Grafting of itaconic acid on low density polyethylene in the molten state has been investigated. Static and dynamic mixers assembled on the Brabender plastograph have been used as a blender of reagents and as a chemical reactor. Shear rates were 50 and 100 s(-1). Dicumyl peroxide; 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane; 2,2-di-(tert-butylperoxy)-5,5,6-trimethylbicyclo-[2,2,1]-heptane; 2,2-di(3-methyl-1-butyne-3-peroxy)-5,5,6-trimethylbicyclo[2,2,1]heptane; 2,5-dimethyl-2-hydroxy-5-tert-butylperoxy-3-hexyne were used as peroxide initiators of grafting.