Material Introduction: Polyamide or Nylon is the major engineering and high performance thermaplastic class because of its good balance of properties. Polyamides contain repeating amide linkages i.e. –CO-NH–. It is formed by condensing identical units, copolymers for different units.
Polyamides (or Nylon) are made from polycondensation of diacid with a diamine or by ring-opening polymerization of lactams with 6, 11 or 12 carbon atoms.
- The monomers may be aliphatic, semi-aromatic or aromatic (aramids)
- They may be amorphous, semi-crystalline and of greater or lesser crystallinity
Aromatic polyamides (or Aramids) are obtained from polycondensation of terephthalic acid with diamines. PA 6-3-T is one of the common examples of aromatic polyamide which is an amorphous transparent in nature. The materials can be processed at 280-300°C. Aramids are expensive, have better dimensional stability, flame and heat resistance and higher strength as compared to aliphatic polyamides.
Polyamides exhibit high temperature and electrical resistance. Thanks to their crystalline structure, they also show excellent chemical resistance. They have very good mechanical and barrier properties. In addition, these materials can easily be flame retarded. Polyamides became the first truly synthetic fiber to be commercialized.
Properties Comparison: PA6 Vs PA66
Compare all relevant properties of PA6 and PA66 before selecting the right engineering thermoplastic for a particular application. From physical properties, dimensional stability, electrical performances to fire and thermal properties, find out every possible attribute with its values here.
| Property | PA6 | PA66 |
| Dimensional Stability | ||
| Coefficient of Linear Thermal Expansion | 5 - 12 x 10-5 /°C | 5 - 14 x 10-5 /°C |
| Shrinkage | 0.5 - 1.5 % | 0.7 - 3 % |
| Water Absorption 24 hours | 1.6 - 1.9 % | 1 - 3 % |
| Electrical Properties | ||
| Arc Resistance | 118 - 125 sec | 130 - 140 sec |
| Dielectric Constant | 4 - 5 | 4 - 5 |
| Dielectric Strength | 10 - 20 kV/mm | 20 - 30 kV/mm |
| Dissipation Factor | 100 - 600 x 10-4 | 100 - 400 x 10-4 |
| Volume Resistivity | 14 x 1015 Ohm.cm | 14 x 1015 Ohm.cm |
| Fire Performances | ||
| Fire Resistance (LOI) | 23 - 26 % | 21 - 27 % |
| Flammability UL94 | HB | HB |
| Mechanical Properties | ||
| Elongation at Break | 200 - 300 % | 150 - 300 % |
| Elongation at Yield | 3.4 - 140 % | 3.4 - 30 % |
| Flexibility (Flexural Modulus) | 0.8 - 2 GPa | 0.8 - 3 GPa |
| Hardness Rockwell M | 30 - 80 | 30 - 80 |
| Hardness Shore D | 80 - 95 | 80 - 95 |
| Stiffness (Flexural Modulus) | 0.8 - 2 GPa | 0.8 - 3 GPa |
| Strength at Break (Tensile) | 50 - 95 MPa | 50 - 95 MPa |
| Strength at Yield (Tensile) | 50 - 90 MPa | 45 - 85 MPa |
| Toughness (Notched Izod Impact at Room Temperature) | 50 - 160 J/m | 50 - 1150 J/m |
| Toughness at Low Temperature (Notched Izod Impact at Low Temperature) | 16 - 210 J/m | 27 - 35 J/m |
| Young Modulus | 0.8 - 2GPa | 1 - 3.5 GPa |
| Optical Properties | ||
| Gloss | 130 - 145 % | 65 - 150 % |
| Physical Properties | ||
| Density | 1.12 - 1.14 g/cm3 | 1.13 - 1.15 g/cm3 |
| Glass Transition Temperature | 60 °C | 55 - 58 °C |
| Radiation Resistance | ||
| Gamma Radiation Resistance | Fair | Fair |
| UV Light Resistance | Fair | Poor |
| Service Temperature | ||
| HDT @0.46 Mpa (67 psi) | 150 - 190 °C | 180 - 240 °C |
| HDT @1.8 Mpa (264 psi) | 60 - 80 °C | 65 - 105 °C |
| Max Continuous Service Temperature | 80-120 °C | 80 - 140 °C |
| Min Continuous Service Temperature | -40 to -20 °C | -80 to -65 °C |
| Others | ||
| Sterilization Resistance (Repeated) | Poor | Poor |
| Thermal Insulation (Thermal Conductivity) | 0.24 W/m.K | 0.25 W/m.K |