Process aid eliminate melt facture at given shear rate to allow for higher throughput before onset begins again. It is a Fluoro Polymer based processing additive Melt facture 

Melt facture is a surface roughness on films or other extruded shapes resulting from a slip/stick action on molten polymer exiting a die. It is most often seen with tougher resin such as LLDPE & HDPE. Also known as Sharkskin, Orange peel, Wavy zigzag.

Key Characteristics 

Its incompatible with PO also act as lubricant. 
Improve Polymer flow in extrusion. 
Improve productivity 
Reduces back pressure 
No die buildup and die lines 
No gel formation 
Reduces back pressure 
Improves surface finish and gloss 
Quicker color changeover & reduces machine startup time. 
Power consumption effectively reduces.