What does HALS mean in the Geocell Industry?

In the geocell industry, HALS stands for Hindered Amine Light Stabilizers.

It’s a very important chemical additive used to protect geocells from breaking down due to sunlight exposure.

1. What is HALS?

HALS is a type of stabilizer that is mixed into the plastic material (usually polypropylene or polyethylene) when the geocells are being made.

2. What is its purpose? (Why do geocells need it?)

Geocells are used in outdoor construction projects like:

Road and railway foundations
Slope protection
Embankment reinforcement

They are constantly exposed to sunlight, specifically the ultraviolet (UV) rays within it.

Without HALS: UV rays have a lot of energy. They break the plastic’s molecular structure, causing the geocell to:
- Become brittle and crack
- Lose strength and load-bearing capacity
- Change color and degrade on the surface
  This process is called “UV degradation.” A degraded geocell can fail, risking the entire project.
With HALS: HALS acts like a powerful, built-in “sunscreen” for the geocell. It works continuously to:
- Absorb and neutralize the harmful energy from UV rays.
- Prevent the chemical reactions that cause the plastic to break down.

3. How does HALS work? (Simple Explanation)

HALS works as a “radical scavenger.”

UV light attacks the plastic and creates damaging particles called “free radicals.”
These radicals quickly spread, breaking more molecular chains and causing the material to weaken.
HALS effectively traps and neutralizes these free radicals, stopping the destructive chain reaction.
Importantly, HALS can re-generate itself after it works. This allows it to provide long-term protection for many years.

Key Points to Remember:

Main Job: Fight UV degradation to significantly extend the geocell’s service life.
Why it’s Important: It is a key indicator of the geocell’s durability and quality. Geocells with sufficient, high-quality HALS can have a design life of 50 years or more.
Industry Standards: Product standards often require geocells to pass “xenon-arc weathering tests,” which simulate long-term sun exposure. Using HALS is the primary way for manufacturers to meet these requirements.

So, when you see a geocell product described as “UV resistant” or “with high-quality anti-aging agents,” it usually means it contains effective HALS (Hindered Amine Light Stabilizers).