Monitoring polyolefin modification along the axis of a twin screw extruder. I. Effect of peroxide concentration



The evolution of the structure of polyolefins with different ethene/propene ratios in the absence or in presence of peroxide was monitored along a twin screw extruder. Small samples were quickly collected from the melt at specific barrel locations and characterized by rheological measurements. The rheological properties of the polyolefins are hardly affected when processing is carried out in the absence of peroxide. In the presence of peroxide both branching/crosslinking and degradation occur along the extruder, until the peroxide is fully converted. The degree of branching/crosslinking and/or degradation depends on the ethene/propene ratio, on the original molecular weight of the polymer and on the amount of peroxide added. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 58–68, 2001