Abstract: Two types of polypropylene (PP)/diatomate composites, PP/281 and PP/700, were prepared via melt blending, their impact strength (σⅣ) was evaluated by impact tests, and their fractography obtained from impact testing was observed by scanning electron microscopy. The profile curve of the fractography was extracted by an Image Pro-Plus image processing software, and their fractal dimension (DL) was calculated by a structure function method. The relationship between DL and σⅣ was investigated intensively. The results indicated that the fracture of PP and its composites with diatomate exhibit an evident fractal feature, and DL was in the range of 1.6474～1.7361, which could be used to characterize the fractography of PP/Diatomate composites quantitatively. PP/281 composites had a maximum DL of 1.7361 at a filling fraction (φf) of 10 vol %, whereas PP/700 composites showed a maximum DL of 1.7143 at the φf of 5 vol %. The relationship between DL and σⅣ had a positive correlation and was exponential.

Key words: diatomate, polypropylene, composite, fractography, fractal dimension