Types of Nylon and Their Classification: PA6, PA66 and Specialty Polyamides

Quick Comparison of the Main Types of Nylon

Nylon type	Main characteristics	Common applications	Points to confirm
PA6	Good toughness, abrasion resistance and processing flexibility	Textile fibers, films and molded parts	Moisture condition, shrinkage and heat-setting requirements
PA66	Higher melting temperature and stiffness than typical PA6	Industrial yarns, apparel fibers and engineering parts	Conditioned strength, dyeing behavior and thermal exposure
PA11 and PA12	Lower moisture absorption, flexibility and low-temperature performance	Tubing, monofilaments, cable coverings and specialty components	Bio-based claim, flexibility and chemical resistance
PA46 and PPA	Higher heat resistance and dimensional stability	Connectors, automotive parts and high-temperature components	Specific grade, reinforcement, HDT and continuous-use temperature
Transparent polyamide	High light transmission with good toughness	Eyewear, filters, inspection windows and transparent housings	Haze, test thickness, drying and chemical exposure
PEBA	Elastic recovery, flexibility and repeated bending performance	Sports equipment, flexible tubing and medical components	Hardness, rebound, fatigue resistance and bio-based percentage
Bio-based nylon	Partly or fully produced from renewable feedstock	Textiles, sports products, tubing and engineering components	Renewable content, traceability and supporting documents

What Is Nylon?

Nylon is the common commercial name for a large family of polyamides, normally abbreviated as PA. Polyamides are polymers with repeating amide groups in their molecular backbone. Because these bonds support strength, toughness and abrasion resistance, nylon appears in fibers, yarns, films, coatings, adhesives and engineering components.

PA6 and PA66 remain the most familiar commercial grades. PA6 comes from caprolactam, whereas PA66 comes from hexamethylenediamine and adipic acid. Meanwhile, PA11, PA12, PA46, PA610, PA612, PA6T and PA9T extend the family into lower-moisture, higher-temperature, flexible or partly bio-based applications.

The numbering system usually refers to the carbon atoms in the monomer or monomers. PA6 uses one six-carbon monomer. In contrast, PA66 uses a six-carbon diamine and a six-carbon diacid. PA610 combines a six-carbon diamine with a ten-carbon diacid.

Still, the number does not define every performance property. The ISO 16396-1 polyamide designation system also considers composition, intended application, processing method, additives, fillers and reinforcing materials. Importantly, the standard does not imply that materials with the same designation will deliver identical performance.

Types of Nylon Classified by Chemical Structure

1. Aliphatic Nylon

Aliphatic nylon has a molecular backbone formed mainly from aliphatic monomers. This group contains the most widely used commercial types of nylon:

• PA6
• PA66
• PA46
• PA56
• PA610
• PA612
• PA1010
• PA11
• PA12

PA6 provides good toughness, abrasion resistance and relatively straightforward processing. As a result, manufacturers use it in textile filament, staple fiber, film and molded parts. PA66 generally offers higher heat resistance and stiffness than PA6, so it is common in both textile and engineering applications.

Typical PA6 grades melt at approximately 215–225°C, whereas PA66 commonly melts around 255–265°C. These figures are general reference ranges rather than purchasing specifications. In practice, copolymers, stabilizers, pigments and reinforcement can change the processing response.

For textile work, moisture condition matters almost as much as melting temperature. Nylon absorbs moisture from the surrounding air. Consequently, its weight, tensile behavior, flexibility and dimensional results can change during storage and testing.

We avoid comparing two yarn cones when one has just been opened and the other has remained in the sample room for several days. Instead, we condition both samples in the same environment before testing. Otherwise, the comparison may show a conditioning difference rather than a real material difference.

PA46 has a more regular molecular structure and crystallizes quickly. Therefore, it offers higher heat resistance than standard PA6 or PA66. Commercial PA46 grades commonly show a melting temperature near 295°C. However, PA46 can absorb more moisture than some long-chain or semi-aromatic polyamides, so dimensional checks still need a defined conditioning method.

2. Semi-Aromatic Nylon and PPA

Semi-aromatic polyamides combine aromatic and aliphatic monomers. Common examples include PA4T, PA6T, PA9T, PA10T and MXD6. Many PA4T, PA6T, PA9T and PA10T systems belong to the commercial PPA, or polyphthalamide, category.

The aromatic rings increase molecular-chain rigidity. Therefore, suitable grades can provide higher heat resistance, lower moisture uptake and better dimensional stability than general-purpose PA6 or PA66. These properties make them useful in electrical connectors, automotive cooling systems, under-hood parts and other components exposed to heat or chemicals.

Pure PA6T has a melting temperature that is too high for convenient conventional melt processing. Consequently, commercial PA6T materials are normally copolymers, such as PA6T/66 or PA6T/6I. The additional monomer lowers the processing temperature while retaining much of the stiffness and thermal performance.

PA9T combines a high melting temperature with low water absorption. For example, selected commercial reinforced grades melt at approximately 300–306°C and are designed for reflow-soldering connectors or automotive components. PA10T follows a similar high-temperature route. However, its longer aliphatic section can produce a different balance of toughness, moisture uptake and thermal behavior.

MXD6 differs from terephthalic-acid-based PPA. It is produced from meta-xylylenediamine and adipic acid. Although its melting temperature is lower than that of many PA9T grades, MXD6 provides high stiffness and useful gas-barrier performance. Therefore, it appears in packaging, reinforced compounds and structural applications.

3. Fully Aromatic Polyamides

Fully aromatic polyamides contain a high proportion of rigid aromatic structures in the polymer backbone. Meta-aramid and para-aramid are the best-known examples. Nomex® is associated with meta-aramid, while Kevlar® is a para-aramid trade name.

These materials provide high heat resistance and strength. However, they are not processed like ordinary PA6 or PA66. Their spinning routes, dyeing behavior and end uses are also different.

In textile sourcing, we normally call these materials aramids rather than conventional nylon. Therefore, protective clothing and industrial fabric specifications should separate ordinary nylon filament from high-performance aramid fiber. Our aramid yarn range shows this difference at the yarn-product level.

Types of Nylon Classified by Application

High-Temperature Nylon

High-temperature nylon is not one single polymer. Instead, the term covers polyamides selected for better property retention at elevated temperatures. PA46, PA4T, PA6T, PA9T, PA10T and related PPA copolymers are the main commercial examples.

PA46 is an aliphatic high-temperature nylon, whereas PA4T, PA6T, PA9T and PA10T are semi-aromatic systems. Their actual performance depends on the base polymer, reinforcement, flame-retardant package, moisture condition and mechanical load.

For this reason, melting temperature should not be treated as continuous-use temperature. A polymer that melts above 300°C cannot necessarily operate continuously near 300°C. Heat-deflection temperature also changes according to the test load and reinforcement level.

Before approving a high-temperature grade, we ask the supplier to confirm:

• Melting temperature and test method
• Glass-transition temperature
• Heat-deflection temperature at a stated load
• Short-term and continuous-use temperature data
• Water absorption under a defined condition
• Glass-fiber or carbon-fiber content
• Flame-retardant classification
• Hydrolysis and chemical-resistance results

PA9T shows why grade-level data matters. Kuraray reports a melting temperature of 306°C and 24-hour water absorption of 0.14% for one PA9T grade reinforced with 30% glass fiber. However, these values should not be copied to every PA9T material. The supplier’s PA9T grade data identifies the composition and test methods behind the figures.

Long-Chain Nylon

Long-chain nylon contains a larger hydrocarbon portion between its amide bonds than PA6 or PA66. Common types include PA11, PA12, PA610, PA612, PA1010, PA1012 and PA1212.

Because these polymers have a lower concentration of polar amide groups, they generally absorb less moisture than short-chain nylon. As a result, suitable grades can remain more flexible at low temperature and retain dimensions more consistently.

Typical applications include fuel lines, pneumatic tubing, cable coverings, precision parts, monofilaments and specialty fibers. In addition, PA610 and PA612 appear in industrial filaments and brush applications where stiffness, moisture resistance and wear performance must stay balanced.

Nevertheless, a longer chain does not improve every property. A lower concentration of amide groups can reduce melting temperature, stiffness or dye affinity. For yarn and filament development, this may affect dyeing conditions, color depth, bonding behavior and heat-setting temperature.

Therefore, we do not select a long-chain nylon only because it absorbs less water. First, we check whether the final product also needs stiffness, deep dyeing, heat resistance or repeated flexing. The balance matters more than one isolated property.

Transparent Nylon

Standard semicrystalline nylon normally looks translucent or opaque because its crystalline regions scatter light. Transparent nylon uses a different molecular design to reduce or disrupt regular crystallization. Manufacturers may use copolymerization, bulky cyclic structures or selected aromatic units to create this effect.

Suitable transparent polyamides can achieve light transmission above 90% at a defined test thickness. Common commercial families include PA PACM12, PA MACM12 and related amorphous or cycloaliphatic copolyamides.

These materials are used in eyewear frames, filters, inspection windows, medical components, appliance parts and transparent housings. However, light-transmission percentage alone is not enough for approval. Test thickness, haze, surface quality, color and previous heat exposure all affect the visual result.

For example, a 2 mm test plaque and a thick molded component may not show the same transparency. Moreover, steam sterilization, cleaning agents, UV exposure or repeated heating can change color and haze. Therefore, optical testing should use the actual component thickness whenever possible.

Drying control is equally important. Because absorbed moisture can create bubbles, silver streaks or unstable optical quality, processors need to follow the grade supplier’s drying instructions. In real production, a transparent resin chip may look acceptable while the molded part still fails the haze requirement.

Nylon Elastomers

Polyether block amide, usually abbreviated as PEBA, is a thermoplastic elastomer made from hard polyamide blocks and soft polyether blocks. By adjusting these blocks, manufacturers can change hardness, flexibility, elastic recovery, low-temperature behavior and moisture response.

PEBA appears in sports footwear, flexible tubing, medical catheters, industrial belts and other products that face repeated bending. In particular, it is useful where the part needs both thermoplastic processing and rubber-like recovery.

Some PEBA grades contain bio-based polyamide blocks. However, the renewable percentage varies by formulation. Therefore, buyers should request the actual bio-based content and supporting documentation instead of assuming that every PEBA product has the same material origin.

Bio-Based Nylon

Bio-based nylon uses renewable biological feedstock for part or all of its monomers. However, bio-based nylon is not automatically recycled or biodegradable. These three terms describe separate material routes:

• Bio-based refers to renewable biological feedstock.
• Recycled refers to recovered pre-consumer or post-consumer material.
• Biodegradable requires degradation under specified conditions and an appropriate test method.

PA11 is the clearest commercial example of bio-based nylon. Its aminoundecanoic-acid monomer can be produced from castor oil. Arkema describes Rilsan® PA11 as a polymer of 100% renewable origin and lists low density, chemical resistance and dimensional stability among its properties.

The PA11 manufacturer information identifies the renewable feedstock behind the claim. Therefore, it provides more useful evidence than a general “green nylon” description.

Other partly or fully bio-based polyamides include selected PA56, PA510, PA610, PA1010 and PA10T routes. Their renewable share depends on which diamine or diacid comes from biomass. For example, a material made with one renewable monomer may be only partly bio-based.

Before accepting an environmental claim, buyers should request:

• Bio-based carbon percentage
• Calculation or test basis
• Raw-material origin
• Chain-of-custody documents
• Third-party certification or test report
• Product-specific carbon-footprint data, if claimed

A renewable feedstock claim does not confirm biodegradability, recycled content or restricted-substance compliance. Likewise, it does not prove a lower environmental impact in every category. Consequently, each claim needs its own evidence.

Modified Nylon and Industrial Grade Names

Nylon classification does not stop at the base polymer. Manufacturers modify PA6, PA66, PA12, PPA and other grades with reinforcement, stabilizers or functional additives. Common modified types include:

• Glass-fiber reinforced nylon
• Carbon-fiber reinforced nylon
• Flame-retardant nylon
• Impact-modified nylon
• Conductive or antistatic nylon
• Lubricated and wear-resistant nylon
• UV-stabilized nylon
• Heat-stabilized nylon

A name such as “Nylon 12 GF30” usually indicates a PA12 base containing approximately 30% glass fiber. Nevertheless, the name does not define every additive, colorant or performance value. Therefore, the technical data sheet still needs to show the test standards and material condition.

Dry-as-molded and conditioned specimens can produce different results. In addition, glass-fiber orientation may change strength and shrinkage between the flow direction and the transverse direction. Buyers should confirm which specimen condition and direction apply to the published data.

How We Select Nylon for Yarn and Knitted Fabric Development

Resin classification helps us understand the polymer. However, yarn development needs another layer of checks. We also look at filament form, denier, filament count, luster, cross-section, twist, oil content, dyeability and machine behavior.

A technically strong polymer can still produce an unsuitable yarn when the filament construction does not match the fabric. For example, a low-denier nylon can improve softness, but it may also change tension control and covering behavior. Meanwhile, a higher-strength filament may support abrasion resistance but give the fabric a firmer hand.

For a nylon-blend trial, we normally work in this order:

1. Confirm the end use, fabric structure and proposed nylon type.
2. Check the yarn count, composition, filament structure and winding form.
3. Condition the sample cones under the same room conditions.
4. Run a small knitting trial or trial roll.
5. Record tension fluctuation, yarn breaks, needle marks and surface uniformity.
6. Check hand feel, stretch recovery and color after finishing.
7. Carry out the agreed wash, abrasion or pilling test.
8. Compare the approved sample with the first bulk lot.

On an 18G sock machine, a nylon blend may look clean on the cone but create tight feeding or uneven loops when the oil level and tension do not suit the machine setting. After washing, another issue may appear. For instance, the fabric may become firmer, lose width or show more surface fuzz.

That is why we keep the knitting record, trial piece and wash result together during development. Later, when the first bulk lot arrives, we can compare it with the approved sample instead of relying on memory.

For warm socks and winter knitwear, nylon is often blended with polyester, acrylic or wool. In these constructions, nylon can support strength and abrasion resistance, while the other fibers contribute bulk, warmth or hand feel. Our thermal warm yarn range includes several nylon-containing blends that show how nylon works alongside other fibers.

What Buyers Should Confirm Before Ordering

Choosing between the different types of nylon depends on the final product and the processing route. Therefore, the purchase specification should cover more than the polymer name.

Before sampling or bulk production, confirm the following points:

• Exact polymer designation and blend composition
• Virgin, recycled or bio-based material status
• Yarn count, denier, filament count and twist
• Required strength and elongation
• Abrasion and pilling requirements
• Moisture-conditioning method used for testing
• Dyeing and heat-setting temperature limits
• Wash and dimensional-stability requirements
• Colorfastness standards
• Restricted-substance documents
• Certification scope and validity
• Approved sample, lab dip and bulk tolerance

In our development work, problems usually start when a material name is approved without fixed test conditions. PA6, PA66, PA12 and PPA each cover many commercial grades. Therefore, “PA66 nylon” or “high-temperature nylon” is not a complete purchasing specification.

An approved sample helps, but it should be supported by measurable tolerances. For yarn, these may include count, composition, strength, elongation, twist, color difference and package weight. For a finished fabric, the specification may also include width, weight, shrinkage, pilling, abrasion and colorfastness.

Frequently Asked Questions About Types of Nylon

What are the most common types of nylon?

PA6 and PA66 are the most common general-purpose types. Meanwhile, PA11 and PA12 are important long-chain polyamides. PA46, PA6T, PA9T and PA10T serve higher-temperature applications, while transparent polyamides, PEBA elastomers and bio-based grades cover more specialized requirements.

What is the main difference between PA6 and PA66?

PA66 generally has a higher melting temperature and greater stiffness. In comparison, PA6 often provides easier processing and good toughness. However, moisture absorption, additives, molecular weight and conditioning can change both materials. Therefore, buyers still need grade-specific data.

Is PA11 the same as recycled nylon?

No. PA11 can be produced from renewable castor oil, which makes it bio-based. Recycled nylon, by contrast, comes from recovered production waste, fishing nets, carpets, textile waste or other nylon sources. A material could be both bio-based and recycled, but each claim needs separate documentation.

Which nylon absorbs the least moisture?

Long-chain polyamides such as PA11 and PA12 generally absorb less moisture than PA6 and PA66. In addition, selected PA9T and PPA grades offer low water absorption. However, the comparison must use the same test method, exposure time, temperature and specimen condition.

Is high-temperature nylon suitable for textile yarn?

Some high-performance polyamides can be made into fibers. Nevertheless, many commercial PPA grades are designed mainly for injection molding or extrusion. PA6 and PA66 remain more practical for most apparel and industrial yarns. When much higher heat resistance is required in a textile, aramid may be the more appropriate material.

Does a higher melting point always mean better nylon?

No. A higher melting point may help in high-temperature processing or use, but it can also require more demanding equipment and tighter moisture control. Moreover, the final product may need flexibility, transparency, low-temperature impact resistance or easier dyeing instead. The best grade depends on the complete requirement.

Can bio-based nylon be called biodegradable?

Not without suitable test evidence. Bio-based describes the origin of the feedstock, whereas biodegradable describes material breakdown under defined conditions. Therefore, a bio-based PA11 or PA610 grade should not be marketed as biodegradable unless the supplier provides relevant test data.