| Functionally gradient materials (FGM) are composites in which the material composition is varied spatially to optimize the property of material for a specific application. The concept originated with Japanese scientists in the 1980s and has been successfully implemented in a new-type ceramic/metal composite to prepare super heat-resistant materials for aerospace applications. In contrast to the ceramic/metal system and other inorganic materials, however, there have been relatively fewer experimental studies of polymeric gradient materials (PGM), especially in preparing PGM by use of traditional polymer material processing facilities. The aim of this study, therefore, is trying to combine the conception of functionally gradient material, and creating a processing method to prepare PGM by use of conventional facilities.In this dissertation, a novel method for preparing PGM is studied. PP/PA6, PP/talc columnar and flat PGM are prepared successfully by using the modified extruding technique. Structure and property of these columnar or flat PGM are investigated through measurements of WAXD, TG, SEM, elemental analysis and mechanical tests. Experimental results indicate that the composition, morphology and property varied gradually in both columnar and flat PGM. In PP/PA6 columnar PGM, the content of PA6 increased gradually while PP decreased along the radius direction. A phenomenon of phase inversion is observed when the percentage of PA6 is higher than that of PP. The morphological feature of respectively sliced specimen from the PGM is similar to the traditional blend in which the difference between any two domains could be neglected. The whole structure of the PGM prepared in this study, however, is very different from the traditional blend because the morphology of each sliced specimen varies gradually along the radius direction of the PGM sample. The Young's modulus increases with the increased PA6 content while the tensile strength and breaking elongation depend strongly on the morphological structure and show diverse variation. In PP/talc columnar PGM, the percentage of talc gradually increased with increasing radius, and a gradually increased stacking density of talc in PP matrix is observed. Tensile tests indicate that Young's modulus increases while breaking elongation decreases with increased talc content. Lower talc content shows good modified effect, which makes tensile strength improved, but higher talc content shows poor effect.Three modes of PP/PA6 (signed with A1, A2, A3) and PP/talc (signed with T1, T2, T3) flat PGM are prepared, respectively. In mode A1, the content of PA6 increases gradually from one side to another side along its thickness direction. In mode A2 and A3, the content of PA6 decreases or increases gradually from central part to the outside of flat PGM, respectively. Phase reversion also observed among all modes of the PP/PA6 flat PGM. In addition, A1 shows obviously different mechanical properties on its two sides due to the difference of composition distribution. For samples T1, T2 and T3, the gradient variation in both structure and physical property are also examined through measurements of WARD, TG, SEM and mechanical and thermal expansion determination. A fine dispersion of talc with a lower stacking density was observed when the filler content is lower than 40%, and a discontinuous PP matrix was found when the content of talc is higher than 60%. For mode T1, the content of talc changes monotonously from 0% to 62% along the thickness direction. As a result of such variations in component and structure, the physical property on both sides of the flat sample exhibits a significant difference. Young's modulus increases from 380 to 930 MPa, while the corresponding elongations decreases from 1300% to 4%, respectively. Besides, the disparity of thermal expansion property on its two sides was observed.All experimental facts show that polymeric gradient materials have been prepared successfully by use of this modified extruding technique.
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