What is Nylon?
Nylon is a linear thermoplastic, also known as Polyamide. It is a strong, high-performance, engineering plastic with excellent tensile strength which is often seen as an alternative to silk, rubber, and latex. It is a commonly used thermoplastic material for various applications like clothing, rubber components like tires, ropes, threads, automobile parts, mechanical components, etc.
Polyamide or Nylon was first developed and tested in 1935 by an American chemist named Wallace Carothers. What Wallace produced was technically Nylon 66, which is still the most commonly used variant.
It is solid, abrasion, chemical, and moisture absorptive, elastic, and long-lasting. Nylon material is often used as an alternative to low-strength metals for its lightweight compared to metals, chemical suitability, good mechanical and barrier properties, and high-temperature resilience.
Additionally, nylon can easily be flame retarded which is quite rare to be found in thermoplastics.
Different Types of Nylon –
Nylon is available in white, black, and off-white colours. There are multiple types of nylon in the larger polyamide family, and each one of them is utilized depending on the application and the budget restrictions.
It is also referred to by its chemical name – PA (e.g., PA6, PA66 )
“6” means that the material is conceived with a single monomer in combination with itself. In comparison, “66” shows that the material is conceived from multiple monomers combined with itself ( also called comonomers ).
- The two most commonly known and used Nylon types are PA66 ( Nylon 66 ) and PA6 ( Nylon 6 ). They are often extruded to be used in the textile and packaging industries.
- The two most rigid and high-performance-based nylon variants are PPA and PA46, which are considered great options for replacing metals. They are used for products constantly exposed to extreme conditions and particular high-end applications.
- There are many Bio-based variants; for example – PA11 is extracted using castor oil chemistry.
The amide chemical group present in all the nylon variants is responsible for moisture absorption. Moisture reduces nylons’ tensile modulus, increasing smack resistance and pliability.
Moisture absorption is also a key to understand dimensional variations. Knowing that will come in handy while designing parts.
How is Nylon Made?
The process is similar to other plastics; it all starts with filtering hydrocarbon fuels into lighter groups called fractions.
A certain amount of fractions are removed and combined with other catalysts to produce plastics (typically via polymerization or polycondensation).
The original method for producing nylon falls under two different processes.
The first process includes blending a group of monomers amine (NH2) groups reacting with carboxylic acid (COOH).
In the second method, the same molecules will be used in the multiple of 2. That means a reaction of diamine ( 2 x NH2 groups) with dicarboxylic acid ( 2 x COOH groups).
Differentiation: PA6 and PA66 –
|It is manufactured and synthesized using ring-opening polymerization of caprolactam.||
On the other hand, Nylon 66 is manufactured and synthesized by polycondensation of hexamethylenediamine and adipic acid.
|It is extensively used in the packaging and textile industries.||
It is widely recognized as an engineering thermoplastic and utilized as a lightweight replacement for metals.
|Melting Point – 223°C||
The melting point – is 255°C.
|Less moisture absorption ability compared to Nylon 66||
High Moisture absorption ability and better short term heat resistance
Higher Modulus and better wear resistance
Key Properties of PA6 and PA66 –
- Fantastic fuel and oil resistance
- Impressive electrical insulating properties
- Low dimensional stability
- Great impact strength ( even at low temperatures )
- Proper dyeing is a must before processing
- Decent fatigue resistance
- Key weaknesses – mineral acids and polar solvents
- High strength and stiffness at relatively high temperature
Below are the typical properties of various grades of Nylon:
Extruded NYLON 6/6
Cast NYLON 6
Oil-Filled Cast NYLON 6
|Flexural modulus||psi||D790||410,000||420,000 – 500,000||
375,000 – 475,000
|Tensile Strength||psi||D638||12,400||10,000 – 13,500||9,500 – 11,000|
|Heat deflection temperature – 264 psi||°F||D648||194||200 – 400||200 – 400|
|Water absorption (immersion 24 hours)||%||D570||1.2||0.60 – 1.20||0.50 – 0.60|
|Maximum continuous service temperature in air||°F||–||210||230||230|
|Coefficient of linear thermal expansion||in/in/°Fx10-5||D696||4.5||5||5|
|Izod Impact||ft-lbs/in of notch||D256||1.2||0.7 – 0.9||1.4 – 1.8|
Advantages of Nylon –
- Nylon is super lightweight compared to other thermoplastic materials. The weight is almost 1/7 of the materials.
- Both the grades have a high tensile and compressive strength.
- Great wear-resistance and abrasion.
- Fantastic dust and dirt resistance (Not easy to found in other materials).
- Smooth processing and easy machining.
- Complex designs are achievable.
Disadvantages of Nylon-
- Highly flammable. Catches free quickly in an open flame.
- High melting temperature.
- Negative impacts of UV exposure. A UV stabilizer is often added before processing.
Challenges Faced While Molding with Nylon –
Like any other thermoplastic, some challenges are often faced while processing Nylon. Let’s discuss them in brief.
Nylon is one of the most hygroscopic material, means it easily absorbs excess moisture, which can sometimes be a headache. Draining should be done properly and promptly.
Poor drying can lead to excess gassing and other potential scrap generating defects.
Although, excess moisture is easily avoidable by cleaning the loader line and loader receptacle properly.
Nylon is a bit vulnerable to shrinkage problems during the molding process. Shinkage can cause reduced strength, discoloration, and warped edges in the final product.
Controlling the heat and molding temperature can reduce shrinkage significantly.
Excess gassing can have significant defects in nylon plastic. In addition, a poor pale appearance is common with excess gassing.
High mold temperature and poor venting is the most common reason of gassing.
Prevention of gassing is actually quite simple; just finding the right temperature for processing and adding an extra vent in the machine can eradicate gassing completely.
Both PA6 and PA66 are extensively utilized in multiple industries for numerous products like safety and comfort gears, electronics, sports, leisure, etc.
- Electrical & Electronics
- Food Packaging
- Consumer Products
- Furniture Industry
#1 Electrical and Electronics:
Both PA 6 and PA66 grades are qualified enough to be used for electrical and electronics products. If they pass GWIT, UL94 test, their application in your products will become easier.
Both the grades can easily be flames retarded. That gives it a tremendous advantage to be used in electrical products with miniatures and thin designs are required.
#2 Food Packaging:
Excellent puncture resistance is one of the main features of PA6 and PA66. Along with that, good barrier resistance to oxygen, carbon dioxide, and other gases.
These properties are a must for food packaging applications. That makes PA6 and PA66 highly suitable for providing safe, secure, and most importantly, safe for compatible human-contact packaging solutions (mono and multilayer ).
Good Processability, wonderful chemical and temperature resistance makes PA6 and PA66 suitable for replacing metal in automobiles (Mostly under the hood parts where design pliability is very important).
Their major contribution is towards weight savings which helps in reducing Co2 emissions and improving the safety and comfort of automobiles.
#4 Consumer Products:
polyamide 66 has numerous applications for the consumer goods industry thanks to its properties like mechanical resistance, easy shaping, colorability, a decent surface aspect crucial for consumer goods.
PA66 is easy to use and inexpensive compared to a lot of thermoplastics used for the application. Even shaping the goods in complex designs is doable.
Traditionally, polypropylene was the popular thermoplastic for furniture application (and it still is). However, firms are steadily transitioning to Nylon.
It is actively being utilized for manufacturing home and office furniture, stadium seats, etc.
Brilliant surface finish quality, excellent resistance to dirt, and ageing have played a huge role in bringing Pa6 and PA66 into mainstream furniture manufacturing.
The Future of Nylon in Plastics Industry –
According to studies conducted by fortune global insights global Nylon market size is pegged to grow about USD 30 Billion by 2026.
As the demand for sustainable polymeric products is on a high trajectory, nylon plays an important role in developing such products.
For example, Osprey, a manufacturer of outdoor products, partnered with Hyosung in August 2020 to utilize its 100% recycled fiber for manufacturing outdoor products. Similarly, a french company named Longchamp is making bags from waste nylon.
However, in the short term, the demand is hampered significantly because of the COVID-19 outbreak resulting in economic uncertainty worldwide. Things will take time to come back to normal. Still, in the longer term, Nylon’s irreplaceability in industries like textile and automobiles gives it an edge to stay relevant even in tough times.
1. Why is Nylon so strong?
Ans. The main fibre composition is a strong synthetic polymer that makes its bonds tight, making nylon rigid and strong.
2. Does Nylon has an extended structure?
Ans. Nylon and silk have a very similar structure but have different degradation processes. H-bonds join neighbouring chain segments and create an extended planar sheet such that NH groups can form strong hydrogen bonds (H-bonds) with the CO group, which causes a crystal structure of nylon. That means it doesn’t have an extended structure.
3. Why does Nylon 6 have a high melting point?
Ans. The monomer of Nylon 6 is called aminocaproic acid, but in its ring form, it is known as caprolactam. When the ring is opened, the chemical will react with itself to produce the Nylon 6 polymer. The amide group of polymer are responsible for Nylon’s relatively high melting point and affinity for moisture.
4. Which is more water-resistant? Nylon or Polyester
Ans. Polyester is more water-resistant than Nylon. However, none of them is completely waterproof, Nylon has a moisture regain the level of 4%, and polyester has a moisture regain the level of 0.4%. Meaning, polyester is more hydrophobic than Nylon.
5. How do you clean Nylon Plastic?
Ans. It is quite easy to clean, but it should be done carefully because nylon resists absorbing moisture and dries easily. Handwashing is the easiest and safest way to clean Nylon products. Rinsing with cool water until the water is no longer soapy and don’t wring.
The Takeaway –
Thus, were my thoughts on nylon plastics. I have highly emphasized that both the common grades PA6 and PA66 are highly beneficial for any plastic manufacturing firm.
As it’s inexpensive compared to other plastics, it can play a vital role in bringing down your costs, thereby boosting profits without hurting the production quality.
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