Preparation And Barrier Properties Of HDPE Polymer Blend With Laminar Structures

The barrier solutions presently available on the market all have their drawbacks, e.g. cost or perceived environmental bad-will. This situation has stimulated the industry to provide new, more efficient barrier solutions. The use of laminar morphology of polymer blends to obtain good barrier (i.e., low permeability) to hydrocarbons has been of considerable interest recently. Such a structure will represent a long, tortuous path for the gas or solvent penetrating the blend.Laminar morphology has been demonstrated in single screw extruders and blowing machines. Both processes have shown that viscosity and elasticity ratios, and interfacial tension between the matrix and dispersed phase, are important parameters in the development of the morphology of blends . To our knowledge, few studies have been done regarding the development of laminar morphology in the twin screw extruders. The main objective of this work was to evaluate the formation of laminar morphology of polymer blends in a co-rotating twin screw extruder and prepare the barrier containers.Firstly, the morphology of samples of different HDPE/PA6 and HDPE/PET blends obtained by three kinds of HDPE and rotational speeds was observed using SEM. Appropriate selection of materials in combination with SEM photos and material parameters results in developing laminar morphology in co-rotating twin screw extruder of HDPE/PA6 and HDPE/PET blends. Temperature profile, shear rate and screw rate, as the processing parameters, and compatibilizer levels were considered in this study. The study provides the basis for choosing processing conditions and polymer blend components to obtain expected laminar morphology of polymer blends. Furthermore, the barrier and mechanical properties of the blends were evaluates and optimized. In order to obtain products with optimum balance between the permeability and the mechanical properties, a statistical analysis was carried out.Secondly, it is showed that HDPE/PA6 blend is better than HDPE/PET blends by the statistical evaluation of permeability results and the analysis of blow- molding process.Finally, temperature profile and shear rate was used to optimize processing conditions in developing laminar morphology in blow molding HDPE/PA6 blends. The result is shown that it is good to form laminar morphology of dispersed phase PA6 in proper temperature profile and lower shear rate. It is also shown that blow molded bottles with laminar blend of HDPE and PA6 reduce greatly in permeability, compared to the bottles made from HDPE.