Hg. Gang et al., FRICTIONAL-PROPERTIES OF POLYOLEFINS TREATED WITH FLUOROELASTOMER PROCESSING AIDS, Journal of applied polymer science, 55(10), 1995, pp. 1465-1476
A friction measurement system was designed that made possible the meas
urement of the friction coefficient between a polymer melt and a metal
die wall. The shear stresses developed in the capillary rheometer and
the friction coefficient measured in the friction measurement system
were compared in an attempt to understand the mechanism of fluoroelast
omer processing aids (FPA) in the extrusions of polypropylene (PP) and
linear low-density polyethylene (LLDPE). The apparent viscosity drops
of LLDPE treated with FPA were larger than those of PP treated with F
PA. The friction coefficient drops of LLDPE treated with FPA were also
larger than those of PP treated with FPA. High viscosity FPA showed a
moderate friction coefficient drop in the actual extrusion of PP even
though it showed only a poor effect in the capillary rheometer. The f
rictional forces were calculated from the friction coefficient measure
ment made during extrusions of FPA-treated and untreated samples. (C)
1995 John Wiley & Sons, Inc.