The effects of three kinds of compatibilizers on the structure and mechanical properties of the blends of nylon 6/thermoplastic polyamide elastomer have been studied. The torque curves of melt blending showed that effective compatibilizers reacted with nylon 6 matrix with increasing blending time and they generated a uniform crystalline texture composed of fine spherullites and fine rubber particles. As a result, the impact strength of the alloys with effective compatibilizers was increased to 10.5 times of the nylon 6 matrix in the temparature range from -45 to 45°C. This is about double the impact strength of alloys without any compatibilizer. The effects of the addition of compatibilizers can be attributed to the generation of the fine uniform elastomer distribution rather than to the enhancement in the interfacial strength between the matrix and elastomer.

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For the analysis of the fiber orientation mechanism, it is necessary to continuously observe the rotation behavior of fibers at a series of positions from the gate to the end of the cavity, and to more quantitatively observe the behavior of fibers in the fountain flow near the flow front using highly magnified images.
In this study, we propose a method of visual observation utilizing a fiber tracing system and new Back-Lighting Mold, by which we can observe the entire region from the gate to the end of the cavity. Using this method, we have elucidated how the structure of seven orientation layers was formed during the filling process of polystyrene with low fiber concentration of 0.1-0.2wt%. The results obtained through the visual analysis are summarized below.
(1) The above method is effective for the analysis of the fiber orientation mechanism.
(2) In the vicinity of gate, the fiber orientation angle is subjected to the influence of divergent flow at the center of the cavity thickness, and also subjected to the influence of shear flow near the cavity wall.
(3) Immediately after the fibers flow out of the gate, the fibers in the core layer rotate from parallel to perpendicular to the flow direction by the influence of divergent flow. In the subsequent parallel flow region where the fibers are not influenced by divergent flow, the fibers flow perpendicular to the flow direction.
(4) The fibers in the intermediate layer are greatly influenced by shear flow near the cavity wall as compared to that of divergent flow even near the gate. They flow parallel to the flow direction during the whole cavity filling process.
(5) The fiber orientation in the skin layer depends on the position where the fiber rotates near the flow front during the fountain flow process. The rotating fibers near the surface of the flow front form Skin layer I, and those inside the flow front form Skin layer II.

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