The peroxide degradation of polypropylene was studied in supercritical carbon dioxide (scCO2) in the presence of a N-hydroxyphthalimide (NHPI). Six levels of NHPI concentration and 6 levels of peroxide concentration were selected and each permutation was tested both with and without scCO2. It was observed that the NHPI would increase degradation at lower peroxide concentrations (<0.1 wt. %), but would suppress degradation at higher peroxide concentrations (>0.2 wt. %). Furthermore, it was discovered that at an NHPI concentration of 3.3 wt. %, the stereo regularity slightly decreased with increasing peroxide concentrations.
Keywords: Polypropylene, degradation, β-scission, epimerization, peroxide, n-hydroxyphtalimide, supercritical carbon dioxide.