POLYMER ADDITIVES

Polymer processing additives are used to reduce melt fracture, increase the processing window, and eliminate die-lip build-up and gels in polyolefins.  Some additives may interfere with the performance of the polymer processing additive by four main mechanisms – adsorption, abrasion, site competition, and chemical reaction. Strong bases such as hindered amine light stabilizers can cause the polymer processing additive to lose effectiveness, due to both site competition and chemical reaction. In the presence of HAS, chemical reactivity is possible with typical polymer processing additives composed of reactive fluoropolymers, which are most frequently used in these applications. While such an interaction occurs, it has been demonstrated that the HAS interaction does not change its stabilizing ability, but only affects the performance of the processing additive. Nonreactive polymer processing additives have been found. It allows for broader selection of other additives, processing at higher temperatures, and reduces the required amount of polymer processing additive necessary to eliminate melt fracture and lower extrusion pressure.