Free-radical grafting of itaconic acid onto LDPE by reactive extrusion: I Effect of initator solubility

摘要

The eft.ect of the peroxide initiator nature on the grafting of itaconic acid (IA)onto low-density polyethylene (LOPE) was investigated in the course of the reactive extrusion. It was shown that at other equal conditions. the solubility of the peroxide initiator in the molten polymer is most imponant in the IA grafting onto LOPE. The thennill stability of peroxide initiators is also imponant. At the synthesis conditions of preparing the grafted products by the reactive extrusion. peroxides, which decompose at temperatures far below the IA melting point (also in the feed zone of the extruder), can be used to initiate grafting reactions. It is very probable that radicals fonned trom peroxide decomposition interact first with LOPE macromolecules, while the fonned macroradicals initiate IA grafting reactions. Peroxides, which are easily dissolved in LOPE, are recommended for initiating the efficient grafting reactions. The closer the thennodynamic affinity between the peroxide and the monomer, the less the efficiency of grafting. Higher transponation velocities of the reactive blend in the extruder-reactor intensify LOPE crosslinking, thus lowering the IA grafting efficiency.