he rheological behaviors of impact polypropylene copolymer (IPC) were studied by means of dynamic rheological tests.The dynamic rheological measurements were conducted on an Advanced Rheometric Expansion System with parallel plate geometry of 25 mm diameter under air and N2

respectively.Two sorts of tests were performed under conditions as follows:(1) isothermal frequency sweeps from 100 rad#8226;s－1to 0.01 rad#8226;s－1at different temperatures from 190℃ to 230℃ in steps of 20℃;(2) isothermal time sweeps at a frequency of 0.05 rad#8226;s－1and a strain of 5% under different temperatures from 190℃ to 230℃.The development of melt structure for IPC was probed through examining the influence of temperature

atmosphere and additive antioxidant on dynamic rheological functions.Results reveal that the rheological functions vary with the increase of temperature.The second plateau appears in the logarithmic plots of the dynamic storage modulus versus frequency

lgG′-lgω

in the low ω range.Moreover

for the IPC samples exposed to N2 or blending with antioxidant

this second plateau disappears in a certain time period

being a representation of the rheological properties for homogeneous polymers.Furthermore

rheological functions in the low ω range can sensitively reflect the oxidationinduced degradation and crosslinking of IPC.