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Researchers Struggle to Find Viable Replacement for Stress Cracking Reagent


By GNA Editor | 7th August 2023

Global Laboratories Face Dilemma as Key Surfactant Igepal Faces Phase-Out

In the world of geomembrane testing, researchers are facing a formidable challenge as they search for a suitable replacement for the stress cracking reagent Igepal. Despite numerous trials conducted across laboratories worldwide, no viable candidate has emerged to fill the void left by the gradual phasing out of Igepal.

The surfactant Igepal has long been a staple in stress crack resistance testing of HDPE geomembranes. However, with its availability increasingly restricted, the geomembrane testing community finds itself in a quandary regarding future testing protocols.

Labs across the globe have united in their quest for an alternative surfactant that can match Igepal’s performance in stress cracking tests. Four potential substitutes have been identified and put to the test, selected based on efficacy and availability:

  • Solvay: IGEPAL CO-630 (10% by volume) at 50°C
  • Solvay: Rhodasurf LA-9 (10% by volume) at 50°C
  • DOW: Tergitol 15-S-15 (5% by mass) at 70°C
  • BASF: Dehyton PL (10% by volume) at 70°C

Unfortunately, all known substitute surfactants tested so far exhibit unique characteristics that can affect stress cracking in HDPE geomembranes differently (see table of results below). One crucial setback is the absence of a REACH-compliant surfactant with the same SP-NCTL signature as Igepal CO-630, which is commonly used with polyethylene geomembranes in the industry.

Through extensive round-robin testing, researchers have concluded that no REACH directive compliant surfactant possesses an exact equivalent efficacy to Igepal CO-630. This realization adds further complexity to the search for a suitable replacement.

Among the tested substitutes, Tergitol at 70°C has posed specific challenges during experimentation. At room temperature, Tergitol solidifies, necessitating dilution in hot water before introducing it to the stress cracking bath. This practical limitation raises doubts about its viability as a replacement surfactant from a handling perspective.

Similarly, Dehyton did not yield shortened time horizons for the stress crack test when used at an elevated temperature of 70°C. Researchers also caution that testing at higher temperatures introduces its own set of challenges, including difficulties in temperature control and maintenance, as well as potential issues with accelerated corrosion over time.

The industry remains hopeful that a suitable alternative will be found in due course, but until then, researchers and labs continue their tireless efforts to identify a viable replacement that meets the demanding standards of stress crack testing for HDPE geomembranes.

As the search for the ideal substitute continues, the geomembrane testing community remains steadfast in their commitment to advancing the field and ensuring the quality and safety of geomembrane applications worldwide.

References and Further Reading

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