Morphologies and mechanical properties of unsaturated polyester resin modified with TDI

The morphology, mechanical properties of unsaturated polyester(UP) resin modified with TDI were studied via dynamic FT-IR spectra, SEM, DMA and mechanical property testing. Results show that companying with the cured cross-linking reaction of UP resin, TDI can firstly react with UP and produce polyurethane(PU), and then UP and PU form the cross-linking nets together. The impact fracture section morphology of modified UP resin manifested the typical sea-islands structure. Testing of mechanical properties showes that for introducing of PU, the TDI has an obvious effect on the toughness and strength of UP resin. When the ratio of TDI/UP (w/w) was 7.5%, the modified UP resin exhibited the best mechanical properties with flexural strength of 125 MPa, impact strength of 18 kJ·m−2 and tensile strength of 72 MPa.