Plastics and Environmental Stress Cracking from Non‑Ionic Surfactants
By Hygiene Technologies
Plastics can fail even when they look strong and undamaged. One common cause is Environmental Stress Cracking (ESC). This type of failure often happens when plastic parts are under load and exposed to everyday chemicals.
One of the most common triggers is non‑ionic surfactants. These surfactants are widely used in cleaning products, detergents, food processing, cosmetics, and hygiene formulations.
Although they seem harmless, non‑ionic surfactants can slowly weaken many plastics. Over time, this can lead to cracks, leaks, or sudden breakage.
Understanding which plastics are vulnerable helps prevent costly failures and product recalls.
Quick Summary: Plastics at Risk
Some plastics are more likely to crack when exposed to non‑ionic surfactants.
High‑risk plastics include:
Polycarbonate (PC)
ABS
Acrylic (PMMA)
PPO blends (such as Noryl®)
Polyetherimide (Ultem®)
Moderate‑risk plastics include:
Polyethylene (HDPE and LDPE)
Polypropylene (PP)
PVC and CPVC
These failures often happen slowly and without warning.
What Is Environmental Stress Cracking?
Environmental Stress Cracking occurs when stress and chemical exposure act together. The plastic may not fail under stress alone. It may also resist the chemical by itself. But when both are present, cracking can begin.
ESC usually starts as tiny cracks that grow over time. Once the crack becomes large enough, the part can fail suddenly.
Why Non‑Ionic Surfactants Cause Stress Cracking
Non‑ionic surfactants behave differently from other chemicals. They can move easily into many plastics, especially when the plastic is already under stress.
They cause damage by:
Entering the plastic’s internal structure
Softening the material like a plasticizer
Feeding liquid into growing cracks
This lowers the force needed for cracks to form and spread.
Technical Breakdown: Plastics Most Susceptible to ESC
Amorphous Thermoplastics (High Risk)
Amorphous plastics have a random molecular structure. This makes it easier for surfactants to penetrate the material.
Polycarbonate (PC)
Polycarbonate is strong and impact‑resistant, but it is highly sensitive to chemical stress cracking. Non‑ionic surfactants can cause cracking even at low stress levels.
ABS (Acrylonitrile‑Butadiene‑Styrene)
ABS is widely used in housings and containers. It has poor resistance to surfactant‑induced ESC, especially in molded parts with residual stress.
PMMA (Acrylic)
Acrylic is prone to crazing and crack formation. Exposure to liquids containing non‑ionic surfactants can cause rapid visible damage.
Modified PPO and Polyetherimide
Materials such as Noryl® and Ultem® offer good thermal properties but can fail in brittle fashion when exposed to environmental stress agents.
Polyolefins (Moderate Risk)
Polyolefins are semi‑crystalline and generally more resistant to chemical attack. However, they are still vulnerable under the right conditions.
Polyethylene (HDPE and LDPE)
Polyethylene is well known for environmental stress cracking. Non‑ionic surfactants can promote slow crack growth, especially under constant load or pressure.
Polypropylene (PP)
Polypropylene shows better resistance than polyethylene but can still fail when exposed to surfactants and mechanical stress over time.
Risk increases with:
Thin wall sections
High internal stress
Long‑term chemical exposure
Other Affected Plastics
PVC and CPVC
These materials can crack when stressed and exposed to secondary chemicals. Non‑ionic surfactants can contribute to this process.
SAN and Other Styrenics
Styrenic plastics behave similarly to ABS and show reduced resistance to surfactant exposure under stress.
Summary Table: ESC Risk from Non‑Ionic Surfactants
Plastic Material- Relative Risk
Polycarbonate (PC) - High
ABS - High
PMMA (Acrylic) - High
PPO / Noryl® - High
PEI / Ultem® - High
Polyethylene (PE) - Moderate–High
Polypropylene (PP) - Moderate
PVC / CPVC - Moderate
Key Takeaways for Design and Material Selection
Non‑ionic surfactants are common but powerful ESC agents
Amorphous plastics are most at risk
Polyolefins are not immune, especially over time
Real‑world chemical testing is essential
Choosing the right plastic early, and testing it with the actual surfactants used, can prevent cracking, downtime, and warranty claims.