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In this study, the rheological characteristics of metallocene linear low density polyethylene (mLLDPE) were analyzed. Cyclohexane was used to prepare the dilute solutions of mLLDPE. The concentrations used in this study ranged from 1000 to 4500 ppm with 1000 ppm increments. The test temperatures ranged between 293 and 323 K at 10 K increments. The shear rate range was from 0.8 and 600 s À1 . Rheological measurements were performed on a rotational rheometer model AR-G2 with parallel plate geometry. The solution rheology was affected by shear rate, polymer concentration, and testing temperature. Different models were used to describe the rheological behavior of the mLLDPE dilute solutions. A model that accounted for concentration was successful in describing the rheological behavior as compared to models that were developed for polymer melt, which do not take the polymer concentration into account.

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High density polyethylene (HDPE) with micro calcium carbonate (CaCO 3 ) masterbatch was pelletized by using a twin screw extruder and different ASTM specimens were molded by an injection molding machine. The morphology of the composites was characterized by scanning electron microscopy (SEM) and Image Analysis software. The dispersion and interfacial interaction between CaCO 3 and the polymer matrix were also investigated by SEM. The thermal properties of HDPE and its composites were investigated by differential scanning calorimetry (DSC). The crystallization process of the composites samples was found to be slightly different than that of the neat HDPE. Otherwise, the presence of CaCO 3 did not have a considerable effect on the melting behavior of the composites. Thermogravimetric analysis (TGA) revealed that the composites had better thermal stability than the neat HDPE resin as indicated by a higher temperature of 50% weight loss (T 50% ) for the composites as compared to that of the neat resin. The viscoelastic properties of the composites and HDPE were also investigated via torsional and rotational techniques. The presence of CaCO 3 increased the shear modulus at low frequency of the composites at 80 C over that of the neat resin. However, at higher frequencies, the difference between the neat resin and the composites' shear modulus was less than that at low frequencies. The complex viscosity of the composite increased upon the addition of CaCO 3 . However, the shear sensitivities of the neat resin and the microcomposite were similar.

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Polypropylene/clay nanocomposites were prepared by melt blending technique. A PP homopolymer was melt blended with commercial nanoclay masterbatch at different concentration (5, 10 and 15 wt% of nanoclay) using Laboratory Mixing Extruder (LME). The morphology of the nanocomposites was characterized using Scanning Electron Microscope (SEM). The viscoelastic and thermomechanical properties were analyzed via Dynamic Mechanical Analysis (DMA). The morphological analysis showed that the nanoclay was well distributed in the PP matrix. The DMA analysis showed an increase in storage modulus of nanocomposites which indicates an enhancement of stiffness and thermal stability of the prepared nanocomposite samples. In addition, a nanoindentation test was performed to determine the dynamic nanomechanical properties of two nanocomposites samples (NS-5 and NS-15). Load sweep test results showed that NS-15 has a slightly higher storage and loss modulus than that of NS-5. Both the samples also showed a decreasing modulus as a function of depth, indicating the presence of a stiffer surface layer in the samples. Frequency sweep tests were also performed on each sample, and display a moderate viscoelasticity with modulus values that increased slightly as a function of frequency. Loadcontrolled ramping force scratch test was also carried out and the results showed that NS-15 had a greater elastic recovery than sample NS-5 as well as a greater overall scratch resistance.