No abstract

Maleic anhydride grafting onto polypropylene was conducted in a twinscrew extruder according to an experimental design in which the maleic anhydride and peroxide concentrations were varied. The modified polypropylene was characterized by FTIR spectroscopy, melt-flow index measurements, size-exclusion chromatography, differential scanning calorimetry, and nuclear magnetic resonance. The results showed that only the independent variable peroxide concentration influenced the amount of reacted maleic anhydride, whereas the two variables studied influenced the molecular weight of the grafted polypropylene.

ABSTRACT:Grafting reactions were performed in a Haake torque rheometer, according to a central composite experimental design, where the maleic anhydride and peroxide concentrations, rotor speed, and reaction time were varied. The 27 formulations were analyzed by Fourier transformed infrared spectroscopy and melt-flow index measurements (MFI). An increase in peroxide concentration caused an increase in the percentage of reacted maleic anhydride and in MFI. The effect of initial maleic anhydride concentration presented different types of behavior, depending on the peroxide level.

No abstract

Grafting of maleic anhydride onto polypropylene was performed in a Haake torque rheometer, according to a central composite experimental design, in which four factors were varied: the maleic anhydride and peroxide concentrations, rotor speed, and reaction time. The current article investigates the effect of rotor speed and reaction time on the level of reacted maleic anhydride, obtained by infrared spectroscopy, and on the extent of degradation, by means of melt-flow index (MFI) measurements. The behavior of the variables studied depends on the levels of maleic anhydride and peroxide concentrations. The increase in rotor speed results in an increase in the percentage of reacted maleic anhydride and a reduction in MFI when the initial maleic anhydride concentration is high, and in a reduction in the percentage of reacted maleic anhydride and increase in MFI when the initial maleic anhydride concentration is low (for the central levels of peroxide concentration and reaction time). The effect of the variable reaction time depends on the remaining parameters.