IXPE and PE foam are both polyethylene, and they are often quoted against each other on price alone. The difference is the cross-link: PE foam is expanded polyethylene, IXPE is polyethylene that has been cross-linked by an electron beam before expansion. That one step changes how the foam behaves under heat, under load, and at thin gauges — and it is what you are paying for.
What a cross-link does
Polyethylene is a thermoplastic: heat it and it softens, then flows. Cross-linking ties the polymer chains into a three-dimensional network before the foam is expanded, so the material no longer melts and flows the way plain PE does. In practice that shows up in four places:
- The foam keeps its thickness when it gets hot, instead of collapsing.
- It springs back after compression instead of taking a permanent set.
- The cell walls stay intact, so the closed-cell structure survives handling and converting.
- It can be made in very thin single layers without the cells collapsing.
There are two ways to do it. XPE uses a chemical cross-linking agent; IXPE uses an electron beam. Both are cross-linked; IXPE has no cross-linking agent residue, which is why it can go thinner and has a finer, more uniform cell structure.
The practical comparison
| Property | Plain PE foam | IXPE (cross-linked) |
|---|---|---|
| Structure | Thermoplastic, not cross-linked | Cross-linked network; closed cell |
| Behaviour when heated | Softens and can collapse under load | Holds its shape; no melting under normal service |
| Recovery after compression | Low; takes a set | Compression set ≤2 % to ≤11 %, measured to GB/T 6669 |
| Thinnest single layer | Limited by cell collapse | 0.1 mm |
| Density range | Varies by supplier | 26.8–300 kg/m³, 3x–40x expansion |
| Water absorption | Closed cell, but walls are weaker | ≤0.2 % to ≤0.4 %, GB/T 1034, 23 °C / 22 h |
| Thermal conductivity | Comparable order of magnitude | 0.040–0.095 W/m·K, depending on density |
| Price | Lower | Higher — one more process step |
| Recycling | Can be re-melted | Cannot be re-melted; ground and used as filler |
Two of these rows decide most projects. The first is recovery: if the part is compressed and released, or compressed and held for years, plain PE will creep and stay flat while IXPE returns. The second is thickness: below about 3 mm, a non-cross-linked foam is difficult to make well, while IXPE is routinely produced down to 0.1 mm in one layer.
Where plain PE foam is the better buy
Plain PE foam is not a bad material — it is the right material for a narrower set of jobs:
- Void fill and dunnage, where the foam only has to take up space.
- Single-trip protective packaging for light products.
- Blocks and planks cut to size, where thickness is large and precision is not critical.
- Applications where the part is never compressed for long and never sees heat.
If the part is any of those, paying for cross-linking buys nothing you can use. The honest answer to "do I need IXPE?" is sometimes no.
Where IXPE pays for itself
- Thin parts. Gaskets, tape carriers, keyboard pads, battery spacers — anything under 3 mm.
- Repeated compression. Sealing, cushioning that is loaded and unloaded thousands of times.
- Heat in service. Parts near a motor, a battery or a light source, where a thermoplastic foam would soften.
- Clean converting. Die-cutting and CNC routing leave a cleaner edge on a cross-linked foam, and the cell structure does not collapse at the cut.
- Consistency across orders. Density and thickness repeat from batch to batch, which matters more than the price difference on a part that has to fit.
What IXPE does not solve
Cross-linking does not make foam strong. It is still a cushioning material, not a structural one. It does not make it UV-stable — that is a formulation change you have to specify. And it does not make it recyclable in a mechanical stream: cross-linked PE cannot be re-melted. If recycled content is a requirement from your customer, that has to be settled before the material is chosen.
How to specify it
Two numbers do most of the work: expansion ratio and thickness. Ratio sets density and hardness — 3x is about 300 kg/m³ and firm, 40x is about 26.8 kg/m³ and soft. Thickness sets the cushioning travel. Send both, plus the application and the environment, and the grade follows. If you only send a material name, you will get a quote you cannot compare with anyone else's.
FAQ
Is IXPE the same as XPE?
Both are cross-linked polyethylene foam. XPE is chemically cross-linked; IXPE is irradiation cross-linked. IXPE can be made thinner (from 0.1 mm) and has a finer cell structure.
Can I replace IXPE with plain PE foam to save cost?
Only if the part is thick, lightly loaded and never hot. Below 3 mm, or under repeated compression, plain PE will not hold the specification.
Does IXPE absorb water?
It is closed-cell. Water absorption is ≤0.2 % at 3x–15x and up to ≤0.4 % at 30x–40x, measured to GB/T 1034 over 22 hours.
Is IXPE recyclable?
It cannot be re-melted. It can be ground and used as filler; otherwise plan for energy recovery.
Related reading
IXPE foam: specifications · XPE foam · XPE foam: limits · All foam materials
Not sure which one your part needs? Send the drawing and the operating conditions and we will say which grade fits — including when the cheaper one does.