Abstract
A commercial linear low density polyethylene (LLDPE) was modified by adding a small amount dicumyl peroxide (DCP) during extrusion at moderate processing temperature (200°C). The effects of peroxide modification were to change the molecular weight and rheological properties, as evident by increase in high molecular portion, shear sensitivity and melt viscosity at low frequency region. These effects were confirmed by gel permeation chromatography (GPC) and Rheometric dynamic spectrometer (RDS). One outstanding feature of peroxide modification was the remarkable delay in the onset of melt fracture upon extrusion. The dilution of DCP in polypropylene (PP) powder was more effective for improvement of these properties than by direct loading of DCP. The observed remarkable delay in melt fracture is believed to be due to increase in high molecular portion by producing long chain branch and crosslinking. That is, DCP modification results in delay in the onset of melt fracture through increase in high molecular portion which can resist high elongational stress when leaving the die.
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Kim, Y., Yang, K. Effect of Peroxide Modification on Melt Fracture of Linear Low Density Polyethylene during Extrusion. Polym J 31, 579–584 (1999). https://doi.org/10.1295/polymj.31.579
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DOI: https://doi.org/10.1295/polymj.31.579