The polymerization and grafting of the monomers p-acryloyloxybenzoic acid and p-methacryloyloxybenzoic acid were studied. Poly(acryloyloxybenzoic acid) was obtained by gamma-radiation-induced solution polymerization and bulk melt polymerization initiated by dicumyl peroxide. Poly(methacryloyloxybenzoic acid) could be obtained only by bulk melt polymerization. The graft copolymerization of the monomers onto isotactic polypropylene was carried out in bulk. The maximum grafting was reached in shorter times at higher temperatures, and it also increased with the concentration of the monomers in the reaction medium. The thermal and crystallization behavior of the graft copolymers was studied with differential scanning calorimetry and wide-angle X-ray diffraction. The graft copolymerization of p-acryloyloxybenzoic acid did not have any influence on the formation of both alpha-forms (monoclinic) of polypropylene, whereas p-methacryloyloxybenzoic acid led to the alpha(2) form. The beta-crystalline modification (hexagonal) formed in poly(acryloyloxybenzoic acid)-g-polypropylene products at 185 degrees C and at higher grafting temperatures and also in the second run of differential scanning calorimetry studies after fast cooling. The beta form was not observed in graft copolymers of poly(methacryloyloxybenzoic acid). (C) 2007 Wiley Periodicals, Inc.