PolyAl mechanical properties: test data, standards and how to read a datasheet
ISO 527 tensile, ISO 178 flexural, Charpy impact, Vicat, density and ash — what each number means and which to weight.
Specifying PolyAl for a structural application requires reading datasheets confidently. This article walks through every number you will see on a PolyAl pellet datasheet, what test it comes from, and what range to expect.
Density (ISO 1183)
950–1050 kg/m³ for PolyAl pellets. Higher than virgin HDPE (940–960) because of the aluminium content. Density correlates linearly with ash percentage.
Melt Flow Index — MFI (ISO 1133, 190 °C / 2.16 kg)
2–4 g/10 min. This is a high-viscosity grade similar to HDPE blow-moulding compounds. For thin-wall injection (< 1.5 mm), prefer the upper end of the range.
Ash content (ISO 3451-1)
Up to 13 % — this is the metallic aluminium fraction, plus a tiny amount of inorganic residue. The aluminium acts as a stiffening filler and reflects UV.
Moisture (ISO 15512)
< 0.15 % as supplied. PolyAl is hydrophobic; only worry about moisture if the bag has been opened in a humid environment for weeks.
Tensile (ISO 527)
- Tensile strength at yield: 10–15 MPa
- Elongation at break: 30–80 %
Lower than virgin HDPE pipe grades (22–28 MPa) because the aluminium platelets create stress concentrations. Adequate for non-load-bearing structural applications.
Flexural (ISO 178)
- Flexural modulus: 220–520 MPa
- Flexural strength: 12–18 MPa
Wide range because PolyAl batches vary in aluminium content. For pallets and decking, request a flex modulus > 400 MPa.
Vicat softening point (ISO 306, B/50)
90–100 °C. Acceptable for outdoor service in any climate.
Charpy impact (ISO 179, notched, 23 °C)
5–8 kJ/m². Lower than virgin HDPE (15–25 kJ/m²) but adequate for thick-walled industrial parts. Avoid sharp corners in design — fillet to 2 mm minimum radius.
Cleaning chemical resistance (UNE 56875:2021)
Passes both general and intensive cleaning regimes. Important for logistics pallets and food-handling crates (non-food-contact).
Torsion (UNE-EN 14195:2015)
Ratio 0.040 ≤ 0.1. Pallet quality indicator under European logistics standards.
What to ask the supplier for
A per-batch certificate of analysis (CoA) covering the above plus:
- Carbon black content (if applicable)
- HALS / UV-absorber package
- Heavy metals (RoHS / REACH compliance statement)
- Origin of feedstock (carton recycler name and country)
The per-batch CoA is the single most important document for ESG procurement and CSRD reporting.