Nylon PA6 properties
Chemical composition
Section titled “Chemical composition”Polyamide 6 (PA6) is a semicrystalline polymer synthesized by ring-opening polymerization of caprolactam, a cyclic monomer with 6 carbon atoms. Its chemical formula is (C₆H₁₁NO)n, with a density of 1.084 g/cm³ at 25 °C.
| Property | Value | Unit |
|---|---|---|
| IUPAC name | Poly(azepan-2-one); poly(hexano-6-lactam) | — |
| Monomer | Caprolactam | — |
| Empirical formula | C₆H₁₁NO | — |
| CAS number | 25038-54-4 | — |
| Density | 1.084 | g/cm³ |
| Autoignition temperature | 434 | °C |
Mechanical properties
Section titled “Mechanical properties”The tensile strength of PA6 in dry state is 40 MPa. The material exhibits an elongation at break of 60% and a flexural modulus of 1 GPa. Moisture absorption significantly modifies its stiffness and toughness.
| Property | Dry state | Conditioned state (50% RH) | Unit |
|---|---|---|---|
| Tensile strength | 40 | 30 | MPa |
| Elongation at break | 60 | 150 | % |
| Yield strain | 4.5 | 20 | % |
| Flexural modulus | 1.0 | 0.5 | GPa |
| Izod notched impact strength | 0.25 | 1.5 | kJ/m |
| Surface hardness | SD75 | — | Shore D |
Physical properties
Section titled “Physical properties”The density of PA6 is 1.084 g/cm³. It exhibits an equilibrium water absorption of 1.5%, the highest among commercial polyamides. The mold shrinkage is 1.2%, lower than that of PA66.
| Property | Value | Unit |
|---|---|---|
| Density | 1.084 | g/cm³ |
| Water absorption (24 h) | 1.5 | % |
| Mold shrinkage | 1.2 | % |
| Oxygen index | 22 | % |
| UL94 flammability rating | HB | — |
Thermal properties
Section titled “Thermal properties”The melting temperature of PA6 is 218.3 °C, with a processing range between 230 and 280 °C. The heat deflection temperature (HDT) at 0.45 MPa reaches 200 °C, while at 1.80 MPa it is 80 °C. The recommended maximum continuous operating temperature is 80 °C.
| Property | Value | Unit |
|---|---|---|
| Melting temperature | 218.3 | °C |
| Melting range for processing | 230 – 280 | °C |
| HDT @ 0.45 MPa | 200 | °C |
| HDT @ 1.80 MPa | 80 | °C |
| Maximum operating temperature | 80 | °C |
| Coefficient of linear expansion | 10 × 10⁻⁵ | /°C |
Electrical properties
Section titled “Electrical properties”The volume resistivity of PA6 is 10¹⁴ Ω·cm. Its dielectric constant at 1 kHz is 8 and the dissipation factor is 0.2. The dielectric strength reaches 25 MV/m, making it suitable for general-purpose electrical insulation components.
| Property | Value | Unit |
|---|---|---|
| Volume resistivity | 10¹⁴ | Ω·cm |
| Dielectric constant at 1 kHz | 8 | — |
| Dissipation factor at 1 kHz | 0.2 | — |
| Dielectric strength | 25 | MV/m |
Chemical resistance
Section titled “Chemical resistance”PA6 exhibits good resistance to hydrocarbons, oils and greases, as well as to dilute alkaline solutions. It is attacked by strong mineral acids, oxidizing agents, and alcohols at elevated temperatures. Prolonged exposure to hot water can cause hydrolytic degradation and loss of mechanical properties.
| Chemical agent | Resistance |
|---|---|
| Hydrocarbons (gasoline, diesel, oils) | Excellent |
| Dilute alkalis | Good |
| Concentrated mineral acids | Poor |
| Strong oxidizing agents | Poor |
| Water at room temperature | Good |
| Hot water (>80 °C) | Limited |
Applications by industry
Section titled “Applications by industry”| Industry | Representative applications |
|---|---|
| Automotive | Fuel tanks, power tool housings, electrical connectors, brackets, clamps, gears |
| Consumer goods | Combs, kitchen utensils, closures, appliance components |
| Industrial | Gears, cams, rollers, bearings, bolts and nuts |
| Electrical and electronics | Connectors, coil formers, switch housings, insulators |
| Textile | Fibers for carpets, hosiery, industrial fabrics, ropes (strength of 880 lbf for 4.8 mm diameter) |
| Sports and recreation | Sports equipment components, bindings, fishing reels |
Comparison with similar materials
Section titled “Comparison with similar materials”| Property | PA6 | PA66 | POM (Acetal) | PBT |
|---|---|---|---|---|
| Density (g/cm³) | 1.084 | 1.14 | 1.41 | 1.31 |
| Tensile strength (MPa) | 40 | 55 | 60 | 50 |
| Flexural modulus (GPa) | 1.0 | 1.5 | 2.5 | 2.2 |
| Water absorption (%) | 1.5 | 1.2 | 0.2 | 0.1 |
| Melting temperature (°C) | 218 | 260 | 175 | 225 |
| HDT @ 1.80 MPa (°C) | 80 | 90 | 95 | 60 |
| Izod impact strength (kJ/m) | 0.25 | 0.30 | 0.20 | 0.15 |
| Mold shrinkage (%) | 1.2 | 1.5 | 1.8 | 1.5 |
Processing
Section titled “Processing”| Parameter | Value | Unit |
|---|---|---|
| Mold temperature | 40 – 60 | °C |
| Melt temperature | 230 – 280 | °C |
| Pre-drying | 3 h at 95 °C | — |
| Mold shrinkage | 1.2 | % |
| Reaction injection molding (RIM) | Suitable | — |
| Extrusion | Suitable for profiles, sheets, and fiber | — |
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the density of PA6?
Section titled “What is the density of PA6?”The density of PA6 is 1.084 g/cm³ at room temperature, lower than that of PA66 (1.14 g/cm³).
What maximum operating temperature does PA6 withstand?
Section titled “What maximum operating temperature does PA6 withstand?”The recommended maximum continuous operating temperature for PA6 is 80 °C, with a melting temperature of 218.3 °C.
How much water does PA6 absorb compared to other polymers?
Section titled “How much water does PA6 absorb compared to other polymers?”PA6 has a water absorption of 1.5% in 24 hours, the highest among commercial polyamides, compared to 1.2% for PA66 or 0.2% for POM.
What is the tensile strength of PA6 in dry state?
Section titled “What is the tensile strength of PA6 in dry state?”The tensile strength of PA6 in dry state is 40 MPa, which decreases to approximately 30 MPa after conditioning in humidity.
What flammability rating does PA6 have according to UL94?
Section titled “What flammability rating does PA6 have according to UL94?”Unmodified PA6 has a UL94 HB rating, with an oxygen index of 22%.
At what temperature is PA6 processed by injection molding?
Section titled “At what temperature is PA6 processed by injection molding?”PA6 is processed by injection molding with a melt temperature between 230 and 280 °C and a mold temperature between 40 and 60 °C.
References
Section titled “References”- azom.com: https://www.azom.com/article.aspx?ArticleID=442
- engineeringtoolbox.com: https://www.engineeringtoolbox.com/nylon-rope-strength-d_1513.html
- steelnumber.com: https://www.steelnumber.com/en/search_form_eu.php