Extrusion-injection molding preparation method

The ninth and final chapter discusses characterization methods for poly-ethylene-based composites and nanocomposites, explaining the most significant features of the processing, characterization, and properties of PE composites. In the section that discusses processing, different techniques used for preparation of PE composites are explained extrusion, injection molding and compression molding. Another section of this chapter... 

Figure 5 presents the results of tensile tests for the HPC/OSL blends prepared by solvent-casting and extrusion. All of the fabrication methods result in a tremendous increase in modulus up to a lignin content of ca. 15 wt.%. This can be attributed to the Tg elevation of the amorphous HPC/OSL phase leading to increasingly glassy response. Of particular interest is the tensile strength of these materials. As is shown, there is essentially no improvement in this parameter for the solvent cast blends, but a tremendous increase is observed for the injection molded blend. Qualitatively, this behavior is best modeled by the presence of oriented chains, or mesophase superstructure, dispersed in an amorphous matrix comprised of the compatible HPC/OSL component. The presence of this fibrous structure in the injection molded samples is confirmed by SEM analysis of the freeze-fracture surface (Figure 6). This structure is not present in the solvent cast blends, although evidence of globular domains remain in both of these blends appearing somewhat more coalesced in the pyridine cast material.

In this method, the nanofillers are mixed with the polymer matrix in the molten state. This method has great advantages over either in-situ intercalative polymerization or solution intercalation. First, this method is environmentally benign due to the absence of organic solvents. Second, it is compatible with current industrial processes such as extrusion and injection molding. The melt intercalation allows the use of polymers, which are not suitable for in-situ polymerization or the solution intercalation method. A wide range of silicone rubber nanocomposites have been prepared by this method [143,144]. 

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