The polymerization of methyl isopropenyl ketone (MIPK) inside low-density polyethylene beads has been studied with lauroyl peroxide as the initiator. The reaction was carried out by first immersing the polymer beads in a liquid solution of MIPK monomer and initiator for 5 h at 55 degrees C and then draining the excess liquid. The temperature of these monomer-soaked beads was increased to a reaction temperature (85 degrees C) and the monomer was polymerized in the solid resins. The bulk polymerization of MIPK and the sorption characteristics of MIPK and initiator were also investigated through experimentation and model simulation. It has been observed that the monomer uptake in the solid polymer increased considerably in the presence of the lauroyl peroxide initiator in the liquid phase during the sorption stage. The differential scanning calorimetry study also indicated that some changes in the polymer morphology have occurred due to the incorporation of poly-MIPK into the polyethylene resins.