Maleation of Poly(4-methyl-1-pentene) Using Supercritical Carbon Dioxide

The heterogeneous free-radical grafting of maleic anhydride (MAH) onto poly(4-methyl-1-pentene) (PMP) was studied using supercritical carbon dioxide as the solvent/swellant. The anhydride content in the product can be controlled by using variations in time and temperature to achieve maleations as high as 7 mol % at 125 °C after a 5 h reaction period. A comparison between benzoyl peroxide (BPO) and dicumyl peroxide (DCP) initiators indicates that DCP is the more effective initiator. The effect of reactant concentrations on the degree of grafting is also examined, yielding an optimum MAH:DCP molar ratio of 3:2. Competitive cross-linking of the substrate is the major drawback to this means of polymer modification.