2. Experimental
2.1. Materials
The two polymers used to prepare the TPNR were natural rubber and polypropylene, and both were obtained from Enterprise Nation ale des plastiques et Caoutchoucs (ENPC, Algeria). NR is an SMR20 grade with a density of 0.93 g/cm3 and a Mooney viscosity ML(1 þ 4)100 of 60. PP is a CLYRELL RC1314 injection molding grade with a density of 0.90 g/cm3 and a melt flow index MFI (230 C/2.16 Kg) of 9 g/10 min. The peroxide used to initiate the grafting reaction was
dicumyl peroxide (DCP) which was supplied in powder form by Bayer ltd. It has a density of 1 g/cm3 with a decomposition temperature of 130 C. Maleic anhydride was supplied from Fluka Co. The curatives used for the dynamic vulcanization
namely sulphur, TMTM (tetra methyl thiuram monosulfide), ZnO (zinc oxide) and stearic acid were standard materials used for rubber formulation and were used as supplied.