We encounter nylon every day—it was first used as a silk substitute in fabrics, and during WWII it appeared in parachutes, life-vest cords, and even bulletproof vest linings. Today, nylon is one of the most popular engineering plastics, thanks to its high strength-to-weight ratio, self-lubricating wear resistance, chemical and thermal stability, and processing versatility.
Nylon is the trade name for a family of synthetic polymers known as polyamides, first developed by DuPont between 1935 and 1937. Its molecular chains consist of repeating –NH–CO– (amide) linkages, and hydrogen bonds between these chains create increased crystallinity. This structure gives nylon a high melting point, excellent chemical resistance, and superior electrical-insulating properties. As a thermoplastic, nylon can be spun into fibers, cast into films, or injection-molded into complex shapes, and can be modified with additives to achieve a wide range of properties. In the next sections, we’ll explore several of the most common nylon grades and how their distinct properties suit different applications.
Before diving into the details, the table below offers a concise overview of the key characteristics of each nylon grade.
| Nylon Grade | Monomer Used | Chemical Structure (repeat unit) | –(CH₂)– Count | Tensile Strength (MPa) | Elongation at Break (%) | Flexural Modulus (GPa) | Impact Resistance | Moisture Absorption | Melting Temp. (°C) | Chemical Resistance | Dimensional Stability |
| PA6 | ε-Caprolactam | –[NH–(CH₂)₅–CO]n | 5 | 80–90 | 50–300 | ~2.5 | High (very tough) | ~2.8 (up to ~9 at saturation) | ~220 | Very good; attacked by strong acids/alkalis | Fair (swells in humidity) |
| PA6/6 | Hexamethylenediamine + Adipic acid | –[NH–(CH₂)₆–NH–CO–(CH₂)₄–CO]n | 6, 4 | 85–95 | 20–80 | ~3.0 | Moderate (more brittle) | ~2.5 (up to ~8 at saturation) | 255–265 | Excellent oils/fuels resistance; low gas permeability | Fair (swells in humidity) |
| PA4/6 | 1,4-Diaminobutane + Adipic acid | –[NH–(CH₂)₄–NH–CO–(CH₂)₄–CO]n | 4, 4 | 90–100 | ~50 | ~3.2 | High (very tough) | ~3.8 (higher than PA6/6) | ~295 | Very good; similar to PA6/6 (resists fuels/oils) | Fair–Poor (absorbs the most moisture) |
| PA11 | 11-Aminoundecanoic acid | –[NH–(CH₂)₁₀–CO]n | 10 | 50–60 | 200–300 | ~0.9 | Moderate (flexible) | ~0.25 (up to ~2.5 at saturation) | ~188 | Excellent; outstanding hydrocarbon & chemical resistance | Excellent (minimal swelling) |
| PA12 | Laurolactam (or HMDA + Dodecanedioic acid) | –[NH–(CH₂)₁₁–CO]n | 11 | 50–70 | 200–300 | ~1.4 | Mod–High (very ductile) | ~0.25 (up to ~1–2 at saturation) | ~178 | Excellent; very resistant to fuels, solvents, weather | Excellent (most dimensionally stable) |
| PA6/10 | Hexamethylenediamine + Sebacic acid | –[NH–(CH₂)₆–NH–CO–(CH₂)₈–CO]n | 6, 8 | 60–70 | ~150 | ~2.1 | High (tough in cold) | ~1.5 (low) | 220–225 | Excellent chemical & salt resistance | Good (low moisture uptake) |
| PA6/12 | Hexamethylenediamine + Dodecanedioic acid | –[NH–(CH₂)₆–NH–CO–(CH₂)₁₀–CO]n | 6, 10 | 60–65 | ~200 | ~2.2 | Mod–High (tough) | ~0.25 (very low) | 215–218 | Excellent; very resistant to fuels, oils | Excellent (highly stable in humidity) |
Note
Tensile and elongation values are for unreinforced nylons (approximate ranges). Moisture absorption is given at equilibrium under ~50% relative humidity (approximate), with full water saturation values being higher for most nylons. “Impact resistance” refers to notched impact (Izod/Charpy) . All nylons have good chemical resistance to oils, greases, and hydrocarbons; differences are noted only where significant.
The numbers in a nylon’s name tell you about its molecular building blocks. A single number (for example, Nylon 6, 11, or 12) comes from the ring-opening polymerization of a lactam or amino acid—where that number equals the carbon atoms in the monomer. Two numbers (for example, Nylon 6/6, 6/12, 4/6, or 6/10) refer to a condensation reaction between a diamine (first number = its carbon count) and a diacid (second number = its carbon count).
The average –CH₂– segment length (n) controls both the spacing between amide links and the number of –NH···O=C– hydrogen bonds that can form per unit length. A larger n means longer methylene segments, which lowers hydrogen-bond density and typically reduces crystallinity. For example, PA12 (n = 11) has the longest spacing and lowest crystallinity, whereas PA4/6 (n = (4 + 4)/2 = 4) has the shortest segments, highest hydrogen-bond density, and greatest crystallinity. If you introduce aromatic rings, copolymer blocks, fillers, or other specialty modifiers, these structural changes can disrupt regularity and shift crystallinity, so always refer to specific datasheets or test data to understand their effects.
Nylon 6 (PA6) is a semi-crystalline polyamide produced by ring-opening polymerization of ε-caprolactam. One of its standout features is excellent impact resistance; it can absorb shocks even at low temperatures without fracturing. PA6 also offers high tensile strength, self-lubricating properties, and outstanding abrasion resistance. As a result, PA6 is the go-to choice for general-purpose engineering components that demand a balance of strength, wear resistance, and toughness, such as gears, bearing bushings, and automotive intake manifolds. In the fiber sector, it is widely used in carpets, textiles, and tire cord. With a melting point around 220 °C and more gradual crystallization, PA6 is easier to process than PA6/6 and long-chain nylons such as PA11 and PA12, delivering lower mold shrinkage and smoother finishes. This ease of molding makes PA6 especially well suited to complex or thin-walled parts like stadium seats and firearm frames.
PA6 has the highest moisture absorption among common nylons, so it may not be ideal for precision parts exposed to humidity changes. For tight-tolerance applications, sealing or pre-drying is recommended.Overall, PA6 is the generalist of the nylon family as it strikes a balance between cost, processability, and performance.
Nylon 6/6 (PA66) was one of the original nylons and is very similar to Nylon 6 in many respects, but it has more highly crystalline polymer chains. As a result, it offers higher tensile strength and stiffness than Nylon 6. It is also harder and more wear-resistant, which benefits high-load or high-friction applications. Nylon 6/6’s melting point is around 260 °C (500 °F)—higher than Nylon 6—so it can withstand higher operating temperatures before softening and is suitable for more demanding thermal environments. The trade-off is processability: Nylon 6/6 can be harder to mold or extrude, requiring higher melt and mold temperatures and tending to show greater mold shrinkage than Nylon 6.
Nylon 6/6 is also slightly less prone to moisture absorption than Nylon 6, but it is still hygroscopic, so humidity must be considered for tight-tolerance parts. It is generally less impact-resistant than Nylon 6; in other words, Nylon 6 is better suited for impact strength or vibration resistance, whereas Nylon 6/6 is preferred when higher yield strength, stiffness, and heat resistance matter most. In practice, Nylon 6/6 is often used in similar applications to Nylon 6 when extra performance is needed—for example, high-strength mechanical parts, gears, housings, and automotive under-hood components that see elevated temperatures. It is also common in industrial machinery, tooling, and electrical components, where it retains strength across a wide temperature range and provides good dielectric properties.
As another short-chain aliphatic nylon, PA4/6 most closely matches PA66 in mechanical and thermal profile. This polymer has a highly crystalline structure—more so than PA6 or PA66—owing to the symmetry and short length of the diamine. As a result, PA4/6 has a higher melting point and higher tensile strength; among aliphatic nylons it is effectively near the top for mechanical performance before you move into more specialized polymer families. It also crystallizes faster, enabling shorter molding cycles and potentially higher fatigue resistance. PA4/6’s impact toughness can exceed that of PA66 (especially in notched tests), which is notable given how stiff it is.
On the downside, PA4/6 absorbs more moisture than PA66 and is more costly to produce (and to purchase). One might say PA4/6 raises the bar on nylon performance at the expense of moisture stability and cost.
Nylon 11 is a bio-based, long-chain polyamide produced by self-condensation of 11-aminoundecanoic acid (from castor oil). Its long methylene segments make it far less polar than short-chain nylons such as PA6 and PA66, so it absorbs very little moisture (≈0.2–0.3% at ambient humidity), remains dimensionally stable, and maintains electrical properties in damp environments. Mechanically it is tough and very ductile (elongation often 200–300%), and it retains impact and fatigue resistance even at low temperatures—so in practice it behaves more like a flexible engineering plastic than a rigid one.
The flip side of that long-chain structure is lower tensile strength/stiffness and lower heat resistance (melting point ~185–190 °C; modest HDT), so PA11 isn’t ideal for hot, heavily loaded structural parts, where PA66 or PA4/6 are typically specified. PA11 is well suited to fluid-contact and outdoor service: flexible fuel and pneumatic brake lines, hoses/quick-connects, cable jackets, seals, and medical or industrial tubing. It’s also a staple powder for SLS 3D printing when tough, impact-resistant parts are required. Compared with PA12, PA11 offers a slightly higher melting point and typically better UV/hot-air aging, while PA12 tends to be a touch softer and more flexible.
PA12 is a well-known “long-chain” nylon, often associated with trade names like Vestamid or Grilamid. Nylon 12 is chemically very similar to Nylon 11 and is often considered interchangeable in many uses, but there are subtle differences. Nylon 12 is entirely petrochemical (typically from butadiene), whereas Nylon 11 is bio-based from renewable castor oil, which can matter if sustainability is a concern. PA11 typically has a slightly higher melting point, performs a bit better at elevated temperatures, and often shows better UV resistance. PA12, on the other hand, is slightly more flexible (elongation ~300–400% vs. PA11’s ~200–300%) and has a slightly lower modulus, so it feels a bit softer. For moisture absorption and chemical resistance, they are virtually the same—both are superb.
It’s worth noting cost: PA12 is usually among the most expensive nylons (with PA11 on par or a bit higher due to its bio-based feedstock). As such, PA12 is used when its unique benefits are truly required—you wouldn’t choose PA12 where PA6 would suffice, because PA6 is much cheaper. In summary, PA12 offers some of the best dimensional stability and chemical resistance in the nylon family and remains ductile even in freezing conditions, making it ideal for hoses, seals, quick-connects, cable jackets, and other parts that must not fail in wet, cold, or chemically aggressive environments. However, it is not as strong or heat-resistant as PA6 or PA66, so it’s a specialist rather than a universal replacement.
Nylon 6/10 (PA610) was one of the early “low-moisture” nylons developed to address PA66’s humidity issues. With fewer amide groups per unit length, it is less polar and absorbs roughly half (or less) of PA6’s moisture, delivering better dimensional stability. It also shows good elongation like other long-chain nylons and retains toughness in the cold, making it suitable for outdoor or low-temperature parts. Compared with PA6/PA66, PA610 has slightly lower tensile strength and stiffness; overall, think of PA610 as a nylon that trades a bit of strength and rigidity for better moisture stability and flexibility.
Its melting point (~220–225 °C) and moderate shrinkage make molding/extrusion conditions close to PA6. Chemically, PA610 is excellent: it resists most oils and solvents and is notably resistant to environmental stress cracking in the presence of salts such as zinc chloride (which can aggressively attack PA66). Because part of its content (sebacic acid) comes from renewable sources, it’s sometimes marketed as a more sustainable nylon option. Classic uses include bristles and filaments (e.g., toothbrush and industrial brush bristles—historically DuPont “Tynex” grades), monofilament (fishing line, weed-trimmer line). In molded parts, PA610 is used for electrical insulators/connectors, precision components, zipper elements, and some automotive fuel-system components (though PA12 and PA11 dominate continuous fuel lines). Compared with PA12, PA610 is cheaper and a bit stronger, so it can replace PA12 in less demanding roles. In short, PA610 fills a niche as an intermediate nylon—giving up some of PA66’s peak strength to gain much of PA12’s moisture stability, often at a reasonable cost; it’s especially handy for semi-wet environments or parts that must keep properties in the cold.
PA612 (sometimes called “612 nylon”) is very similar to PA610: both have low moisture uptake and far better dimensional stability than PA6/PA66, stay tough outdoors and at low temperatures, and have a melting point around 215–218 °C, so molding/extrusion conditions are close to PA6. Both are well-suited to fluid-handling connectors, precision electrical connectors, and humidity-exposed parts that must hold tight dimensions.
PA612’s equilibrium moisture absorption is lower, its fuel/water-vapor permeation is lower, and its wet-state property drift is smaller—but it typically costs more. As a rule of thumb, choose PA612 for wet environments where long-term dimensional and electrical stability are critical; pick PA610 when extreme low-temperature toughness or resistance to stress cracking in zinc-chloride environments matters more and cost sensitivity is higher.
Each nylon grade—from Nylon 6 and 6,6 to the short-chain aliphatic Nylon 4,6 and the long-chain Nylon 6,10, 6,12, 11, and 12—offers a distinct balance of properties. Nylon 6 and 6,6 are general-purpose workhorses with high strength and stiffness, suitable for many load-bearing parts but sensitive to moisture. Nylon 4,6 raises heat resistance and retains high strength for high-temperature, high-stress uses, albeit with higher moisture uptake and cost. Moving to longer chains, Nylon 6,10 and 6,12 reduce moisture absorption and improve toughness at the cost of a bit of strength—excellent for parts needing stability in humid or cold settings. Finally, Nylon 11 and 12 offer among the best moisture and chemical resilience and exceptional toughness, making them go-to choices for fluid-contact, outdoor, and flexible applications—although their lower melting points and higher price confine them to niche but critical roles.
Ready to build? Chiggo specializes in CNC machining, 3D printing, and injection molding of nylon parts. We can help you choose the right grade ,optimize your design for moisture/shrinkage/warpage, and deliver from rapid prototypes to production. Upload your CAD for a fast DFM review and quote.
制造过程通常会在产品表面留下不规则的纹理。随着对高质量饰面的需求不断增长，表面饰面的重要性变得越来越重要。表面处理不仅仅是为了美观或实现更光滑的外观；它显着影响产品的功能、耐用性和整体性能。
选择不锈钢厨具和餐具时，您经常会看到标有18/8、18/10和18/0的成绩。这些数字表明铬和镍的大约百分比，这是定义合金特性的两个关键要素。铬在钢表面形成氧化铬（CR₂O₃）的保护层，以防止生锈和氧化。镍稳定了面部中心的立方（FCC）结构，从而具有钢延展性，韧性和非磁性特性。它还增强了耐腐蚀性，并提供更明亮，更光滑的饰面。
当谈到金属表面处理时，阳极氧化通常是第一个想到的方法，尤其是铝。然而，还有一种更通用的替代方案：电镀。与仅限于特定金属的阳极氧化不同，电镀适用于更广泛的材料。通过在零件上沉积一薄层金属，可以显着增强零件的外观、耐腐蚀性、耐用性和导电性。
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