synthesis and characterization of epdm elastomers

a series of ethylene-propylene-2-ethylidenebicyclo [2.2.1] hept.5-ene terpolymers (epdm) have been prepared using a vocl3/al2et3cl3 catalyst under various al/v ratios and diene concentrations via solution polymerization and characterized by ftir, mooney viscosity (ml1+4,125oc), and thermal gravimetery analyzing. the polymerization yield was seen to increase with augmentation of the al/v ratio and  diene concentration and pass through a maximum of about 200 gr polymer/g v. on the other hand, mooney viscosity decreases with an increase in the two latter parameters. increasing solvent to monomer ratio increased polymerization yield while it decreased mooney viscosity. accordingly, an optimum amount of solvent to monomer ratio (4:1 in mass) was found. one advantage of these polymer systems is that all the measured tg property remained constant around 232-240 k in the range of incorporated ethylene and diene concentration. it has been observed that when al/v ratio decreases and diene concentration increases, there is an increment in ethylene incorporation (40-60%), and the results have been compared with the characteristics of two commercial epdms (herlen 563, vistalon 7500).