Neodymium oxide‐assisted melt free‐radical grafting of maleic anhydride on isotactic‐polypropylene by reactive extrusion

Abstract

Abstract Rare earth oxide, neodymium oxide (Nd 2 O 3 ), ‐assisted melt free‐radical grafting of maleic anhydride (MAH) on isotactic‐polypropylene (i‐PP) was carried out by reactive extrusion. The experimental results reveal that the addition of Nd 2 O 3 into reactive system leads to an enhancement of the grafting degree of MAH, along with an elevated degradation of i‐PP matrix. When Nd 2 O 3 content is 4.5 mmol %, the increment of the grafting degree of MAH (maximally) is up to about 30% compared with that of the related system without adding Nd 2 O 3 , while the severest degradation of i‐PP matrix simultaneously occurs. On the basis of the reaction mechanism of PP ‐g‐ MAH proposed before, the sequence of β‐scission and grafting reaction is discussed in detail. It is found that, for the reactive system studied, most tertiary macroradicals first undergo β‐scission, and then, grafting reaction with MAH takes place at the new radical chain ends. The imported Nd 2 O 3 has no effect on the aforementioned reaction mechanism, whereas it enhances the initiating efficiency of the initiator, dicumyl peroxide (DCP). We tentatively explain the experimental results by means of synergistic effect between DCP and Nd 2 O 3 . It is calculated that the synergistic effect is maximal when the molar ratio of DCP to Nd 2 O 3 is approximately 1:6. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 134–142, 2006