Kinetics for grafting two reactive monomers (dibutyl maleate (DBM) and maleic anhydride (MAH)) on polyethylene (PE) was investigated for the modified PE (PE-g-MAH and PE-g-DBM) using solid phase grafting process. This process avoided solvent waste produced in solution process and high operation temperature in melt process. In the presence of the radical initiator, coupling reactions, between the PE and product, and macromolecular radicals, routinely form gels and/or increase molecular weight, resulting in a worse rheological behavior for the grafting products. By adding small amount of interface agents, using combined initiators and optimizing reactor design, graft copolymers with controlled grafting degrees and good rheological properties were prepared. The grafting degrees of copolymers were determined by chemical analysis. FTIR, DSC, and pure water contact angle characterized the chemical structure, the thermal property, and the hydrophilic property of the grafting copolymers, respectively. The peel strength of the graft copolymer as powder coating on the stainless steel surface was measured as high as 12-24 kgf/cm. Mechanical strength and toughness of PE/kaolin clay, PVC/CPE, and PVC/CPE/CaCO3 alloys with small amount of the graft copolymer (similar to 5 wt %) added were improved significantly. (c) 2006 Wiley Periodicals, Inc.