Abstract: A series of reactive maleic anhydride terminated polyethylene glycol was synthesized and used as a toughening modifier of the unsaturated polyester specified for Bulk Moulding Compounds (BMC). It was shown that the toughening modifier could participate in the curing reaction of the unsaturated polyester and construct different lengths of soft segments in the network, which has significantly increased the impact strength of the unsaturated polyester, whereas other mechanical properties such as tensile strength, flexural strength and modulus remain unchanged. The dynamic mechanical behavior of the cross-linked unsaturated polyester network was investigated by DMA.

Key words: Unsaturated polyester, Reactive polyethylene glycol, Toughening, Dynamic mechanical analysis(DMA)