This study covers the preparation and characterization of perlite-filled po
lypropylene (PP). The compositions of 15, 30, and 50 % by weight perlite-PP
composites were prepared by melt-mixing. The PP used in this study was eit
her applied in the virgin form or gamma -irradiated in air at the doses of
10, 25, 50, and 100 kGy to determine the effect of oxidative degradation in
composite properties. Furthermore, the active sites containing oxygen prod
uced by gamma -irradiation in PP may provide a possible enhancement by the
interfacial interaction between perlite and PP. An initial sharp drop in to
rque readings during the melt-mixing of perlite-PP composite preparation in
dicated an extensive chain scission and degradation by gamma -irradiation.
The thermal properties of the composites were characterized by DSC. The ult
imate tensile strength and elongation and also impact strength decreased in
all composites with gamma -irradiation. Yet, these changes appeared not to
be faster than was the change in unfilled PP upon irradiation. Scanning el
ectron microscopy revealed an interfacial adhesion between perlite and irra
diated PP while virgin PP did not show any evidence of adhesion. (C) 2001 J
ohn Wiley & Sons, Inc.