A coagent masterbatch comprising a semi-crystalline polyolefin carrier resin and an alkenyl-functional coagent. A peroxide curable formulation comprising the coagent masterbatch and a polyolefin compound. A method of making the masterbatch and formulation; a peroxide-cured polyolefin product prepared therefrom; a manufactured article comprising or made from the masterbatch, formulation, or product; and a method of using the manufactured article.