Abstract: The hydroxy-terminated oligomeric polysiloxane(HO-PDM) grafted toughened phenolic resin was prepared by the copolymerization of HO-PDM with formaldehyde and phenol. The structure of modified phenolic resin was characterized by FT-IR. The mechanical properties of phenolic resin before and after modification were tested by the electron universal testing machine. The thermal stability of modified phenolic resin was analyzed with the thermal gravimetry. The elongation at break, impact strength, tensile strength of modified phenolic resin are estimated as 2.8%, 2.875 kJ/m2 and 23.2 MPa, respectively. The temperature of modified resin at 20% mass loss is 431.28 ℃, the peak temperature is 441.8 ℃, and the residual mass rate at 800 ℃ is 51.02%.

Key words: phenolic resin, polydimethylsiloxane, copolymerization