This work demonstrates that acrylic acid (AA), glycidyl acrylate (GA) and several other acrylic monomers can be photopolymerized and photografted onto high-density polyethylene (HDPE) by self-initiation. The self-initiation mechanism of these acrylic monomers is possibly by an excitation of the monomer to a triplet state (T-3) with enough energy to abstract hydrogen from the polymer substrate and initiate the grafting.