Introduction
- In the blown film extrusion industry, the selection of packaging materials is very important, especially when it comes to barrier films. Barrier films are those that block oxygen, moisture, or gases and increase the shelf life of products. Two materials are very popular for making barrier films: nylon and EVOH.
- Nylon, also known as polyamide, is known for its strength and flexibility, while EVOH (ethylene vinyl alcohol) is most commonly used for its oxygen barrier properties. But what are the differences between these two materials? When should nylon be used and when EVOH? These questions often arise in the packaging industry.
- In this blog post, we will understand the key differences, properties, and applications between Nylon and EVOH in detail. Whether you are into food packaging or industrial applications, this information will help you choose the right material. So, let’s get started!
What is Nylon?
- Nylon, also called polyamide (PA), is a synthetic polymer made from petroleum products. It is a strong, durable, and versatile material that was developed by DuPont Company in the 1930s. Nylon is used in many industries today, such as textiles, automotive, packaging, and industrial applications.
Table of Contents
Types of Nylon:
There are many types of nylon, but these two nylons are most commonly used in industry. The two most commonly used nylons in industry are as follows:
- Nylon 6: Nylon 6 is made from caprolactam and hence has good flexibility and toughness.
- Nylon 66: Nylon 66 is made from hexamethylenediamine and adipic acid. Nylon 66 is stronger and more heat-resistant than Nylon 6.
Note: Read more about Nylon 66 and Nylon 6.
Key Properties of Nylon:
- High Strength: Nylon is very strong and tough, which makes it perform well in puncture and tear resistance.
- Flexibility: It is flexible, which makes it easy to process in blown film extrusion. This makes it used in both thin and thick films.
- Barrier Properties: Nylon is good at blocking oxygen and aroma, but its oxygen barrier performance is lower than EVOH.
- Moisture Resistance: Nylon is also a moisture barrier, but it can absorb humidity, due to which its properties may change slightly.
- Thermal Stability: Nylon has a high melting point (220–260 °C), which makes it suitable for high-temperature applications.
Applications of Nylon:
- Packaging: Nylon is used in vacuum bags, pouches, and heavy-duty packaging.
- Automotive: Nylon is used to make fuel lines, gears, and engine components.
- Textiles: Nylon is used to make clothing, ropes, and carpets.
- Industrial: Nylon is used to make bearings, seals, and mechanical parts.
Limitations of Nylon:
As the use of nylon is increasing, it also has some limitations, which are as follows:
- Cost: Nylon is more expensive than polyolefins (such as PE and PP).
- Moisture Absorption: It can absorb humidity, which can affect its mechanical properties.
- Processing: It needs to be dried before processing, otherwise it can degrade.
What is EVOH?
- EVOH, which stands for ethylene vinyl alcohol, is a high-performance synthetic polymer produced by copolymerization of ethylene and vinyl acetate. It is an exceptional barrier material, especially useful in blocking oxygen and other gases. Due to its excellent barrier properties, EVOH is highly preferred in the packaging industry, especially where oxygen may harm the quality of products.
Key Properties of EVOH:
- Excellent Oxygen Barrier: EVOH is one of the most useful materials for blocking oxygen. It is ideal for extending the shelf life of products in food and medical packaging.
- Humidity Sensitivity: The barrier properties of EVOH depend on humidity. In high humidity, its oxygen barrier performance is reduced.
- Clarity and Gloss: EVOH films are transparent and glossy, making packaged products look attractive.
- Chemical Resistance: It provides good resistance against oils, solvents, and chemicals.
- Thermal Stability: The melting point of EVOH is between 160–190°C, making it suitable for blown film extrusion.
Nylon vs EVOH
When it comes to blown film extrusion and packaging applications, both Nylon and EVOH materials are known for their unique properties. Here we will compare the key properties of these two materials to help you understand which material will be better suited to your requirements.
- Nylon: Nylon needs to be dried before processing. It is processed at high temperatures and is used as the outer or middle layer in multi-layer films.
- EVOH: EVOH also needs to be dried. It is used as the middle layer so that it does not come into contact with moisture.
Propertiese | Nylon | Evoh |
Oxygen Barrier | Good | Excellent |
Moisture Barrier | Good | Poor |
Mechanical Strength | High | Modrate |
Flexibility | Flexible | brittle |
Melting Point | 220–260°C | 160–190°C |
Chemical Resistance | Excellent | Excellent |
Cost | Moderate | High |
When to Choose Nylon?
- When you need mechanical strength and a moisture barrier, nylon material will prove to be useful.
- When it comes to heavy-duty applications such as vacuum packaging, pouches, and industrial bags, nylon material proves to be useful.
- When the oxygen barrier is important but you do not need as high performance as EVOH, you can use nylon material.
When to Choose EVOH?
- When oxygen barrier is the highest requirement, evoh is used as it has the best oxygen barrier properties compared to nylon and other materials.
- When it comes to food packaging where an oxygen barrier is necessary to increase the shelf life of products, evoh is used.
- Evoh is also used for specialized applications like medical packaging and fuel tanks when cost is not a major issue.
Conclusion
- Both Nylon and EVOH materials play an important role in the packaging industry, with their own strengths and limitations. Nylon is better for mechanical strength and versatility, while EVOH is most commonly used for oxygen barrier and clarity.
- Choose the right material based on your application requirements, environmental conditions (such as humidity), and budget. If you need to combine the properties of both materials, using Nylon and EVOH together in multi-layer films can be a good option.
Pingback: Thermal Properties Of Materials: Key Factors In Heat Resistance & Conductivity
Pingback: Pancake Vs. Stacked Die System In Blown Film Extrusion: Key Differences & Applications