This thesis was studied on the basic properties, rheological properties, crystallization behavior, and blowing behavior of modified polypropylene (m-PP) and m-PP/nano-filler composites.
m-PP was prepared by melt grafting and the m-PP/silicate composites in the range of 1 - 7 wt%, using a mini-compounder at 190 oC. The chemical structure of the m-PP was confirmed by the existence of a -C=C-H stretch peak at 3100 cm-1 in the FT-IR spectrum. Based on thermal and rheological properties, FS was the best in branching efficiency of PP. Compared PP, m-PPs indicated an increase of complex viscosity in the low frequency and shear thinning tendency, and G''-G" plot represented an increase in elasticity and the heterogeneousness in melt state. Rheological properties of m-PP/silicate composites were observed with silicate content. When 5 wt% silicate was added in the m-PP, there were distinct changes in the shear thinning tendency and the slope of G’-G” plots. The non-isothermal crystallization behavior of the m-PP was analyzed using by Ozawa equation. The extending exponents were 3.6 for PP, 2.5 for m-PP-F03 and 1.5 for the composite. These values indicate that the crystal structure of PP changes from sphere to disk and rod like structure. These behaviors can be interpreted by the speculation that the silicate in PP matrix may act as seeds for crystallization and may change the crystallization process.
m-PP/nano-filler composite were prepared by adding the silicate and MWCNT of 5 wt%, using twin screw extruder. m-PP/nano-filler composite showed high complex viscosity in the low frequency and G''-G" plot represents an increase in elasticity. The silicate is more dispersion than MWCNT in m-PP/nano-filler composites. The non-isothermal crystallization behavior of the m-PP/nano-filler composites were analyzed using by Ozawa equation. The modified Avrami exponents were 3-4 for m-PP-D/nano-filler composite, 2-2.5 for m-PP-F/nano-filler composites. In case of homo PP, the blowing behavior enhanced dramatically for m-PP-D/nano-filler and m-PP-F/nano-filler composite, but there was no change in blowing behavior for m-PP-H/nano-filler composite. Among nano-fillers the silicate composite was the best in enhancing blowing behavior.