Comprehensive technical data on nylon/PA material properties — thermal, mechanical, chemical resistance, electrical, and comparison tables across grades.
Overview of Nylon Material Properties
Nylon (polyamide) materials occupy a unique position in engineering thermoplastics: they offer the highest combination of strength, toughness, and wear resistance among non-reinforced plastics, while remaining processable on standard injection molding and extrusion equipment. This technical reference compiles the key properties that engineers, designers, and procurement specialists need when evaluating nylon for specific applications.
All data in this reference applies to conditioned material (23°C, 50% RH) unless otherwise noted. Moisture content significantly affects mechanical properties — dry-as-molded values can be 20-40% higher than conditioned values for unfilled nylon.
Mechanical Properties by Nylon Grade
Tensile Properties:
| Property | PA6 | PA66 | PA46 | PA12 | PA6-GF30 | PA66-GF30 |
|---|---|---|---|---|---|---|
| Tensile Strength (MPa) | 80 | 82 | 90 | 55 | 170 | 185 |
| Elongation at Break (%) | 150 | 60 | 45 | 200 | 3 | 3 |
| Tensile Modulus (GPa) | 2.8 | 3.0 | 3.2 | 1.7 | 9.0 | 10.0 |
| Flexural Strength (MPa) | 100 | 110 | 130 | 75 | 240 | 270 |
| Flexural Modulus (GPa) | 2.6 | 2.8 | 2.9 | 1.6 | 8.5 | 9.2 |
| Notched Izod Impact (J/m) | 55 | 45 | 60 | 45 | 100 | 105 |
| Unnotched Izod (J/m) | No break | No break | 450 | No break | 600 | 700 |
Key Observations: – PA6 has higher elongation (more ductile) but PA66 has higher strength – Glass fiber reinforcement (GF30 = 30% glass fiber) increases strength 2-2.5× but dramatically reduces ductility – PA46 outperforms all standard nylons in both strength and thermal resistance, at higher cost – PA12 is the softest and most flexible — lowest strength but best impact resistance at low temperatures
Thermal Properties
Thermal performance is often the deciding factor in grade selection:
| Property | PA6 | PA66 | PA46 | PA12 | PA6-GF30 |
|---|---|---|---|---|---|
| Melting Point (°C) | 225 | 265 | 295 | 180 | 225 |
| Glass Transition Temp (°C) | 50-60 | 65-70 | 75 | 40-45 | 50-60 |
| HDT @ 0.45 MPa (°C) | 170 | 250 | 285 | 145 | 215 |
| HDT @ 1.82 MPa (°C) | 65 | 90 | 160 | 55 | 195 |
| Continuous Service Temp (°C) | 100-115 | 130-150 | 170-180 | 80-95 | 140-160 |
| Thermal Conductivity (W/m·K) | 0.25 | 0.25 | 0.30 | 0.23 | 0.47 |
| Specific Heat (J/g·K) | 1.7 | 1.7 | 1.4 | 1.6 | 1.3 |
HDT Notes: – Heat Deflection Temperature (HDT) measures temperature at which a specimen deflects 0.25mm under specified load – Glass fiber reinforcement dramatically improves HDT — GF30 grades achieve 2-3× the HDT of unfilled grades at 1.82 MPa – PA66-GF30 at 1.82 MPa: 250°C — suitable for under-hood automotive applications – PA12’s low HDT limits use to room-temperature applications
PC 3D Printing Guide Engineering Plastics Cost Outdoor Plastic Selection Nylon Moisture Drying Guide Nylon Chemical Resistance
Moisture Absorption and Environmental Effects
Nylon’s moisture absorption is a critical consideration — more so than almost any other engineering plastic:
| Grade | Moisture Absorption (24h, 50% RH) | Moisture Absorption (saturation, 23°C/50% RH) | Equilibrium Humidity |
|---|---|---|---|
| PA6 | 1.6% | 9.5% | 2.5-3.0% |
| PA66 | 1.2% | 8.5% | 2.5% |
| PA46 | 1.2% | 6.5% | 2.0% |
| PA12 | 0.3% | 1.5% | 0.7% |
| PA11 | 0.4% | 2.0% | 0.8% |
Impact of Moisture on Properties: – Tensile strength decreases 15-25% at saturated condition vs. dry-as-molded – Impact resistance INCREASES with moisture absorption (nylon becomes tougher when conditioned) – Dimensional change: PA6 swells approximately 0.4% per 1% moisture absorbed — must be accounted for in precision parts – Electrical insulation properties degrade significantly with moisture (dielectric constant increases 2×)
Design Recommendations: – PA12 for parts exposed to humid environments or water immersion – Dry-as-molded properties for designing dimensional tolerances in molds – Condition parts to equilibrium before measuring critical dimensions
Chemical Resistance of Nylon
Nylon’s chemical resistance profile determines suitability for industrial environments:
Good Resistance (no significant attack at 23°C): – Aliphatic hydrocarbons (gasoline, mineral oils, diesel) – Alcohols (methanol, ethanol, isopropanol) – Esters and ketones (acetone, MEK — limited exposure) – Weak acids (acetic acid, citric acid — verify case-by-case) – Dilute alkalis and salts
Poor Resistance (attack or degradation): – Concentrated mineral acids (HCl, H2SO4, HNO3) — rapid hydrolysis – Strong oxidizing agents (hydrogen peroxide >10%) – Phenol and formic acid — dissolves nylon – Calcium chloride (desiccant) — causes stress cracking – Strong alkalis at elevated temperature
Specialty Grades for Chemical Service: – PA12 for automotive fuel lines — resistant to aromatic fuels and alcohol blends – PA6I/6T (transparent nylon) for chemical contact applications requiring clarity – Glass-filled grades for chemical pump housings and valve components
Electrical and Flammability Properties
Electrical Properties (at 50% RH conditioning):
| Property | PA6 | PA66 | PA12 |
|---|---|---|---|
| Dielectric Strength (kV/mm) | 20 | 20 | 18 |
| Volume Resistivity (Ω·cm) | 10^15 | 10^15 | 10^14 |
| Surface Resistivity (Ω) | 10^13 | 10^13 | 10^12 |
| Dielectric Constant (1 MHz) | 3.8 | 3.6 | 3.1 |
| Dissipation Factor (1 MHz) | 0.02 | 0.02 | 0.03 |
Flammability Ratings:
| Grade | UL94 Rating | Oxygen Index (%) |
|---|---|---|
| — | — | PA6 |
| HB | 24 | PA66 |
| HB | 24 | PA12 |
| HB | 22 | PA6-GF30 |
| HB | 23 | FR grades |
| V-0 | 32+ |
Nylon burns with a self-sustaining flame and drips. For electrical enclosures or components requiring flame retardancy, specify FR (flame retardant) grades — typically PA66 with halogen or phosphorus-based flame retardants.
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Frequently Asked Questions
Q: How does moisture affect nylon properties?
A: Moisture acts as a plasticizer in nylon, reducing tensile strength by up to 30% at saturation, but increasing impact strength and elongation. Dry nylon (0.2% moisture) is brittle and strong; conditioned nylon (2.5% moisture) is tougher and more flexible. Design for conditioned properties in humid applications.
Q: What’s the relationship between crystallinity and properties?
A: Higher crystallinity increases tensile strength, stiffness, and chemical resistance, but reduces impact strength and dimensional stability during molding. PA66 has higher crystallinity than PA6, contributing to its superior heat resistance and lower moisture absorption. Processing conditions affect final crystallinity—faster cooling yields lower crystallinity.
Q: How do I interpret the melt temperature range?
A: Melt temperature is the processing window, not a single point. PA6 melts at 220°C, PA66 at 260°C. Process 10-30°C above melt temperature for proper flow. Exceeding degradation temperature (typically 300°C for PA6, 330°C for PA66) causes molecular breakdown, discoloration, and property loss.
Q: What testing standards should I reference?
A: Key standards include ASTM D638 (tensile), D790 (flexural), D256 (Izod impact), D570 (water absorption), and D696 (thermal expansion). ISO equivalents include 527, 180, 62, and 11359. Always specify test conditions (dry/as-molded, temperature, humidity) as nylon properties vary significantly with conditioning.
