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Plastics & Elastomers
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Plastics & Elastomers
Polyamide (PA) or Nylon: Complete Guide (PA6, PA66, PA11, PA12…)

Beginner’s Guide to Polyamides (Nylons) and Beyond

Polyamides or nylons are considered high-performance plastics. They exhibit high temperature & electrical resistances. They find their use in the automotive, transportation, consumer goods, and E&E industry. Several types of polyamide chemistries are available in the market today based on:

    •    Monomeric units
    •    Polymerization chemistry

But are you finding it hard to select the right one for your specific application?

Make your selection process easy by elaborating on the types of polyamides. Key features and processing conditions of each class have been explained here. Also, understand what makes them an ideal choice in high-end engineering applications.

Find out the perfect polyamide or nylon polymer from 16000+ commercial grades present in our database.

Overview

Introduction to Polyamides

Introduction to Polyamides

Definition


A polyamide is a polymer containing repeating amide (–CO-NH–) linkages. They are high-performance engineering thermoplastics that occur either naturally or synthetically.

  • Naturally occurring polyamides are proteins
  • Synthetically occurring polyamides like nylons and aramids

Synthetic polyamides find use in automotive, transportation, electrical & electronics, consumer goods, etc.


History


Wallace Hume Carothers was the chemist behind the discovery of Polyamide and Nylon.

1928 – Hired by DuPont de Nemours to lead extensive research on the design of original polymeric materials.

1934 – Carothers and his team turned their attention to fibers to produce synthetic silk. In their experiments, they reacted a diacid and a diamine to form a polyamide polymer.

1935 – Dr. Gerard Berchet was assigned to this polyamide research. Under the direction of Carothers, they produced a half-ounce of polyamide 6-6.


Classification


The manufacturing of different polyamide types varies depending on the monomeric units.



Aliphatic Polyamides – Structure, Properties & Processing

Aliphatic Polyamides – Structure, Properties & Processing

Aliphatic polyamides (APs) are denoted by one or more numbers relating to the number of carbon atoms contained in the repeated pattern. Here is a list of the monomers used in the manufacturing of different aliphatic polyamides.

Aliphatic Polyamides Monomer(s)
Nylon 6 Caprolactum
Nylon 11 11-amino undecanoic acid
Nylon 12 Laurolactam
Nylon 6-6 Hexamethylene Diamine/ Adipic Acid
Nylon 6-9 Hexamethylene Diamine/ Azelaic Acid
Nylon 6-10 Hexamethylene Diamine/ 1,12-Dodecanedioic Acid
Nylon 6-12 Hexamethylene Diamine/ Sebacic Acid
Nylon 4-6 1,4-Diaminobutane/ Adipic Acid
Nylon 12-12 1,12-Dodecanediamine/ 1,12-Dodecanedioic Acid
Aliphatic Polyamide Polymers and Their Monomers


Structure of Polyamide 6 (Nylon 6)


Polyamide 6 (PA 6) is also known as Nylon 6 or polycaprolactam. It is one of the most extensively used polyamides globally. It is synthesized by ring-opening polymerization of caprolactam. Melting point of polyamide 6 is 223°C.

Polyamide 6
Molecular Structures of Polyamide 6


Structure of Polyamide 6-6 (Nylon 6-6)


Polyamide 6-6 (PA6-6) or Nylon 6-6 is one of the most popular engineering thermoplastics. It is majorly used as a replacement for metal in various applications. Nylon 66 is synthesized by polycondensation of hexamethylenediamine and adipic acid. These two monomers contain 6 carbon atoms each. Melting point of polyamide 6-6 is 255°C.

Polyamide 66
Molecular Structures of Polyamide 66


Main properties of PA 6 and PA 6-6


PA 6 & PA 6-6 are by far the most used polyamides globally. They are used in many applications due to their excellent performance/cost ratios. Their key properties include:

  • High strength and stiffness at high temperature
  • Good impact strength, even at low temperature
  • Very good flow for easy processing
  • Good abrasion and wear resistance
  • Excellent fuel and oil resistance
  • Good fatigue resistance
  • Good electrical insulating properties
  • High water absorption and water equilibrium content limit the usage
  • Low dimensional stability
  • Attacked by strong mineral acids and absorbs polar solvents
  • Proper drying before processing is needed

Although they exhibit similar properties, slight differences do remain.

See the detailed property comparison between PA6 and PA66
PA 6 vs. PA 6-6 PA 6-6 vs. PA 6
  • Slightly lower temperature resistance
  • Slightly less expansive
  • Excellent surface appearance
  • Better processability
  • Better hydrolytic stability
  • Better long-term heat aging
  • Similar stiffness at temperatures below 180°C
  • Low cost and heat deflection temperature
  • Slightly less moisture absorption ability
  • Higher modulus
  • Better wear resistance
  • Better short-term heat resistance


Processing conditions of PA6 and PA66


While processing PA 6 and PA 6-6 drying before is highly recommended. The moisture content should be a maximum of 0.2%. The maximum permissible drying temperatures lie in the range of about 80 to 110°C.

Polyamide 6 and Polyamide 6-6 are thermally stable up to 310°C. At temperatures above this leads to decomposition. The initial products formed are mainly carbon monoxide, ammonia, and caprolactam. While processing Polyamide 6 and 6-6 with injection molding and extrusion techniques, the following conditions are recommended.

Injection molding

  • L/D ratio of 18:22
  • The melt temperature should be between 240-270°C (PA 6) & 270-300°C (PA 6-6)
  • The mold temperature should be in the range of 55-80°C

Commercial Grades View injection molding PA 6 grades View injection molding PA 6-6 grades

Extrusion

  • Only highly viscous grades can be processed by extrusion
  • A three-section screw with an L/D ratio of 20-30 is recommended
  • The processing temperature during extrusion should lie between 240 and 270°C (PA 6) & 270 to 290°C (PA 6-6)

Commercial Grades View PA 6 extrusion grades View PA 6-6 extrusion grades


Polyamide 11 (Nylon 11)


Polyamide 11 (PA11) or Nylon 11 is a rare bio-based engineering plastic. Derived from renewable resources (castor plants). It is produced by the polymerization of 11-amino undecanoic acid.

Rilsan® is one of the first biosourced polyamide. Melting point of Polyamide 11 is 190°C.

Bio-based polyamide derived from renewable resources (castor plants)
Bio-based polyamide derived from renewable resources (castor plants)

Several properties of PA11 are similar to Polyamide 12 (PA 12). PA 11 comparatively offers superior thermal and UV resistance, low water absorption, and lower environmental impact. It displays good impact strength and dimensional stability.

Strengths Limitations
  • The lowest water absorption of all commercially available polyamides
  • Outstanding impact strength, even at temperatures well below the freezing point
  • Resistant to chemicals, particularly against greases, fuels, common solvents, and salt solutions
  • Outstanding resistance to stress cracking, aging, and abrasions
  • Low coefficient of friction
  • Noise and vibration damping properties
  • Fatigue resistant under high-frequency cyclical loading condition
  • Ability to accept high loading of fillers
  • Highly resistant to ionization radiation
  • High cost relative to other polyamides
  • Lower stiffness and heat resistance than other polyamides
  • Poor resistance to boiling water and UV
  • Proper drying before processing is needed
  • Attacked by strong mineral acids and acetic acid, and are dissolved by phenols
  • Electrical properties highly depend on moisture content

If you wish to know more about PA 11 processing conditions, Click Here »


Polyamide 12 (Nylon 12)


Polyamide 12 (PA 12) or Nylon 12 is a semi-crystalline thermoplastic. It has a similar performance to Polyamide 11. It can be derived from both petroleum and renewable sources. It is an expensive polymer compared to other polyamides.

Polyamide12
Molecular Structure of Polyamide 12

Key properties of PA 12


  • It possesses lower impact resistance but shows good resistance to abrasions and UV.
  • It has a lower water absorbency than PA 6, PA 6-6, and all other types of polyamides.
  • The PA 12 grade displays good dimensional stability and reasonable electrical properties.
  • PA 12 is ideal for applications where safety, durability, or reliability over time is critical.
  • PA 12's transparent grades are also available, allowing high flexibility in terms of design and creation.

Strengths Limitations
  • Lowest water absorption of all commercially available polyamides
  • Outstanding impact strength, even at very low temperatures
  • Good chemical resistance, particularly against greases, fuels, common solvents and salt solutions
  • Outstanding resistance to stress cracking
  • Excellent abrasion resistance
  • Low coefficient of friction
  • Noise and vibration damping properties
  • Good fatigue resistance under high-frequency cyclical loading condition
  • Expensive than other polyamides
  • Lower stiffness and heat resistance than other polyamides
  • Low UV resistance
  • Proper drying before processing is needed
  • Electrical properties highly depend on moisture content


PA 11 and PA 12: Unique features you should know


PA 11 and bio-sourced PA 12 demonstrate the following features:

  • Excellent chemical resistance
  • Flexibility
  • Durability
  • Cold impact resistance
  • Thermal resistance

PA11 PA12 Key Features


These properties give PA 11 and PA 12 an edge over traditional bio-based polymers.

  • Even if they do not over-perform in terms of temperature resistance (HDT, peak temperature...), they exhibit outstanding retention of performance over time.
  • Their remarkable long-lasting performance allows for their use in a wide range of conditions (temperature, pressure, chemical...).
  • PA 11 and PA 12 are particularly suitable when reliability over time is needed.


PA 11 & PA 12 processing conditions


Drying before processing is highly recommended: 6-12 h at 80-90°C. Target moisture content should be a maximum of 0.1%.

Injection molding

  • For the plasticating unit, a three-zone screw with an L/D ratio between 18 and 22 is recommended.
  • Melt temperature: 180 - 230°C 
  • Mold temperature: 30 - 100°C
  • A decrease in mold temperature very often eases de-molding but a decrease in crystallinity then occurs.

Commercial Grades View injection molding PA 11 grades View injection molding PA 12 grades

Extrusion

  • General temperature setting depends very much on the resins to be processed and the type of extrudate, thus a general recommendation can not be given.
  • Temperature in the first heating zone: ~ 200°C
  • Conventional three-zone screw with an L/D ratio of at least 24 is recommended.
  • Mixing and shear elements may be useful to increase the melt homogeneity.
  • Cooling of the feeding section is mostly required.

Commercial Grades View PA 11 extrusion grades View PA 12 extrusion grades


Polyamide 6-10 (Nylon 6-10)


Polyamide 6-10 (PA 6-10) is a semi-crystalline polyamide. It is produced by the polymerization of hexamethylene diamine with a dibasic acid i.e., sebacic acid. Melting point of polyamide 6-10 is 223°C.

Key features of PA 6-10


  • Exhibits lower water absorption when compared to PA 6 or PA 6-6
  • Has a lower brittle temperature than PA 6 or PA 6-6
  • Has good abrasion resistance and chemical resistance
  • Possesses lower strength and stiffness unlike PA 6-6
  • Drying before processing PA 6-10 is highly recommended
  • PA 6-10 is much stronger than PA 11, PA 12, or PA 6-12
  • Low coefficient of friction
  • Good electrical insulating properties
  • High resistance against high energy radiation (gamma and X-rays)

Polyamide 6-10 is used to manufacture insulators for the electrical market. This is because of its good insulating properties, heat resistance, and flame retardancy.

Limitations of PA 6-10


  • High mold shrinkage, and high cost compared to other low water absorption polyamides.
  • It is attacked by strong mineral acids and absorbs polar solvents.

Commercial Grades View injection molding PA 6-10 grades View PA 6-10 extrusion grades


Polyamide 4-6 (Nylon 4-6)


Polyamide 4-6 (PA 4-6) or Nylon 4-6 is manufactured by polycondensation of adipic acid and 1,4-diaminobutane. Diaminobutane is synthesized from acrylonitrile and HCN. Melting point of polyamide 4-6 is 295°C.

Key properties of PA 4-6


Excellent thermal performance with Polyamide46
PA46 mechanical properties
Excellent wear resistance with PA46
Chemical resistance with PA46
Excellent electrical resistance with PA46
Good Thermal
Performances
Good Mechanical
Properties

Particularly at high
temperatures
Excellent Wear
Resistance
Excellent Chemical
Resistance
Excellent Electrical
Resistance

PA 4-6 is the polyamide exhibiting the highest temperature resistance. Its HDT at 1.8MPA is 160°C, and 285°C when filled with 30% of glass fibers. PA 4-6's mechanical resistance is superior to PA 6-6's. Its fatigue resistance is 50 times that of PA 6-6.

  • PA 4-6 is often used to replace metal in demanding, high-temperature applications.
  • Due to PA 4-6's excellent mar and wear resistance, it is used in gear applications. It offers a combination of mechanical and constant performances at high temperatures. It also offers excellent tribological behavior and high fatigue resistance in this industry.
  • PA 4-6 can be metalized. It is also possible to color a part made of PA 4-6. However, the color resistance will depend on the behavior of the pigments at high temperatures.
  • Due to its high fluidity, PA 4-6 is a good solution for complex shapes and parts with thin walls.

Strengths Limitations
  • Outstanding stiffness, fatigue, and creep resistance, up to 220°C
  • Excellent abrasion and friction behavior
  • Very good flow for easy processing
  • Very low injection cycle time, due to its high crystallization rate
  • Excellent fuel and oil resistance
  • Good impact strength
  • Very low flash
  • Good electrical insulating properties
  • High resistance against high energy radiation (gamma and X-rays)
  • High water absorption and water equilibrium content
  • High-temperature processing, due to its high melting point
  • Low dimensional stability
  • Attacked by strong mineral acids and absorbs polar solvents
  • Proper drying before processing is needed
  • Darkens with exposure to high heat


Polyamide 4-6 processing conditions


Polyamides are hygroscopic and hence tend to absorb moisture when left in the open. It is therefore highly recommended to dry Polyamide 4-6 for 2-8 h at 80°C before processing. This ensures that hydrolytic degradation does not occur. Target moisture content should be a maximum of 0.1%. For critical applications, the recommended moisture content is 0.05% or less. In this case, it is recommended to pre-dry pellets 24-100 h at 80-105°C.

  • Polyamide 4-6 can be processed on standard reciprocating screw injection molding machines.
  • An L/D ratio of at least 20 is recommended.
  • Melt temperature should lie between 300-330°C
  • Mold temperature should be in the range of 60-120°C.
  • Polyamide 4-6 does not stick to the mold surface and has good ejection properties.


Semi-aromatic Polyamides or Polyphthalamides

Semi-aromatic Polyamides or Polyphthalamides

Polyphthalamides are formed by the reaction of aromatic acids with aliphatic diamines. They are produced using a combination of terephthalic acid and isophthalic acids. Polyphthalamide also known as PPA is a high heat resistance semi-aromatic polyamide.

Key features of PPA


With its low moisture pick-up, PPA shows excellent retention of performances in:

  • Harsh chemical environments, and
  • Extreme temperature conditions

They also show excellent stiffness and creep resistance.

Polyphthalamides have an aromatic structure. Due to this structure, it offers several superior performances compared to other polyamides. They offer:


Polyphthalamide resin features an excellent stiffness-to-cost ratio and a high strength-to-weight ratio. Both these properties are superior relative to PBT, PPS, PEI, PET, and PA 66.

Polyphthalamide is stronger and less moisture-sensitive. They have better thermal properties compared to:


Yet they are less ductile in comparison. Some impact grades are available.

Strengths Limitations
  • Very high stiffness and strength, compared to PA 6-6
  • Good heat, chemical and fatigue resistance
  • Low water absorption
  • Very low creep tendency
  • Good dimensional stability
  • Requires high processing temperatures (up to 350°C)
  • Requires good drying equipment
  • Not inherently flame retardant
  • Attacked by powerful oxidants, mineral acids, acetic acid and formic acid

Polyphthalamide injection molding processing conditions


  • Drying time and temperature: 2h at 120°C or at least 8h at 80°C
  • Holding the melt at temperatures above 350°C may result in polymer degradation which should be avoided.
  • A melting temperature of 320-345°C.
  • A mold temperature of 80-140°C.
  • Use a screw with an L/D ratio of 18-22 during the plasticizing phase.

Are you looking for injection molding polyphthalamides? Find out the complete list of injection molding PPA grades here.


Aromatic Polyamides or Aramids

Aromatic Polyamides or Aramids

Aromatic polyamides are also known as Aramids. They are obtained from the polycondensation of terephthalic acid with diamines. PA 6-3-T is one of the common examples of aromatic polyamide. It is amorphous and transparent in nature. Aramids can be processed at 280-300°C and are expensive. When compared to aliphatic polyamides, aromatic polyamides have:

  • better dimensional stability,
  • flame and heat resistance, and
  • higher strength

Among this large polymer family, several types of polyamides are particularly suited for given applications. The best choice depends on the set of performances needed as well as the economic constraints.

☆ The two most widely used PAs are by far PA 6-6 and PA 6. They are often extruded to manufacture fibers (textile industry), or films (packaging), or injection molded.

☆ The polyamides with the highest performances are PPA and PA 4-6. They are good candidates for metal replacement developments or very specific applications exposed to extreme conditions.

☆ Bio-based PA is also available. For instance, PA 11 is based on castor-oil chemistry.

Synthesis and Main Properties

Synthesis and Main Properties

Reaction chemistry


Several methods are involved in the production of polyamides:

Condensation polymerization


Diacids and diamines react together with the loss of water to form nylon polymers. The reaction proceeds until the polymer precipitates from the solution and the chains terminate. Examples include nylon 6-6.

Condensation Polymerization of Polyamides
Condensation polymerization of polyamides


Ring-opening polymerization


Involves opening cyclic monomers like caprolactam to form linear polyamide chains. Heat or catalysts initiate the reaction. It proceeds similarly to condensation polymerization. Examples include nylon 6 and nylon 6,12.

Ring opening polymerization of Polyamide 6
Ring-opening polymerization of PA 65


NOTE

→ Nylons like PA 6 and PA 12 are obtained by chain polymerization of lactum.
→ Nylons like PA11 are obtained by the polycondensation of an amino acid.
→ Nylons like (PA4-6, PA6-6, PA6-9, PA6-10, PA6-12, PA12-12) are obtained by polycondensation between a carboxylic acid and a diamine.

Key performance profile


Polyamides have a good balance of properties. They exhibit high temperature and electrical resistance. Thanks to their crystalline structure, they also show excellent chemical resistance. They have very good barrier and mechanical properties. These materials can easily be flame retarded.

Here are the main reasons why polyamides (nylons) are considered high-performance plastics:

Key Features Commercial Grades
Exceptional strength-to-weight ratio -
Heat and chemical resistance View PA grades with high heat resistance
View PA grades with good chemical resistance
Durability and Toughness View durable PA grades
View PA grades with good toughness
Dimensional stability View PA grades with good dimensional stability
Processability View PA grades with good processability

These properties position them above widespread commodity plastics for advanced engineering applications. Their unique property combination makes them exemplary high-performance thermoplastics.


Key Properties

Key Properties

Property PA 6 PA 66 PA 11/12 PA 46 PA 6/10 PPA
Chemical Resistance
Dioctylphtalate @ 100%, 60°C - - Satisfactory - - -
Ethanol @ 96%, 20°C - - Satisfactory - - -
Glycerol @ 100%, 20°C - - Satisfactory - - -
Grease @ 20°C - - Satisfactory - - -
Hydrogen peroxide @ 30%, 60°C - - Non Satisfactory - - -
Kerosene @ 20°C - - Satisfactory - - -
Methanol @ 100%, 20°C - - Satisfactory - - -
Methylethyl ketone @ 100%, 20°C - - Satisfactory - - -
Mineral oil @ 20°C - - Satisfactory - - -
Phenol @ 20°C - - Non Satisfactory - - -
Silicone oil @ 20°C - - Satisfactory - - -
Soap @ 20°C - - Satisfactory - - -
Sodium hydroxide @ <40%, 20°C - - Satisfactory - - -
Sodium hydroxide @ <40%, 60°C - - Limited - - -
Sodium hydroxide @ 10%, 20°C - - Satisfactory - - -
Sodium hydroxide @ 10%, 60°C - - Limited - - -
Sodium hypochlorite @ 20%, 20°C - - Limited - - -
Toluene @ 20°C - - Satisfactory - - -
Xylene @ 20°C - - Satisfactory - - -
Gasoline - - Satisfactory - - -
Acetone @ 100%, 20°C - - Satisfactory - - -
Ammonium hydroxide @ 30%, 20°C - - Satisfactory - - -
Benzene @ 100%, 20°C - - Limited - - -
Butylacetate @ 100%, 20°C - - Satisfactory - - -
Butylacetate @ 100%, 60°C - - Satisfactory - - -
Chloroform @ 20°C - - Non Satisfactory - - -
Dioctylphtalate @ 100%, 20°C - - Satisfactory - - -
Electrical
Arc Resistance, sec 118-125 130-140 - - 120 -
Dielectric Constant 4-5 4-5 - 3.4-3.8 3-4 4.3
Dielectric Strength, kV/mm 10-20 20-30 - 15-25 16-26 20.8-209
Dissipation Factor x 10-4 100-600 100-400 - 190-600 40 270
Volume Resistivity x 1015, Ohm.cm 14 14 - 15 14 15
Mechanical
Elongation at Break, % 200-300 150-300 - 160-300 150-300 2.6-30
Elongation at Yield, % 3.4-140 3.4-30 - - - 6
Flexural Modulus, Gpa 0.8-2 0.8-3 - 1-3.2 1-2 2.1-3.7
Hardness Rockwell M 30-80 30-80 - 92 1-50 -
Hardness Shore D 80-95 80-95 - - 60-85 -
Strength at Break (Tensile), MPa 50-95 50-95 - 65-85 50-65 85
Strength at Yield (Tensile), MPa 50-90 45-85 - 65-85 50-65 -
Toughness (Notched Izod Impact at Room Temperature), J/m 50-160 50-1150 - 30-250 70-999 960-1065
Toughness at Low Temperature (Notched Izod Impact at Low Temperature), J/m 16-210 27-35 - - - -
Young's Modulus, GPa 0.8-2 1-3.5 - 1-3.3 1-2 3.7
Optical
Gloss, % 130-145 65-150 - - - -
Physical
Density, g/cm3 1.12-1.14 1.13-1.15 - 1.17-1.19 1.09-1.1 1.11-1.2
Glass Transition Temperature, °C 60 55-58 - - - -
Shrinkage, % 0.5-1.5 0.7-3 - 1.5-2 1-1.3 1.5-2.2
Water Absorption 24 hours, % 1.6-1.9 1-3 - 1.3-3.7 0.4-0.6 0.36-0.75
UV Light Resistance Fair Poor Fair - Fair -
Sterilization Resistance (Repeated) Poor Poor - - - Good
Gamma Radiation Resistance Fair Fair Fair Fair Fair Good
Service Temperature
HDT @0.46 Mpa (67 psi), °C 150-190 180-240 - - 160-175 -
HDT @1.8 Mpa (264 psi), °C 60-80 65-105 - 150-155 80-85 120-138
Max Continuous Service Temperature, °C 80-120 80-140 - 110-150 80-150 140
Min Continuous Service Temperature, °C -40--20 -80--65 - -40 - -
Thermal
Coefficient of Linear Thermal Expansion x 10-5, /°C 5-12 5-14 - - 6-10 5.4
Thermal Insulation, W/m.K 0.24 0.25 - 0.3 0.21 -
Fire Resistance (LOI), % 23-26 21-27 - 24 23-27 -
Flammability, UL94 HB HB HB, V2 HB V2 HB
Physical Forms and General Processing Techniques

Physical Forms and General Processing Techniques

Forms of nylon grades


Nylons are available in several physical forms:

Pellets


Nylon pellets are the most common form with sizes between 2mm to 5mm in diameter. They are shaped like small cylinders or discs. They are melted and molded into finished plastic parts or extruded into filaments/fibers.

Powder


Nylon powders have an average particle size ranging from 10 to 200 microns. Used in rotational molding, powder coating, and selective laser sintering applications to create 3D objects. The powder melts and fuses when heat is applied.

Granules


Slightly larger than pellets, Nylon granules measure approximately 4mm to 8mm across. They improve material flow ability and are convenient for feeding into extrusion machinery compared to fine powders.

Solid


Custom polymer shapes can be machined from nylon blocks, rods, or plates. Common solid forms are round rods, rectangular blocks, and discs. Dimensions range from a few centimeters up to multiple meters long.

Chips


Flakes or angular irregularly shaped pieces with a broad size distribution are referred to as nylon chips. They may be recycled polymer feedstock or skeletal powder residues. Chips may be blended back into the molding process.

In summary, Nylons offer versatility in physical design to suit many manufacturing processes. The form dictates the optimal fabrication conditions to produce the desired nylon products.

Discover the various forms of nylon grades available in our database.

Nylon pellets Nylon powders Nylon granules Nylon solids Nylon chips


Conversion modes


Nylons can be processed by all common melt processing techniques. Though low melt viscosity Nylons need particular attention. Due to their semi-crystalline nature, one must control the processing of Nylons. This is done to optimize the physical properties of the end component.

Thanks to their crystalline structure Nylons are easy to inject, showing high fluidity. This is particularly appreciated when injecting thin-walled parts.

Due to their moisture sensitivity, Nylons need an efficient drying process. Insufficient drying will lead to splays and unaesthetic marks on part surfaces. They lower the mechanical properties due to material degradation. This degradation by heat and water leads to oxidation.

Injection molding


All Nylon materials can be processed by injection molding.
  • If the moisture content is >0.2%, drying in a hot air oven at 80°C (176°F) for 16 hours is recommended. If the material has been exposed to air for more than 8 hours, vacuum drying at 105°C (221°F) for more than 8 hours is recommended. 
  • Mold Temperature: 60-80°C
  • Melt Temperature: 230 - 280°C; 250 - 300°C for reinforced grades
  • Material Injection Pressure: 75 - 125 MPa (depends on material and product design)



Extrusion


Nylons can be processed by extrusion.
  • Maximum allowable moisture content 0.1%
  • Melt Temperature: 230-290°C
  • The compression ratio: <4.0
  • The L/D Ratio: 25-30 (Barrier Screw or Polyolefin Screw with equal feed, transition and metering section)


3D printing


Nylons are also widely used to produce 3D parts printed by selective laser sintering (SLS). 3D printing techniques used to produce plastic prototypes offer several benefits such as the production of complex parts, individual designs, and cost-effectiveness in small-scale production.


An Interesting Video on Tips and Tricks for Nylon 3D Printing


Find out the conversion modes of nylon grades available in our database.

Injection molding nylon Extruded Nylon Grades 3D Printing Nylon Grades


Modification and Functionalization

Modification and Functionalization

How do additives tailor polyamide properties?


Various additives are incorporated into polyamides to tailor specific properties and performance characteristics.

Plasticizers


They improve the flexibility and processability of otherwise rigid polymers. Phthalates and oligomeric plasticizers penetrate polyamide chains, increasing free volume, and chain mobility.

All polyamides tend to absorb moisture due to the amide chemical group. The moisture acts as a plasticizer. This thus reduces tensile modulus and increases impact resistance & flexibility. Moisture uptake also has a huge influence on dimensional variations. It must be taken into account when designing parts.


Impact modifiers


Impact modifiers also enhance toughness and resistance to fracture. For example, maleic anhydride grafted ethylene-propylene rubber.


Lubricating additives


Lubricants reduce viscosity and improve flow during processing. For example, ethylene bisstearamide and other fatty acid derivatives facilitate resin flow.


Flame retardants


Flame retardants increase fire resistance. Halogenated and non-halogenated retardants promote char formation or emit gases to slow burning.


Other additives


Additives change the appearance, feel, and cost of polyamide formulations. Other additives include colorants, slip agents, and fillers.

For example, when reinforced with glass fibers, their stiffness can compete with metals. These glass fibers can be short or long. This is why Polyamides are often considered in metal replacement projects.


Effect of nanomaterials


The fillers most used for polyamides are:

  • Montmorillonite (MMT)
  • Bentonite vermiculite
  • Sepiolite
  • Halloysite
  • Modified MMT (oMMT)
  • Carbon black (CB)
  • Graphene (G) 
  • Graphene oxide (GO)
  • Carbon nanotubes (CNT)
  • Single-walled CNT (SWCNT)
  • Multi-walled carbon nanotube (MWCNT)
  • Carbon fibers (CF)
  • Glass fibers (GF)
  • Metallic and alloy powders, etc. 

  1. CNTs have attracted researchers’ attention as an ideal filler due to their very good contribution to the mechanical, thermal, and electrical properties of polymer nanocomposites.1

  2. The effect of surface modification of MWCNT on the mechanical and tribological properties of PA 66/MWCNT nanocomposites was investigated. Amine functionalization of the nanofiller increased:
    • the polarity of the surface,
    • the interaction matrix-filler,
    • the degree of crystallization,
    • the melting enthalpy, and
    • the mechanical properties
    A thin film on the contact surfaces played an important role both in reducing wear and friction and in suppressing cracks when the two composites' discs ran against each other.2

  3. PA 11/MMT with guanidinium functionalized POSS showed superior mechanical and thermal properties for MMT modification. This is attributed to the strong interaction between guanidinium and MMT.3


Sustainability Aspect of Polyamides

Sustainability Aspect of Polyamides

Can polyamides be recycled?


The key use of nylon 6 is in carpets. A recycling process for this was initially devised by DuPont in 1944. Although recycling a dirty carpet is still a challenge.

Nylon polymer can be chemically recycled or de-polymerized

De-polymerization method involves breaking down the long polymer chains into monomers. These monomers can be then re-polymerized. This converts the waste into products having a quality equal to the “virgin” polymer.

For example, Nylon 6 can be depolymerized to its monomer – caprolactam by:

  • Acidolysis
  • Hydrolysis
  • Aminolysis, or
  • Catalyzed-de-polymerization in vacuum

Are you looking for companies that supply recycled nylon? Check out the complete range of recyclable nylon grades »

Other methods include the recovery of polymer components without reaching the monomer level. These recycling methods include:

  • Multiple extraction and separation steps
  • Mechanical recycling
  • Thermal recycling, or
  • Energy generator

Polyamide Recycling from Carpets
(Source: AlliedSignal/NCSU)


Are polyamides biodegradable?


Polyamides are considered to be nonbiodegradable polymers. This is due to the strong molecular chain interactions, less polarity than proteins, and high crystallinity. However, they can be made biodegradable to varying extents by:

Introduction of hydrolytically unstable bonds


By copolymerizing monomers with ester, glycosidic, or peptide bonds along with amide groups. The resulting nylon structure becomes susceptible to enzyme-catalyzed hydrolytic cleavage. This accelerates breakdown in the environment.

Blending with biodegradable fillers


Adding biofillers makes nylons more accessible to microbial or enzymatic attacks during degradation. Some examples of biofillers include starch, cellulose, or lignin.

Synthesis from bio-based monomers


Polyamides derived from naturally occurring amino acids, vegetable oils, or microbial sources tend to degrade more readily. Certain aliphatic polyamides are susceptible to biodegradation by microorganisms.

PA Types

Microorganisms

Conditions

Bacteria

PA 6

Bacillus cereus

pH 7.5 temp. 35°C, mineral salt medium under submerged enrichment conditions with the polymer as the sole carbon source, 31% molar mass decrease (Mn0 = 58,000), moieties formed in 90 days: NHCHO, CH3, C(O)NH2, CHO, and COOH

Bacillus sphericus, Vibrio furnisii, Brevundimonas vesicularis

pH 7.5 temp.35°C, mineral salt medium under submerged enrichment conditions with the polymer as the sole carbon source, less than 10% molar mass decrease (Mn0 = 58,000), moieties formed in 90 days: NHCHO, CH3, C(O)NH2, CHO, and COOH

Neighboring species to Bacillus pallidus, strain 26

pH 7.0, temp. 60°C, molar mass decrease in 20 days (Mv0 = 39,000), strain 26 recognized an amide linkage based on ω-amino acid

PA 12

Neighboring species to Bacillus pallidus, strain 26

pH 7.0, temp. 60°C, molar mass decrease in 20 days (Mv0 = 41,000), strain 26 recognized an amide linkage based on ω-amino acid

Geobacillus thermocatenulatus

pH 7.0, temp. 60°C, 73% molar mass decrease in 20 days (Mv0 = 41,000)

PA 6-6

Geobacillus thermocatenulatus

pH 7.0, temp. 60°C, 60% molar mass decrease in 20 days (Mv0 = 43,000)

Bacillus cereus

pH 7.5, temp. 35°C, mineral salt medium under submerged enrichment conditions with the polymer as the sole carbon source, 42% molar mass decrease (Mn0 = 55,000), moieties formed in 90 days: NHCHO, CH3, C(O)NH2, CHO, and COOH

Bacillus sphericus, Vibrio furnisii, Brevundimonas vesicularis

pH 7.5, temp. 35°C, mineral salt medium under submerged enrichment conditions with the polymer as the sole carbon source, less than 10% molar mass (Mn0 = 55,000), moieties formed in 90 days: NHCHO, CH3, C(O)NH2, CHO, and COOH

Fungi

PA 6

Phanerochaete chrysosporium

pH 6.25, temp. 30°C, 50% molar mass decrease in 90 days (Mn0 = 16,900)

PA 6-6

Trametes versicolor

Temp. 30°C, nitrogen starvation, 68% molar mass decrease (Mw0 = 85,000), moieties formed in 20 days: CHO, NHCHO, CH3, and C(O)NH2, degradation through oxidation by peroxidase

White rot fungi, IZU-154

Temp. 30°C, nitrogen or carbon starvation, 93% molar mass decrease in 20 days (Mw0 = 85,000), CHO, NHCHO, CH3, and C(O)NH2, degradation through oxidation by peroxidase

Phanerochaete chrysosporium

Temp. 30°C, nitrogen starvation, 86% molar mass decrease in 20 days (Mw0 = 85,000), CHO, NHCHO, CH3, and C(O)NH2, degradation through oxidation by peroxidase

Selected microorganisms degraded PA 6, PA 12, and PA 6-64


Are polyamides good or bad for the environment?


When it comes to their environmental impact, polyamides have some pros and cons.

Pros


  • They are durable and long-lasting plastics. Hence, products made from nylons don’t need to be replaced often.
  • They can often be recycled. Giving materials a second life by sending them to landfills.

Cons


  • Nylons are made from petroleum. Its production requires extensive energy and generates a lot of nitrous oxide. This can lead to significant greenhouse emissions.
  • Recycling rates for nylons are quite low globally. So, a lot of nylon products end up in landfills and oceans.

The best options to minimize their environmental footprint are by reducing their use, reusing products, and recycling at end-of-life. Biobased and biodegradable nylons are also being developed to help address some of these issues.


Are polyamides safe to use?


Polyamides are considered safe for most applications.

  • Raw materials used in the preparation of nylons may be hazardous. These substances include strong acids and gases that are involved during the complete production process. But in finished consumer products, they are risk-free.
  • Food-grade nylons comply with EU and FDA food contact regulations. They show no migration of harmful substances in food packaging.
  • Medical grade nylons show excellent biocompatibility. Used in implantable devices that do not break down or leach harmful compounds into the body over time.
  • Nylons can begin to decompose when exposed to very high temperatures (above 500°F).

Checking regulations and following product instructions given by the supplier is advisable when using nylon materials.


Nylon vs Polyester - Key Differences You Should Know

Nylon vs Polyester - Key Differences You Should Know

Both nylon and polyester are thermoplastic materials. But polyester compounds can be thermosets as well. They both are majorly synthetic in nature. Their main differences are listed in the table below.

Nylon Polyester
Type Thermoplastic Polymers commonly known as Polyamides Thermoplastic or Thermoset
History First Nylon was produced by Wallace Carothers in 1935 First polyester fiber called Terylene created in 1941
Production Nylon is formed by the condensation of copolymers. Equal parts of dicarboxylic acid and diamine are used for the process. There are peptide bonds on the ends of the monomers Synthetic polyesters are made up of dimethyl ester dimethyl terephthalate (DMT) or the purified terephthalic acid (PTA).
Uses Used in apparel, flooring, molded parts for cars, electrical equipment, etc., packaging films Used to manufacture a variety of products, including textiles, belts, furniture, insulation, padding, tarps and glossy finishes for hardwoods
Touch A silky, smooth touch Fiber feeling
Durability Exceptionally strong, abrasion resistant, resistant to damage from oil and many chemicals Strong, resistant to stretching and shrinking, resistant to most chemicals, crisp and resilient wet or dry, abrasion resistant
Stretchability Low moisture absorbency allows fabric to stretch No water absorbance, faster drying, wrinkle resistant
Commercial Grades Nylon Grades Polyester Grades


References

  1. Feldman, Dorel (2017). Polyamide nanocomposites. Journal of Macromolecular Science, Part A, 54(4), 255–262.
  2. Qiu, L., Yang, Y., Xu, L., Liu, X. (2013) Polym. Compos, 34: 656–664.
  3. Wang, S., Sharma, M., Leong, Y. W. (2015) Adv.Mat.Res., 1110: 65– 68.
  4. Kyulavska, M., Toncheva-Moncheva, N., & Rydz, J. (2019). Biobased Polyamide Ecomaterials and Their Susceptibility to Biodegradation. Handbook of Ecomaterials, 2925–2926.
  5. Dubois, Philippe; Coulembier, Olivier; Raquez, Jean-Marie (2009). Handbook of Ring-Opening Polymerization, 166.

Key Applications

Suppliers

Brands

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