To evaluate the role of nano-sized CaCO3 on creep behavior of PE, a series of PE/CaCO3 nanocomposites were fabricated. To evaluate the dispersion of nanoparticles in PE matrix, scanning electron microscopy (SEM) was employed. To elucidate the creep behavior such as creep rate of pure PE and PE/CaCO3 nanocomposites, thermo mechanical analyzer (TMA60) was used. The creep test was done at constant load of about 20 MPa at different temperature i.e. 30, 60 and 90ºC. The results illustrates that the time dependency of creep strain of PE and its nanocomposites can be divided into three stages. Firstly, rapid elongation would be observed at the beginning of creep test. For all materials initial strain is time independent. The interesting result achieved in the current study is, the initial strain of PE decreases as nano-size CaCO3 added to it. This is because elastic or even plastic deformation of PE would be decreased at the presence of CaCO3. The second stage can be named primary creep step. In fact, in the primary creep stage, the creep rate (dε/dt) decreases rapidly with time because of the slippage and reorientation of polymer chains under persistent load. After a certain period, the creep rate reaches a steady-state value and the secondary creep stage starts. At this stage viscous flow activates and in which a dynamic equilibrium of polymer structure evolution and external load is reached.

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