Functionalisation of ethylene–propylene copolymer by melt grafting of maleic anhydride using a high shear internal mixer

Abstract

This study focused on synthesising a peroxide-initiated maleic anhydride-g-ethylene–propylene copolymer via melt grafting using a Haake internal mixer at high shear rate. The effect of maleic anhydride and dicumyl peroxide percentage on the grafting efficiency of maleic anhydride onto ethylene–propylene copolymer chains was carried out through a two-level factorial experimental design using Design Expert 6.0.5 software. The maleic anhydride and dicumyl peroxide content were varied, in the range of 1–5 and 0·1–0·3 phr, respectively. The grafting parameters were fixed at a temperature of 180°C and rotor speed of 60 rev min⁻¹ for 5 minutes. The grafting efficiency was determined by Fourier transform infrared spectroscopy analysis based on cumulative absorbance of anhydrides’ characteristic peaks and supported by differential scanning calorimetry and field emission scanning electron microscopy analyses. The grafting was highly influenced by maleic anhydride and dicumyl peroxide content. The optimum functionalisation was achieved at 5 phr maleic anhydride and 0·3 phr peroxide addition.

Keywords:

• Ethylene–propylene copolymer (EPM)
• Melt functionalisation
• Maleic anhydride
• Grafting parameters
• Rubber blends incompatibility