Abstract: A study has made on the thermal, x-ray diffraction, and dynamic mechanical characterit-tics of polypropylene(pp)(containing 22% ethylene)filled with wollastonite. Differentlevels of β-form crystallinity were produced in the pp by mixing wollastonite. All the sa-mples filled with wollastonite contain both β and a-forms and four melting transitions wereobserved instead of two for the unfilled pp. The crystals were found to be changed from β-form to a-form on heating. The relative proportions of β-form present in the specimens was measured from the x-raydiffraction diagram by an empirical ratio K.The K value increases with increasing the con-tent of wollastonite fillers. Wollastonite in the composite is as a reinforecement and nucleator for β-form crystalsof pp and it is bound into crystalline phases of pp.

Key words: polypropylene composite, wollastonite, dynamic mechanical properties, crystal form