The Relationship Between Rheology and Morphology of the Dynamically Vulcanized Thermoplastic Elastomer Based on EPDM/PP
Fatemeh Goharpey, Ali Asghar Katbab, Hossein Nazockdast
Dept of Polymer Eng. Amir Kabir University of Technology
IRAN
Keywords: Thermoplastic Elastomer , Rheology , viscoelastic properties
Attempts were made to study the relationship between rheological properties and morphology of the dynamically vulcanized TPE based on EPDM/PP containing 20, 40 and 60 % of EPDM. The samples were prepared in a laboratory internal mixer at rotor speed 60 rpm. Morphological studies were performed on the samples which were cryogenically fractured and then etched with xylene using SEM. The rheological behavior and viscoelastic properties of the samples were studied by Reometric Mechanical Spectrometer (RMS) at temperature of 220 ºC . The TPV’s samples a significant up-turn in dynamic viscosity and storage modulus was observed at low shear rate range with it’s highest extent for the sample containing 60% of rubber. These results were attributed to the network structure resulting from agglomerates formed between cured rubber particles. The results of relaxation time distribution showed an additional peak for the samples containing 60% of EPDM which could be due to the interfacial interaction between the two phases. These results were in a good agreement with the morphological feature of the samples observed by the SEM. The viscoelastic properties of the samples were compared with the prediction of a model proposed by Palierne for dilute particulate composite. However the agreement was only found for high shear rates. A modified model with considering the maximum packing of rubber particles was proposed and good agreement was found.