Polyethylene Wax (PE Wax)

Polyethylene wax (PE wax) is a synthetic wax made of low-molecular-weight polyethylene chains. It is solid at room temperature and turns into a very low-viscosity liquid when heated. In industry it is not a main ingredient but an additive that, used correctly, markedly improves both the process and the end product.

How it is made

There are three main routes, and they largely determine the properties of the product:

• Direct polymerization: Produced by the controlled polymerization of ethylene. Gives a narrow molecular weight distribution and high purity.
• Thermal cracking: Obtained by breaking down high-molecular-weight polyethylene with heat. Economical, with a broader molecular distribution.
• Oxidation: Controlled oxidation of non-oxidized wax adds carboxyl groups to the chain, giving it polarity and emulsifiability.

Measured parameters

Five values determine how a PE wax behaves:

• Drop point (ASTM D3954 / D127): The temperature at which the wax starts to flow. It sets the application temperature and the heat resistance of the end product. Typical range 100–140 °C.
• Viscosity at 140 °C (ASTM D3236): Melt flow. Lower viscosity means better wetting and dispersion. Typical range 10–500 mPa·s.
• Penetration (ASTM D1321): A measure of hardness. A lower value means a harder wax.
• Acid value (ASTM D1386): Meaningful only for oxidized types; it indicates polarity and compatibility with polar surfaces. Typical range 14–30 mg KOH/g.
• Density (ASTM D1505): 0.92–0.94 g/cm³ for LDPE-type waxes, 0.95–0.98 g/cm³ for HDPE-type waxes.

Where it is used

As an external lubricant in PVC pipe and profile extrusion, a dispersion aid in black and color masterbatch production, a viscosity and open time modifier in hot-melt adhesives, a rub resistance additive in printing inks and paints, a processing aid in rubber processing, a fiber additive in textiles, a hardness enhancer in candle production and a flow modifier in asphalt and road marking materials.