Investigation on Thermo-Mechanical Crosslinking Phenomena of Commercial High Density Polyethylene during Extrusion using Capillary Rheometer and Dynamic Mechanical Analysis (DMA)

Two different actions affecting the molecular weight of the polyethylene may take place during extrusion: crosslinking which converts the thermoplastic polymer into a threedimensionalstructure and degradation by chain scission, which splits the polymer chains and thus, decrease the averagemolecular weight. These actions may occur as undesirable phenomena during entire polymer life cycle of production, processing, service life and possible recycling. In this work the crosslinking of stabilized and unstabilized high density polyethylene have been studied in an industrial twin screwextruder. Our study method can be used as a practical way to investigate on the validity of different additives such asantioxidant, whereas it is expected these chemical react with primary radical generated in melt during extrusion. meanwhile, the correlation between crosslinking and rheological properties has been discussed.