Which has better toughness, Nylon 6 (PA6) or Nylon 66 (PA6)?

 

Nylon 6 (polyamide 6, PA6) and Nylon 66 (polyamide 66, PA66) are two of the most common types of polyamides, each with its own unique performance advantages. Toughness generally refers to a material's resistance to fracture; it is less prone to breakage when subjected to external impact.

 

Nylon 6 (PA6) is generally considered to have better toughness than Nylon 66 (PA66), especially in low-temperature environments. The molecular structure of PA6 results in slightly higher hygroscopicity than PA66, meaning that PA6's toughness further increases after absorbing moisture, as the presence of moisture makes the material more flexible. However, this also makes PA6 less dimensionally stable than PA66, potentially making it less suitable for applications with strict dimensional requirements.

Nylon 66 has better thermal stability and higher mechanical properties, maintaining good strength and rigidity at higher temperatures. Although PA66's inherent toughness is slightly inferior to PA6, it is still a material with good toughness and is generally suitable for applications requiring high strength and high dimensional stability.

 

When selecting suitable nylon materials, the specific environmental conditions, load conditions, and cost factors of the application should be considered. Toughness requirements are not the only criterion for evaluating polyamide applications. Other performance indicators such as strength, rigidity, thermal stability, abrasion resistance, flame retardancy, and chemical resistance should also be determined on a case-by-case basis.

 

Of course, the toughness and abrasion resistance of PA6 or PA66 can also be increased through modification. For information on additives that increase abrasion resistance, please refer to: What are the abrasion-resistant additives for nylon?