EFFECTS OF FILM THICKNESS AND INHIBITOR CONCENTRATION ON THE SORPTION AND THERMAL POLYMERIZATION OF ACRYLIC-ACID IN LOW-DENSITY POLYETHYLENE

We investigated the effects of hydroquinone monomethyl ether concentration and film thickness upon the thermal polymerization of acrylic acid on low-density polyethylene. The thermal polymerization of acrylic acid on low-density polyethylene depended on the concentration of hydroquinone monomethyl ether inhibitor. It was a free-radical reaction with initiation on the film surface and then proceeding to the bulk matrix. The process was not controlled by monomer diffusion for the range of film thickness of 90-200 mum. It became a diffusion-controlled process at higher film thicknesses (> 200 mum). A film layer of up to 100 mum was proposed as the limiting thickness for a diffusion-free process.