Combining boron nitride with a fluoroelastomer: An enhanced polymer processing additive

The effect of a new processing additive (boron nitride powder in combinatio n with a fluoroelastomer) on the rheology and processability of molten poly mers is studied. The equipment used includes an Instron capillary rheometer equipped with a special annular die (Nokia Maillefer wire coating cross-he ad) and a parallel-plate rheometer. Metallocene polyethylenes with and with out boron nitride (BN) and fluoroelastomer are tested in extrusion. First, it is demonstrated that BN is a superior processing aid compared to convent ional fluoropolymer ones. Second, it is found that the combination of BN po wders with a small amount of a fluoroelastomer improves even further the pr ocessability of molten polymers (melt fracture performance).