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Views: 0 Author: Site Editor Publish Time: 2025-07-02 Origin: Site
Nylon 66, also known as polyamide 66 (PA66), is one of the most widely used engineering plastics in the world. Renowned for its strength, thermal stability, and resistance to chemicals, it’s a go-to material in high-performance applications across automotive, electronics, and industrial sectors.
But if you're designing components that operate under intense heat—like cooling fans, engine parts, or electric connectors—one crucial question arises: what is the melting point of nylon 66? How does it compare to other nylons or thermoplastics? And which grade should you choose to ensure your product holds up under thermal stress?We’ll explore the melting point of nylon 66, the factors that affect it, its thermal properties, and the best high-temperature nylon 66 grades for demanding applications.
Nylon is a synthetic polymer belonging to the polyamide family. It’s made through the polymerization of diamines and dicarboxylic acids or lactams. Nylon 66 is specifically made from hexamethylenediamine and adipic acid, giving it a highly crystalline structure that contributes to its heat resistance.
Nylon 66 is composed of repeating units of carbon chains, with strong hydrogen bonds between molecular chains. This tight crystalline structure leads to a higher melting point compared to other nylons like nylon 6 or nylon 12.
The melting point of nylon 66 is significantly higher than many other polyamides. Its symmetrical molecular configuration offers better heat resistance, chemical stability, and mechanical strength—making it ideal for applications exposed to high or fluctuating temperatures, such as automotive cooling system water pipes and fittings.
Different types of nylon have varying melting points depending on their molecular structure. Here's a comparison of the most common types:
| Nylon Type | Melting Point (°C) | Melting Point (°F) |
|---|---|---|
| Nylon 6 | ~220°C | ~428°F |
| Nylon 66 (PA66) | ~255–265°C | ~491–509°F |
| Nylon 12 | ~178°C | ~352°F |
| Nylon 11 | ~185°C | ~365°F |
| Glass-Filled PA66 | ~265–280°C | ~509–536°F |
The melting point of nylon 66 is approximately 255–265°C (491–509°F), depending on the grade and additives used.
Beyond melting point, nylon 66 demonstrates several important thermal behaviors that influence its performance in industrial applications.
As mentioned, nylon 66 melts at 255–265°C, making it one of the highest melting nylons. This allows it to retain mechanical properties in high-heat environments.
This is the temperature where the nylon transitions from a rigid to a rubbery state. For nylon 66:
Tg: ~50°C (122°F)
Nylon 66 has low thermal conductivity, which makes it a good insulator. However, in reinforced grades, this may slightly improve.
Thermal conductivity: ~0.25 W/m·K
This is the temperature at which a material deforms under load:
HDT (unfilled): ~75–85°C
HDT (glass-filled): ~200–230°C
Glass fiber reinforced nylon 66 plastic pellets are often used when high HDT is required.
Nylon 66 expands with temperature, but reinforced grades show reduced expansion.
Coefficient of thermal expansion: ~80–100 × 10⁻⁶ /°C
Thermal decomposition of PA66 begins around 350°C, beyond which chemical breakdown begins.
Standard nylon 66 is flammable, but halogen free flame retardant nylon 66 plastic pellets are available for applications requiring UL94 V-0 fire ratings, especially in electronic housings and connectors.
Though the melting point of base nylon 66 is well established, several factors can influence it in real-world applications.
Higher crystallinity leads to a sharper and higher melting point. Nylon 66 is highly crystalline, which is why it offers better thermal performance than nylon 6.
Nylon is hygroscopic and absorbs moisture, which can lower the effective processing temperature and overall dimensional stability. Drying the resin before molding is essential.
Glass fibers increase the HDT and dimensional stability.
Flame retardants may slightly reduce the melting point but improve safety.
Lubricants improve flow but may slightly lower thermal performance.
Modified materials such as abrasion resistant self lubricating nylon 66 plastic pellets are optimized for friction-heavy applications like seat rails and adjustment mechanisms.
Due to its thermal stability, nylon 66 is used in applications that demand consistent performance across a wide temperature range.
Hydrolysis resistant, glycol resistant nylon 66 plastic pellets are engineered to withstand hot water and engine coolant environments. They are used for:
Radiator tanks
Hose connectors
Thermostat housings
Air conditioner vent blades and cooling fans require materials that resist heat and maintain dimensional accuracy. Nylon 66 grades with added UV stabilizers and glass fibers are preferred.
For parts like cylinder heads, oil pans, and fuel system components, oil resistant nylon 66 plastic pellets provide superior performance under long-term exposure to lubricants and heat.
Charging cable plugs and connectors in electric vehicles require materials that are heat-resistant, flame retardant, and electrically insulating. Halogen free flame retardant nylon 66 plastic pellets meet these demands.
In industrial machines, nylon 66 is used for:
Bearings
Sliders
Gears
Glass fiber reinforced grades offer the strength and heat resistance needed for continuous operation.
Not all nylon 66 is created equal. Selecting the right grade based on your temperature and environmental requirements is critical. Below are some of the most widely used modified grades:
| Grade Type | Key Features | Recommended Applications |
|---|---|---|
| Glass fiber reinforced nylon 66 plastic pellets | High strength, HDT, dimensional stability | Engine covers, seat rails, sliders |
| Hydrolysis resistant, glycol resistant nylon 66 | Resistant to hot water and coolants | Automotive cooling system water pipes and fittings |
| Oil resistant nylon 66 plastic pellets | Withstands long-term contact with oil | Oil pans, fuel system parts |
| Halogen free flame retardant nylon 66 | UL94 V-0, low smoke and toxicity | Charging cable plugs, connectors |
| Abrasion resistant self lubricating nylon 66 | Reduced friction and wear | Industrial gears, seat adjustment mechanisms |
Companies like Uniking offer custom-engineered nylon 66 plastic pellets tailored to meet specific thermal, chemical, and mechanical requirements.
How does nylon 66 stack up against other commonly used engineering plastics?
| Material | Melting Point (°C) | HDT (°C) | Flame Retardant Grades Available | Typical Use |
|---|---|---|---|---|
| Nylon 66 | 255–265 | 75–230 | Yes | Automotive, electronics |
| Nylon 6 | ~220 | 65–200 | Yes | Consumer goods |
| PBT | ~225 | 60–200 | Yes | Connectors, appliances |
| ABS | ~105 | 85–100 | Yes | Enclosures |
| PP | ~160 | 50–100 | No | Packaging, casual use |
As the table shows, nylon 66 offers superior thermal performance compared to other standard thermoplastics, making it an ideal choice for high-temperature environments.
Q1: What is the melting point of nylon 66?
A1: Nylon 66 melts at approximately 255–265°C (491–509°F), depending on the grade and reinforcements used.
Q2: How does nylon 66 compare to nylon 6 in terms of temperature resistance?
A2: Nylon 66 has a higher melting point and better thermal stability than nylon 6, making it more suitable for demanding environments.
Q3: Can nylon 66 withstand engine heat?
A3: Yes, especially when using hydrolysis resistant, glycol resistant nylon 66 plastic pellets, which are designed for continuous exposure to hot fluids.
Q4: Which nylon 66 grade is best for oil exposure and heat?
A4: Oil resistant nylon 66 plastic pellets are ideal for parts like oil pans and fuel system components.
Q5: Does nylon 66 melt or burn at high temperatures?
A5: Nylon 66 melts around 265°C but begins to decompose around 350°C. Flame retardant grades prevent ignition in electronic or automotive applications.
Q6: What’s the difference between glass fiber reinforced and standard nylon 66 at high temperatures?
A6: Glass-filled nylon 66 has a higher HDT and better dimensional stability under heat, making it suitable for structural parts.
Q7: Where can I find high-performance nylon 66 materials?
A7: Uniking offers a wide range of modified nylon 66 plastic pellets, including flame retardant, oil resistant, and glass fiber reinforced grades for various thermal demands.
Knowing the melting point of nylon 66—and how it behaves under heat—is essential when choosing materials for high-performance applications. With a melting point of up to 265°C and excellent heat deflection temperatures, nylon 66 is one of the best thermoplastics for environments where temperature resistance matters.
Whether you're designing radiator fittings, cooling fans, or electrical connectors, selecting the appropriate grade—such as hydrolysis resistant or flame retardant nylon 66 plastic pellets—will ensure your product performs reliably and safely.
With trusted suppliers like Uniking offering tailored nylon 66 solutions, you can confidently meet the thermal demands of the most challenging applications.
