Preparation of modified polybutene-1 by oxidation and limonene radical grafting using an Nd2O3-assisted radical initiator system and its characterization

Free radical graft polymerization has been used as a modification method to incorporate functional groups into polyolefins using a melt-mixing process. In this work, modification of polybutene-1 (PB) was performed by limonene radical graft polymerization using the Nd2O3/dicumyl peroxide (DCP) radical initiator system with various mixing ratios in air. The effects of the modification on the crystallization and tensile behavior were studied in detail. The modified PB samples had ketone and limonene groups. The contents of both the ketone and the limonene groups were highest in the modified PB prepared using Nd2O3/DCP (2/0.2 wt%/PB), and a conjugated diene group was found to be produced by a side-reaction. Excess Nd2O3 lowered the limonene graft content in the modified PB. The rate of crystal phase transition (II -> I) decreased with an increase of limonene content. The presence of a small amount of the ketone group increased the rate, and the modified PB having a small ketone content exhibited more ductility due to its higher crystal phase transition rate. It was found that there was an optimum mixing ratio of the Nd2O3/DCP initiator system for the modification. The ketone and the limonene groups affected the rate of the crystal phase transition and the tensile properties of the modified PB. (C) 2010 Society of Chemical Industry