No.5（2002）4.Impact Strength of Injection Molded Polypropylene by Falling Weight Method

Kenichi SHIMIZU, Satoshi ABE and Makoto YAMAMOTO

Injection molded polypropylene was investigated in the correlation between impact strength and molding conditions using the falling weight method. The sample pieces, measuring 100×100×3mm, were molded in the combined conditions with the cylinder temperature 200℃ or 260℃, the mold temperature 30℃ or 60℃ and the injection velocity 16.6cm³/s or 49.8cm³/s. The impact strength was better in the case of the molding condition at the higher cylinder temperature and the lower mold temperature, in which larger spherulites were raised. On the contrary, the injection velocities had little effect on the impact strength. The time dependent deterioration of impact strength was observed in some conditions. In this sample, multiplied crystallinity was not admitted from the X-ray diffraction pattern, only the growth of the absorbance ratio at 998cm-1 to at 974cm-1 was recognized in the infrared spectrum.

Keywords
Polypropylene, Injection Molding, Impact Strength, Falling Weight Method, Spherulite

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