Process for making graft propylene polymers

A continuous melt process for making a graft copropylene copolymer comprising contacting a propylene polymer selected from the group consisting of homopolymers of propylene and an .alpha.-olefin, wherein said .alpha.-olefin comonomer contains 2 to 12 carbon atoms and is present in a concentration of between about 0.5% and about 40%, said percentages being by weight, based on the total weight of the copolymer, and propylene copolymers with at least one polymerizable, ethylenically unsaturated carboxylic acid or acid derivative in the presence of a coagent having the structural formula (CH.sub.2 .dbd.CR.sup.1 --CR.sup.2 --R.sup.3).sub.x R, where R.sup.1, R.sup.2 and R.sup.3 are the same or different and are hydrogen, hydrocarbyl, halogen or a heterocyclic radical;

• x is an integer of 2 to 4;
• and R is a radical containing at least one atom of oxygen, sulfur, nitrogen, phosphorus or silicon having a valence equal to the value of x, said coagent present in a concentration in the range of between about 0.01% and about 30% by weight, based on the weight of the propylene polymer, and a free radical generating compound, said process conducted at a temperature above both the melting point of said propylene polymer and the decomposition temperature of said free radical generating compound.