Polymers tend to lose elastic modulus over time, particularly under dynamic loading. A geocell system must maintain stiffness and elastic properties without permanent deformation or loss of geometry, which could result in losing confinement or even worse crack and fail.
The Dynamical Mechanical Analysis (DMA) examines the net elastic modulus of polymers. The analysis extracts the polymer stiffness in the elastic mode – the ability to apply loads on the system without permanent deformation.
A stable net elastic modulus also ensures elastic behavior at elevated temperatures.
This method is well supported by ASTM and ISO standards e and commonly used in the automotive, electronic, military industries. The following table summarize the PRS-Neoloy® Geocells Elastic (Stiffness) Modulus Properties.
|NET ELASTIC MODULUS – DMA|
|PROPERTIES||MINIMUM REQUIREMENTS||UNITS||TEST METHOD|
|Net Elastic Modulus – sample temp:|
The DMA also enables the effective service temperature range (elastic behavior) by a mathematical determination as follows. The Neoloy-based PRS-Neoloy (Tough Cells) effective service range is -60°C to +60°C.
Higher DMA values mean higher elastic modulus; this is lower permanent (plastic) deformation and better performance over the long-term.
Unlike HDPE, Neoloy-based PRS-Neoloy (Tough Cell) shows predictable stiffness at typical as well as elevated temperatures for accurate risk analysis and long-term design. HDPE geocell manufacturers do not reference this property or test.