The morphology and properties of HDPE/Nylon blend were studied. According to the processing condition, compatibilizer and composition ratio of HDPE, Nylon and compatibilizer, the blend shows the various morphology such as sphere, cylinder and laminar shape. The unusual barrier effects obtained at small concentrations of the barrier material (Nylon) are obtained by the controlled morphology of the dispersed phase and optimum formulation of the ingredients. In the case of laminar morphology, Nylon is distributed as large thin sheets parallel to the flow axis. These Nylon platelets act as barriers to the permeant molecule by providing a long tortuous path.
In this study, laminar morphology of HDPE/Nylon blend was obtained using a single screw extruder with tubular die.
Addition of compatibilizer in the HDPE/Nylon blend is essential for producing laminar morphology. Graft copolymers such as HDPE-g-MAH, HDPE-g-(MAH-co-St) were prepared by the reactive extrusion in the single screw extruder and twin screw extruder. HDPE-g-(MAH-co-St) showed high melt index as well as high graft yield of MAH.
As compared to the permeability of the fine, isotropic dispersion of HDPE/Nylon blend, which was 1.2 times than that of HDPE virgin, the permeability of the laminar morphology was reduced 43 times than that of HDPE virgin.
The interfacial tensions of HDPE/Nylon binary blend and HDPE/Nylon/compatibilizer ternary blend were obtained by rheological measurements. The interfacial tension of the ternary blend was reduced to 6.26 dyne/cm, compared to that of the binary blend, 16.31 dyne/cm.
Computer simulation for the permeability of the HDPE/Nylon blend was carried out. Permeability of HDPE/Nylon blend with varying the morphology of HDPE/Nylon blend was calculated by GRM (Generalized Rayleigh Maxwell) relationship. As the Nylon platelet width was increased and thickness was decreased at constant volume fraction of Nylon, the estimated values showed the large reduction of the permeability. The simulated results were compared with the experimental values.