What are the physical properties of EVOH EW-3201?

In modern industry, especially in the food, medical, and cosmetic packaging sectors, the requirements for material performance are becoming increasingly stringent. High-barrier materials are crucial for ensuring product quality, extending shelf life, and reducing waste. Ethylene-VinylAlcohol Copolymer is seen as a great green packaging material because it blocks gases, smells, and solvents so well. It also possesses good processability, transparency, mechanical strength, abrasion resistance, and cold resistance.

EVOH is a type of thermoplastic resin made from ethylene and vinyl alcohol. A key feature is the many hydroxyl groups (-OH) in its structure. These groups create strong hydrogen bonds, which limit how well gas molecules, like oxygen, can pass through it. This gives EVOH very good barrier properties. It blocks oxygen much better than common polymers like polyethylene (PE) or polypropylene (PP). In fact, EVOH can be thousands of times better at blocking oxygen.

1.  EVOH EW-3201: Specifications Overview

2. In-depth Analysis of Key Physical Properties

2.1 Superior Gas Barrier Performance

The core advantage of EW-3201 lies in its ethylene content, ranging from 30.0 to 34.0 mol%. For EVOH (Extracorporeal Membrane Oxide), ethylene content is a crucial parameter:

• Lower ethylene content: More hydroxyl groups (-OH) on the polymer chain, stronger hydrogen bond network, and better oxygen barrier performance.
• Higher ethylene content: Better polymer thermal processability (melt index, flexibility), and improved water resistance, but slightly reduced barrier performance.

EW-3201's 30.0-34.0 mol% ethylene content provides a good thermal processing window while ensuring extremely high oxygen barrier performance. This method is appropriate for packing food items needing strict preservation (like meats, sauces, and milk products) and medical tools needing high levels of cleanliness, which extends how long they can be stored.

2.2 Ideal Processing Performance

The melt index (MI) of EW-3201 is 1.5-2.5 g/10 min, which is a relatively moderate range.

• Moderate MI: This indicates that its melt viscosity is moderate and its flowability is good, making it suitable for high-speed, complex co-extrusion or lamination processes without excessive degradation during processing.
• Importance in Co-extrusion: EVOH is typically used in thin layers sandwiched between structural layers such as PE, PP, or PET. The MI value helps EW-3201 match well with typical adhesives and outer layers. This makes for good mixing of multilayer structures and strong sticking between layers.

2.3 High Density and High Transparency

EVOH typically has a high density (1.10-1.20 g/cm³), attributed to its highly ordered molecular structure and strong hydrogen bonds. High density is the structural basis for achieving high gas barrier properties. Meanwhile, a colorimetric index below 20 ensures that films or containers made from EW-3201 possess excellent transparency and gloss, crucial performance for packaging that needs to display contents (such as high-end food and cosmetics).

2.4. Environmental Sensitivity 

It's important to note that the barrier properties of EVOH are sensitive to environmental humidity. Because the hydroxyl groups on the molecular chain are hydrophilic, when environmental humidity (RH) increases, water molecules enter the hydrogen bond network, weakening hydrogen bonding and leading to increased oxygen permeability. 

• Application Solution: EW-3201 is commonly paired with thermoplastics like PE, PP, and PET in real-world uses. This is done through co-extrusion or lamination to create a multilayer structure. The EVOH layer is placed between polyolefin layers that have good moisture resistance. This effectively protects the EVOH layer from moisture, allowing it to maintain excellent barrier performance even in high-humidity environments.

3. Main Applications

• Food Packaging: Used in the production of oxygen barrier films, cling film, aseptic packaging, tubing, and bag-in-bag systems, significantly extending the shelf life of dairy products, jams, meat, seafood, coffee, and tea.
• Medical Supplies: Used for aseptic packaging of infusion bags and medical devices, preventing product oxidation and microbial contamination.
• Industry and Agriculture: Used as an oxygen barrier layer for underfloor heating pipes to prevent pipe corrosion; or for solvent-resistant containers for solvents and chemicals.
• Cosmetic Packaging: Used in the production of multi-layer cosmetic tubing and containers, effectively preventing the oxidation or volatilization of fragrances, vitamins, and other active ingredients.

As the packaging industry needs thinner, more efficient, and greener materials, good ethylene vinyl alcohol (EVOH) products such as EW-3201 (EVASIN EV-4405F) will keep being very important and will push forward barrier packaging tech improvements around the world. Choosing EW-3201 means choosing a high-performance, highly reliable, and sustainable packaging future.

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