Polyamide 6.6 (PA6.6) is similar to PA6, but thanks to its molecular structure it absorbs less moisture and has a higher melting point at approximately 260°C. This results in a material with slightly better thermal properties, low impact resistance and higher strength and modulus. Thanks to the excellent mechanical properties and exemplary resistance to wear and chemical attacks, this is one of the most frequently used engineering thermoplastics. If a slightly higher impact resistance is required, KIK uses special types of polyamide 6.6.
PA6.6 absorbs approximately 2.5% moisture at 23°C/50% RH and 8.5% when saturated in water. PA6.6 possesses excellent resistance to oils, greases and most cleaning agents. It cannot withstand acids and alkalis.
A frequently used variant of PA6.6 is High Impact Polyamide 6.6 HI (PA6.6 HI).
Like PA6.6, PA6.6 HI is frequently used in a variety of applications that require high impact resistance at low temperatures, or where extreme shock loads occur. This explains why this material is frequently chosen for sports articles like ski binders, shock absorbing soles and parts of racing cycles. The same applies to products that need to be stretchable in dry conditions, like click-on casings and cable binders.
Polyamides absorb moisture, which can result in minor changes to dimensions, while the material becomes less rigid due to moisture and obtains greater impact resistance.
Depending on the load, temperatures of up to 140 to 160°C are permissible, but above that level ageing occurs quickly. By adding certain minerals or glass fibre, a wide spectrum of types becomes available, each with its own particular mechanical specifications.
PA6.6 possesses excellent electrical properties, but as with all polyamides, they depend greatly on temperature and moisture.