PREDICTION OF FRACTURE MECHANISM FOR POLYMER NANOCOMPOSITES

Abstract

Nanocomposites of thermoplastic polyurethane (ester based) filled with CB and reactive OMMT (cloisite 3013) were synthesized using melt mixing method. Effect of CB (3 wt.%) and reactive OMMT (1-3 wt.%) on dynamic mechanical, tensile, thermal and fracture properties of TPU were studied. EWF method was used to quantify thin film (plane stress) fracture toughness in mode I of TPU nanocomposites. FTIR was performed to determine the change in degree of phase separation, on addition of OMMT, between hard and soft segments of TPU. Completely exfoliated structures were reported at I and 2 % OMMT but intercalated structures were observed at 3% OMMT, may be due to agglomeration. Increment of 16.8 % and 74 % in We and l3wp respectively were observed with 2% OMMT. CB has mostly shown negative impact on tensile and fracture properties of TPU. Ductile instability for crack growth was not observed in these composites. However, due to presence of both fillers as particulates, crazing was observed in these composites.