Low-Temperature Modified Nylon Resistant to -40°C

2026-08-04　

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Unmodified PA6/PA66 tends to undergo brittle fracture with notches at -40°C. Two technical routes are available to achieve resistance to -40°C low temperature:
Toughening modification of general PA6/PA66 (mainstream cost-effective solution)
Long-chain nylon substrates (PA610/PA612/PA1010 with inherent cold resistance, higher cost)
Key test indicator: -40°C Notched Izod Impact Strength (ISO 180)
Reliable engineering standard: ≥6 kJ/m² without brittle fracture

1. Substrate Selection Comparison

Substrate	Inherent Cold Resistance	Advantages & Disadvantages	Application Scenarios for -40°C Service	Cost Level
PA6	Poor; embritles below -20°C	Good flowability, low cost; requires high loading of toughener	Non-structural housings, fasteners, non-load-bearing components	Low
PA66	Moderately poor; embritles below -25°C	High strength, good heat resistance; rigidity decreases significantly after toughening	Automotive structural parts, electrical brackets	Medium
PA610	Good; inherently resistant to -40°C	Low water absorption, stable dimensional stability, oil resistance	Hydraulic fittings, valve components, precision parts	Medium-High
PA612	Excellent; ductile-brittle transition temperature ＜-50°C	Lowest water absorption, low warpage	Precision sensors, outdoor instruments	High
PA1010	Superior; ductile-brittle transition ≈-60°C	Wear resistance, low water absorption, good low-temperature flexibility	Sliding bushes, friction pairs, pipelines	High

2. Toughening System Selection (Critical for -40°C Performance)
All tougheners must adopt MAH-grafted grades (g-MAH) to guarantee interfacial compatibility with nylon
2.1 POE-g-MAH (Octene-based POE｜Preferred Solution)
Glass transition temperature Tg ≈ -58~-70°C, ideal for -40°C service
Recommended grades: Dow Engage 493D, domestic high-graft octene POE
Loading dosage: 12 wt%～22 wt%
12%~16%: Balanced rigidity and toughness, retained mechanical strength
18%~22%: Super-toughened, drastically improved low-temperature impact at -40°C
Drawback: Low melting point (~55°C); risk of softening under long-term service above 80°C
2.2 EPDM-g-MAH
Superior heat resistance to POE, excellent fatigue resistance, resistant to repeated bending under temperature cycling
Suitable for automotive cable ties, dynamically reciprocating components
Poor melt flow; high dosage may cause surface blooming and narrow processing window
2.3 SEBS-g-MAH
High temperature resistance, weatherability, low VOC
High material cost; inferior low-temperature toughening efficiency vs octene POE; not the first choice for general -40°C modification
Pitfall Reminder: Ungrafted POE / raw EPDM show poor compatibility with nylon and barely deliver low-temperature toughening effect!
3. Mature Reference Formulations (Weight Parts, Twin-Screw Extrusion)
Formula A: Super-Toughened Cold-Resistant PA66 (Non-Glass-Filled, General Structural Parts, No Brittle Failure at -40°C)
PA66 Resin: 78
Octene POE-g-MAH: 20
Antioxidant Package (1098 + 168): 0.4～0.6
Lubricant (EVA Wax / Zinc Stearate): 0.3～0.5
Optional: Nucleating Agent 0.2 (improves crystallization and reduces warpage)
Typical Property Reference
Room-temperature Notched Izod Impact: ≥45 kJ/m²
-40°C Notched Izod Impact: ≥9 kJ/m² (ductile failure, no brittleness)
Formula B: Glass-Filled Cold-Resistant PA66 (GF15/GF20, Balanced Rigidity & Low-Temperature Impact)
PA66: 62
Glass Fiber 20%: 20
POE-g-MAH: 16
Antioxidant & Lubricant Package: 1.5
Silane Coupling Agent: 0.3
Important Note: Toughening glass-reinforced nylon is more challenging. Maximum toughener loading is recommended at 16%, excessive addition leads to sharp modulus drop. If -40°C impact fails to meet requirements, 5%~10% PA610 can be blended to improve low-temperature toughness.
Formula C: Low-Cost Cold-Resistant PA6 (Non-Load-Bearing Parts)
PA6: 75～80
POE-g-MAH: 18～22
Antioxidant System: 0.5
Remark: PA6 features higher water absorption; low-temperature impact differs greatly between dry and conditioned states. Not recommended for long-term outdoor service.
4. Long-Chain Nylon Solution (Minor Toughener Loading, Low Water Absorption Priority)
Take PA610 as example (intrinsically cold-resistant):
PA610: 90
POE-g-MAH: 8～10
Antioxidant: 0.5
Advantages: Meets -40°C requirement with small amount of toughener; far lower water absorption than PA6/PA66, stable dimension, ideal for precision hydraulic and electrical connectors.

5. Key Processing & Design Guidelines (Determine Low-Temperature Performance)
Thorough Drying – Top Priority
Nylon moisture content ＜0.2%; residual moisture will trigger sharp decline in low-temperature impact strength.
Drying condition: 80~90°C, 4~6 hours
Processing Temperature
PA66 grades: 250~270°C; avoid prolonged high-temperature residence to prevent elastomer degradation
Moderate shear in twin-screw extruder to achieve uniform dispersion of elastomer (optimal particle size: 0.2~1 μm)
Product Structural Design
Avoid sharp notches and small radii on corners; notches are the primary cause of low-temperature brittle cracking
Prevent drastic wall thickness variation to minimize internal residual stress
Aging Resistance Consideration
For long-term outdoor cycling (-40°C ~ 80°C): add light stabilizer and carbon black (0.3~1%) to prevent elastomer aging and embrittlement.
6. Quick Material Selection Guidance
Limited budget, no glass fiber → PA66 + 18% octene POE-g-MAH
Glass fiber reinforcement required together with -40°C resistance → PA66-GF20 +14~16% POE, lab trial recommended
Low water absorption, precision components, long-term temperature cycling → PA610/PA612 substrate with minor toughener
Repeated bending & wide temperature fluctuation (cable ties, clips) → Replace POE with EPDM-g-MAH

* The above information is for reference only and may not fully match your target product. Please share your specific requirements, and we will assist you with material selection.

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