How to Select Raw Material for HDPE Geomembrane? TR-131 & TR-400
TR-131 and TR-400 are internationally recognized grade designations for HDPE geomembrane raw materials, adopted by various chemical manufacturers for ease of identification. Our company uses high-quality polyethylene resins (from Qatar Energy, Sinopec, etc.) as raw materials for geomembrane production, complying with GB/T17643-2025 and GRI-GM13.
This article shares the similarities and differences between two raw materials and the experience of producing geomembrane (referencing the descriptions provided on the official website of Qatar Energy)
https://www.qatarenergy.qa/en/MarketingAndTrading/Marketing/Pages/OurProducts.aspx
Q1: Similarities between TR-131 and TR-400
- Density | ASTM D4976: 0.938 g/cm³
classified as Medium Density Polyethylene (MDPE)
- Brittleness Temperature | ASTM D746: <-75°
Q2: Key differences between TR-131 and TR-400
- ESCR | ASTM D1693:
| TR-131 | ≥1000 h |
|---|---|
| TR-400 | ≥1500 h |
TR400 has more outstanding ESCR, making it more suitable for long-term use or major anti-seepage projects.
- Melt Index | ASTM D1238:
| TR-131 | 0.2 g/10min |
|---|---|
| TR-400 | 0.11 g/10min |
The lower the melt index (MI), the higher the molecular weight of the resin, the poorer the melt flowability, and the greater the processing difficulty; however, the mechanical properties and durability of the final product are also better.
Q3: Why choose MDPE resin to produce HDPE geomembrane?
The processing of geomembrane is a complex process. The application of the final product can be influenced by various factors such as transportation, construction and environment. Therefore, the materials used in HDPE geomembrane need to be adjusted according to actual conditions.
In ASTM D4976 standard, polyethylene resins are strictly classified according to density as:
- HDPE: ≥ 0.941 g/cm³
- MDPE: 0.926 – 0.940 g/cm³ （TR-131 & TR-400）
However, according to the current standards of GRI-GM13 and GB/T 17643, HDPE geomembrane needs to include 2-3% carbon black (with a density of approximately 1.8 – 2.1 g/cm³) to resist the effects of UV light and aging. And the final geomembranes can reach a density >0.941 g/cm³, which belong to HDPE geomembrane.
If HDPE resin is chosen as the primary raw material, its more regular molecular structure (low ESCR) will bring it more stress cracking. It is unsuitable for long-term projects such as landfills or reservoirs.
Conversely, MDPE resin can achieve performance comparable to HDPE with its excellent ESCR and copolymer modification capabilities. These features give the geomembrane high strength, high rigidity and most importantly, the outstanding durability.
Q4: How to choose between TR-131 and TR-400?
In the production, Both TR-131 and TR-400 can be used as raw materials for HDPE geomembranes. According to Qatar Energy's TDS, the two materials have different application focuses:
TR-131 is softer and easier to process, used for:
- the middle layer of composite geomembranes (with geotextile)
- general municipal environmental projects
- flat and simple application scenarios
- better cost control
TR-400 has high modulus and is difficult to process, used for:
- smooth and textured geomembranes
- major municipal project and hazardous waste treatment projects
- complex application scenarios
- better long-term safety and stability
In conclusion, how to select materials must consider many factors. Manufacturers should ensure product quality can meet project design requirements and reduce unnecessary cost waste , for healthy development of enterprise and the market.
Reference：
Polymers_HDPE_MDPE_QTR131_TDS.pdf
Polymers_HDPE_MDPE_QTR400_TDS.pdf
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