MELT STRENGTH AND ELASTIC BEHAVIOR OF LLDPE LDPE BLENDS/

Differences in processability between linear low denisty polyethylene (LLDPE) and low density polyethylene (LDPE) as well as for their blend s subjected to extensional flow were assessed in terms of melt strengt h and elastic parameters from shear flow such as storage modulus (G'), and first normal stress difference (N-11 - N-22). The results reveale d similar synergistic effects for these parameters in the LDPE rich bl ends. A DSC rest carried out on these LLDPE/LDPE blends when fast cool ed disclosed the existence of two phases in the molten blends for the same composition range where the melt strength synergism was observed. The results are discussed in terms of the influence of the different molecular structures of the blend polymers and their miscibility on th e measured melt strength. A mechanism is suggested to explain the obse rved synergistic phenomenon.