A new technique for preparing polyethylene/polystyrene blends with gradient structure

In this study, polyethylene (PE)/polystyrene (PS) polymeric gradient material with spatially gradient structure was prepared continuously by a new technique through coextrusion–gradient distribution–two‐dimensional mixing with conventional polymeric material processing facilities. The processing line from coextrusion, gradient distribution to two‐dimensional mixing was fulfilled by two extruders, gradient distribution unit, and two‐dimensional mixing units, respectively. The gradient distribution unit and two‐dimensional mixing units were designed separately in our group. The gradient variation of composition along the sample thickness direction was studied by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). DSC results indicated that a gradient variation of the content of PE was formed along the sample thickness direction. SEM results showed the direct evolution of morphology of each specimen along the sample thickness direction. The experimental results demonstrated that the processing method with coextrusion–gradient distribution–two‐dimensional mixing can be served as a new way to produce polymer blends with spatially gradient structure and worth to be further investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007