Effect of Organo-Modified Montmorillonite (O-MMT) on Mechanical and Barrier Properties of LLDPE/LDPE Blend Films

In this study, the effect of organo-modified Montmorillonite (Cloisite 15A) on mechanical and gas barrier properties of nanocomposite films of LLDPE/LDPE blends was investigated. Two different compatibilizing agents, PE-g-MA and PP-g-MA, were used toobtainthe better dispersion of the nanoclay in the blends.The blend samples containing various amounts of the clay were prepared via melt compounding and then blown to films. Mechanical properties of the films were studied in machine and transverse directions. A constant volumeand variable pressure method was used to determine the gas permeability of the films. The XRD results showed that the samples containing PP-g-MA as compatibilizer would make a finer dispersion of the organoclay in these samples. A broad peak was observed in XRD patterns of the sample with 1 phr organoclay which indicated partial exfoliation state. In other nanocomposites, the clay diffraction peak shifted to lower angles, indicating the intercalated structures in these nanocomposite films. The permeability results showed that addition of organoclay even at low level hada significant effect on barrier properties of the nanocomposite films. Oxygen permeability decreased 38% by adding only 4 phr of the nanoclay into the blend. Addition of the clay also led toan increase in tensile modulus in both directions without decreasing the elongation at break of the films. Nielson’s model and the Halpin–Tsai equation were used to calculate the number of stacks of the clay in the nanocomposites using permeability and modulus results, respectively. These models predicted the stack number between 2 and 3 for the nanocomposites which confirmed a fine dispersion of closite 15A in the films

کلیدواژه ها:

low density polyethylene ، linear low density polyethylene ، gas barrier properties ، Cloisite 15A ، nanocomposite ، mechanical properties