[mmsh]

Hi everyone,
I'm trying to make one item for my project from linear low-density polyethylene (LLDPE). What I do is load lldpe powder into metal mold and heat it. As a result i get mostly what i want except that item is too slippery and i need it to have more friction on it's surface.
I've tried to mix LLDPE with different materials like rubber powder or marble dust but this materials just find themselves inside of polyethylene. They do not change friction of item's surface or friction of polyethylene itself.

Any ideas how it will be possible to make item from LLDPE less slippery?

[Corribus]

What LLDPE are you using? Most commercial resins have a slip agent (lubricant) added. You could try extracting this from the LDPE before you do your molding, but keep in mind you'll lose all the antioxidants as well, could could lead to some polymer oxidation during heating.

Alternatively, can you just mechanically abrade the surface with grit paper?

[hollytara]

Either sandpaper on final product or modify your mold to make the surface rough.

[Enthalpy]

PE and PP are nearly the worst possible choice for strong friction. ABS would be much better and PVC not bad, in this price category.

The effect of roughness is small  and not intuitive. A rougher surface may very well decrease the friction. It happens with polymer plain bearings against steel shafts, which shall not be too smooth.

Deposit a molten rubbing polymer on the PE surface, hoping they bind firmly? For instance hot glue brings strong friction.
https://en.wikipedia.org/wiki/Hot-melt_adhesive
Melt some in a pan, apply it with a brush. The final dimensions will grow.

Or apply a molten rubbing polymer like hot glue on the mould's wall prior to moulding the PE?

I'm also surprised by "load lldpe powder into metal mold and heat it". Due to voids in the powder, the molten polymer can't fill the mould. Huge viscosity also tends to miss the shape's details. Is this acceptable? Normally, polymers are injected in the (pre-heated) mould with a huge pressure. Industries have pumps designed for that, I guess some special hand pump could do it too.

[Enthalpy]

Take some fine powder, like sand, silica...
Heat it for real separately. The powder must be able to melt the PE surface.
Plunge your PE part in the powder like a escalope in breadcrumbs. For small parts, you can use chopsticks.

Maybe you can deposit the hot powder on the polymer part, but the powder must not cool down meanwhile.

Depending on the powder used, the part becomes abrasive, and the final dimensions grow.

[mmsh]

PE and PP are nearly the worst possible choice for strong friction. ABS would be much better and PVC not bad, in this price category.

Take some fine powder, like sand, silica...
Heat it for real separately. The powder must be able to melt the PE surface.

Interesting ideas! Will try different type of polymer and will try to heat marble dust separately. Thanks!