Oxygen permeability and the mechanical and thermal properties of (low‐density polyethylene)/poly (ethylene‐co‐vinyl acetate)/organoclay blown film nanocomposites

Abstract

Various (low‐density polyethylene)/poly(ethylene‐co‐vinyl acetate) (LDPE/EVA) nanocomposites containing organoclay were prepared by one‐ and two‐step procedures through melt blending. The resultant nanocomposites were then processed via the film blowing method. From the morphological point of view, X‐ray diffraction and optical microscopy studies revealed that although a prevalent intercalated morphology was evident in the absence of EVA, a remarkable increase of organoclay interlayer spacing occurred in the EVA‐containing systems. The advantages of the addition of EVA to the LDPE/organoclay nanocomposites were confirmed in terms of oxygen barrier properties. In other words, the oxygen transmission rates of the LDPE/EVA/organoclay systems were significantly lower than that of the LDPE/organoclay sample. The LDPE/EVA/organoclay films had better mechanical properties than their counterparts lacking the EVA, a result which could be attributed to the improvement of the organoclay reinforcement efficiency in the presence of EVA. Differential scanning calorimetry and thermogravimetric analysis experiments were performed to follow the effects of the EVA and/or organoclay on the thermal properties of LDPE. Finally, the films produced from the two‐step‐procedure compound showed enhanced oxygen barrier properties and mechanical behavior as compared to the properties of the films produced via the one‐step procedure. J. VINYL ADDIT. TECHNOL., 19:132–139, 2013. © 2013 Society of Plastics Engineers

Tuning the nano/micro‐structure and properties of melt‐processed ternary composites of polypropylene/ethylene vinyl acetate blend and nanoclay: The influence of kinetic and thermodynamic parameters

“…This is demonstrated by the presence of OMMT particles at the interphase and in the dispersed EVA ], stabilizing the morphology of the blend. Another interesting aspect to note is that the TEM images of melt-pressed nanocomposites revealed a morphological instability for most samples except for the [P80C5O4] 3 (E20) 9 nanocomposite which shows better morphology. The EVA in the [P80C5O4] 3 (E20) 9 composite was mixed for a longer time suggesting it experienced longer shearing resulting in breakage of EVA phase into small droplets.…”

“…Another interesting aspect to note is that the TEM images of melt-pressed nanocomposites revealed a morphological instability for most samples except for the [P80C5O4] 3 (E20) 9 nanocomposite which shows better morphology. The EVA in the [P80C5O4] 3 (E20) 9 composite was mixed for a longer time suggesting it experienced longer shearing resulting in breakage of EVA phase into small droplets. Once the EVA phase is broken down into small droplets, the MA groups of PP-g-MA can interact with the vinyl acetate groups of EVA and prevent coalescence of the droplets.…”

“…Once the EVA phase is broken down into small droplets, the MA groups of PP-g-MA can interact with the vinyl acetate groups of EVA and prevent coalescence of the droplets. In melt-pressing [P80C5O4] 3 (E20) 9 composite the EVA droplets do not coalesce due to the stabilization by OMMT platelets and other thermodynamic factors. In the other ternary nanocomposites, the mixing duration of EVA was relatively short and MA groups of PP-g-MA did not have sufficient time to interact with vinyl acetate groups of EVA and prevent coalescence of the droplets hence the samples show instability during melt pressing.…”

“…It can be assumed that the extent of intercalation was not very large, due to the hydrophobic nature of PE. However, Hosseinkhanli et al 9 revealed that, in film-blown composites, EVA improves the compatibility between PE and organoclay (Nanomer V R I31PS). This was indicated by the reduction in the intensity of the Xray diffraction (XRD) peak of the nanoclay and the decrease in the nanoclay aggregate size when EVA was added to the LDPE/ nanoclay composite.…”

“…The morphologies of LDPE/nanoclay and LLDPE/nanoclay composites have been reported previously. [8][9][10] In these studies, PE/nanoclay composites were prepared by either film blowing or injection molding.…”