Rheological, Mechanical, and Oxygen Barrier Properties of Polymer/layered Silicate Nanocomposite Films based upon PE and EVA

In this work, various low density polyethylene/poly (ethylene-co-vinyl acetate) (LDPE/EVA) nanocomposites containing 1-7 wt% of organoclay were prepared based on one-step and two-step procedures, through melt blending in a twin screw extruder. The resultant nanocomposites were then processed via film blowing method. From the morphological point of view, X-ray diffraction (XRD) and optical microscopy studies revealed that although a prevalent intercalated morphology was evident in the absence of the EVA, a remarkable increase of organoclay interlayer spacing was observed for the EVA containing systems. This Polymer/nanoparticles interaction enhancement was corroborated by performing rheological experiments on the prepared samples. The advantages of the addition of the EVA to the LDPE/organoclay nanocomposites were also confirmed in terms of oxygen barrier properties. In other words, the oxygen transmission rate (OTR) values of LDPE/EVA/organoclay systems were significantly lower than that of the LDPE/organoclay sample. In addition, the LDPE/EVA/organoclay films had higher mechanical properties than their counterparts lacking the EVA, which could be addressed to the improvement of the organoclay reinforcement efficiency in the presence of EVA. Furthermore, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) experiments were performed to follow the effects of the EVA and/or organoclay contents on the thermal properties of the LDPE matrix. Finally, the films produced from the two-step procedure compound showed enhanced properties in terms of oxygen barrier and mechanical behavior as compared to those of the films produced from the one-step procedure one

کلیدواژه ها:

LDPE ، EVA ، nanocomposite ، film blowing ، Oxygen permeability ، Mechanical properties