In order to find the relationships between processibility and properties of the polypropylene/ethylene vinyl alcohol copolymer (PP/EVOH) blends, their rheological behavior, in both shear and extensional flows, was studied and related with mechanical, morphological, and barrier properties of the materials. The nonlinear viscoelastic behavior in shear was also analyzed. The data showed that the rheological parameters (viscosity, loss modulus, storage modulus, extensional viscosity, and Trouton ratio) improved with the addition of low quantities of sodium ionomer copolymer used as compatibilizer. At the same time, the overall properties of the PP/EVOH blends improved as a result of the compatibilizer addition. The morphological analysis showed that the changes in the material properties were related with a more uniform distribution of EVOH particles in the PP matrix. The rheological data obtained allowed us to choose the optimal range for EVOH and ionomer contents, especially in terms of combining good processing characteristics with the good final properties.
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Financial support for this work was provided by the Secretaría Xeral de Investigación e Desenrolo, Xunta de Galicia, through grant XUGA-PGIDT02TM17201PR and the Portuguese government through FCT—Foundation for Science and Technology, through grant BD/12833/2003.
Abad MJ, Ares A, Barral L, Cano J, Diez FJ, García-Garabal S, López J, Ramírez C (2004) J Appl Polym Sci 94(4):1763CrossRefGoogle Scholar