Products · PA66
Polyamide 66 (PA66, Nylon 66) is one of the highest-volume engineering thermoplastics. Produced by polycondensation of hexamethylenediamine and adipic acid, PA66 offers higher strength, higher melting point (255°C vs 220°C for PA6), and better high-temperature performance than PA6 — at a modest cost premium. Glass-fiber-reinforced grades (15-43% GF) are the workhorse for automotive structural parts, under-hood components, and industrial fasteners where stiffness, creep resistance, and fatigue performance are critical. Reference grades from DuPont (Zytel), Solvay (Technyl), Ascend (Vydyne), and domestic Chinese suppliers (Shenma 神马, Huafon 华峰) cover the full property and processing range.
Section 1
A reference overview of the molecular architecture and the design variables that govern the performance of this polymer family.
PA66 is produced by the polycondensation of hexamethylenediamine (HMDA) and adipic acid, both C6 monomers, giving the polymer its name. The reaction is a step-growth polymerization that releases water, requiring precise stoichiometry to achieve high molecular weight. The all-aliphatic backbone with regular amide (–CONH–) groups along the chain gives PA66 a high melting point (255°C), high crystallinity (up to 50%), and strong hydrogen bonding between chains. Compared to PA6 (caprolactam ring-opening), PA66 has more uniform repeat units, which translates to higher modulus, lower ductility, and better high-temperature creep resistance. Glass-fiber reinforcement is the dominant modification: GF coupling agent (typically epoxy or silane-based) on the fiber surface is essential for transferring stress from matrix to fiber.
Section 2
Typical property ranges across commercial grades. Test methods are listed in the rightmost column for traceability to public manufacturer data sheets.
PA66's property profile is dominated by its high crystallinity and strong hydrogen bonding. Compared to PA6, PA66 has higher melting point, higher modulus, better high-temperature performance, and lower water absorption at saturation. Glass-fiber-reinforced grades dramatically increase stiffness, strength, and HDT, but reduce ductility and increase mold shrinkage anisotropy.
| Property · 性能 | Unfilled PA66 | 33% GF PA66 | Test Method · 测试方法 |
|---|---|---|---|
| Density · 密度 | 1.13 – 1.15 g/cm³ | 1.38 – 1.42 g/cm³ | ASTM D792 |
| Melt Point · 熔点 | 255 – 265 °C | 255 – 265 °C | ISO 3146 |
| Tensile Strength · 拉伸强度 | 75 – 90 MPa | 170 – 200 MPa | ASTM D638 |
| Flexural Modulus · 弯曲模量 | 2.8 – 3.2 GPa | 9 – 11 GPa | ASTM D790 |
| Elongation at Break · 断裂伸长 | 30 – 80 % | 3 – 5 % | ASTM D638 |
| HDT (1.82 MPa) · 热变形 | 70 – 90 °C | 240 – 260 °C | ASTM D648 |
| Water Absorption (24h) · 吸水率 | 1.0 – 1.3 % | 0.7 – 1.0 % | ASTM D570 |
Section 3
The major application areas for this polymer family, each illustrated with a brief description of how the material is specified and used.
Glass-fiber-reinforced PA66 (30-35% GF) is widely used in automotive structural applications including engine brackets, transmission crossbeams, pedal boxes, seat frames, and front-end modules. The combination of high stiffness, fatigue resistance, and impact strength at temperatures up to 150°C continuous is unique to PA66 in the engineering polyamide family.
PA66 grades dominate under-hood applications: air intake manifolds, charge air coolers, thermostat housings, coolant reservoirs, and connector housings. Heat-stabilized and hydrolysis-resistant grades are used in direct contact with coolant, oil, and exhaust gas recirculation streams.
PA66 replaces metal in many industrial fasteners, cable ties, gears, and bearings where vibration resistance, fatigue endurance, and weight reduction are priorities. The combination of low coefficient of friction (with lubrication) and high fatigue strength makes PA66 particularly suited for dynamic load applications.
Flame-retardant PA66 grades (UL94 V-0 at 0.8 mm) are widely used in circuit breakers, contactors, motor housings, and electrical connectors. The combination of high HDT, flame retardance, and electrical insulation is valued in consumer and industrial electrical equipment.
PA66 is also produced as high-tenacity industrial fiber for tire cord, conveyor belts, ropes, and airbags. The high melting point and fatigue resistance of PA66 fiber make it the preferred material for radial tire reinforcement and airbag cushion fabric.
Section 4
Key processing parameters and equipment considerations. Contact our business manager for grade-specific processing recommendations.
| Melt Temperature | 270 – 290 °C (unfilled); 280 – 300 °C (GF-reinforced) |
| Drying | 80 °C for 4 – 16 hours (moisture < 0.1%) |
PA66 is highly sensitive to moisture — wet resin hydrolyzes at processing temperatures, causing molecular-weight loss, brittleness, and surface streaks (silver streaking). Drying is mandatory. Molded parts are typically post-conditioning at 23°C/50% RH for 24-48 hours before dimensional measurement to stabilize moisture content and final dimensions.
Section 5
A summary of when this polymer family is the right choice and what to consider as alternatives. For project-specific grade selection, contact our business manager.
Choose PA66 over PA6 when the application requires higher melting point, better high-temperature stiffness, or lower water absorption. Choose PA66 over PPA or PPS when the cost target is the primary driver and continuous use temperature is below 150°C. For applications requiring higher HDT (>260°C) or chemical resistance, PPA, PPS, or polyphthalamide variants are preferred. For impact-modified parts requiring high ductility, PA6 is more cost-effective.
Section 6
Reference grades from publicly available manufacturer catalogs. Complete catalog available on request.
| Grade | Manufacturer | Key Properties | Typical Use |
|---|---|---|---|
| Zytel® 101LNo vendor TDS · source on request | DuPont | Unfilled · Lubricated · Easy flow | General purpose · Cable ties · Fasteners |
| Zytel® 70G33HS1LNo vendor TDS · source on request | DuPont | 33% GF · Heat stabilized · Hydrolysis resistant | Automotive under-hood · Coolant contact |
| Technyl® A218 V30 | Solvay | 30% GF · Heat stabilized | Engine brackets · Structural automotive |
| Vydyne® 21SPFNo vendor TDS · source on request | Ascend Performance Materials | Unfilled · Lubricated · High flow | Fasteners · Cable ties · Consumer goods |
| EPR27 (神马 EPR27) | Shenma (神马) | 30% GF · Domestic supply · Cost-effective | 国产替代 · 工业件 · 汽车件 |
Section 7
Cross-references to industry-specific applications and case studies.