opening of caprolactam (6 C). PA66: condensation of hexamethylene diamine + adipic acid (6+6 C). PA66 has higher amide density → higher melt point (260 vs 220°C), higher crystallinity. PA66 for high temp/strength; PA6 for better...
PA6: ring-opening of caprolactam (6 C). PA66: condensation of hexamethylene diamine + adipic acid (6+6 C). PA66 has higher amide density → higher melt point (260 vs 220°C), higher crystallinity. PA66 for high temp/strength; PA6 for better surface, lower cost (~10-15% less), better low-temp impact.
Comparison at a Glance
| Tensile Strength | PA6: 80 vs PA66: 85 MPa |
|---|---|
| Melting Point | PA6: 220 vs PA66: 260°C |
| Shrinkage Rate | Both: 1.0-1.5% |
| Flexural Modulus | PA6: 2.8 vs PA66: 3.0 GPa |
| Hdt | PA6: 75 vs PA66: 90°C |
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Ultramid B (PA6) vs Ultramid A (PA66) |
Frequently Asked Questions
Choose PA6 over PA66?
1) ~10-15% cheaper. 2) Better surface finish. 3) Faster cycles (lower melt temp). 4) Better low-temperature impact. If HDT requirement <75°C, PA6 is better economic choice.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org