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 twi n screw extruder. Small samples were quickly collected from the melt at spe cific barrel locations and characterized by theological measurements. The r heological properties of the polyolefins are hardly affected when processin g is carried out in the absence of peroxide. In the presence of peroxide bo th branching/crosslinking and degradation occur along the extruder, until t he 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. (C) 2001 John W iley & Sons, Inc.