The main technological properties of thermoplastic elastomers (TPE) include melt flow rate (MFR) and density.
The melt flow rate (MFR) is the amount of molten TPE extruded through a capillary under specified load conditions per unit of time. For TPEs, the standard test conditions are typically 190 °C and a 5 kg load.
According to their melt flow rate, TPE grades are conventionally divided into two groups:
- Extrusion and vacuum forming grades: MFR = 1–10 g/10 min (190 °C, 5 kg)
- Injection moulding grades: MFR = 20–200 g/10 min (190 °C, 5 kg)
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The density of thermoplastic elastomers is determined primarily by the amount of filler contained in the formulation. In addition to reducing material cost, fillers perform several important functions — they help reduce product shrinkage, warping, and melt swell after extrusion. Commonly used mineral fillers include talc, chalk (calcium carbonate), and silica.
Typical standard densities for TPE materials are as follows:
| Filler Content | Density (g/ml) | Description |
| Unfilled | 0.90 | Pure base polymer |
| 10–15% filled | 1.00–1.02 | Lightly filled material |
| 20–25% filled | 1.08–1.10 | Moderately filled material |
| 30–35% filled | 1.16–1.22 | Heavily filled material |
| 40–45% filled | 1.30 | Highly filled material |