PA6 Surface Finish improvement

[Pud]

Today we had to use an alternative to toughened PA66 as there appears to be a shortage of the stuff.

We used a toughened PA6. The finish was awful - dull/patchy etc. (Yes, it was dry, melt temperature as measured was in middle of range, blah blah, etc.)

In came my sales manager and suggested adding 2% masterbatch with a PE carrier. Never heard of this before but gave it a go - lo and behold a dramatic improvement in SF!

Any facts or theories why this should be?

H

http://www.tynevalleyplastics.co.uk

 

[Demon3]

Hi Pud,

A friend of mine has seen similar effects. He sells a product called Celspan though Phoenix Plastics in the US. They achieve dramatically better surface finish through the use of a proprietary flow aid.

Poor surface finish is due to roughness which in turn is due to particles at the surface. Change the flow and the particles are no longer at the surface but under it so gloss improves. Also adding a dispersant helps as it lowers the particle size and thereby increases gloss.

I suspect your PE masterbatch is improving flow and may be pumped full of e.g. stearic acid, a well-known dispersant. That's commonly added to masterbatches as it's so cheap.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[Pud]

Cheers Chris - understand that (sort of).

H

http://www.tynevalleyplastics.co.uk