Mechanical and thermal properties of epoxy resin modified by polysiloxane with different side groups
The epoxy resin were modified by hydroxyl-terminated dimethylsiloxane(PDMS)and phenylpropylsiloxane(PPPS).The effects of different polysiloxanes on the structure and properties of epoxy resin were studied by infrared spectroscopy,nuclear magnetic resonance spectroscopy,mechanical property and thermal property tests.The results showed that both PDMS and PPPS were copolymerized with epoxy resin.The tensile strength of the two modified resins increased firstly and then decreased with the increase of polysiloxane amount.When the mass fraction of PPPS was 20％,the tensile strength and impact strength of PPPS/EP were 45.7％and 30％higher than those of pure epoxy resin,respectively,and the strength and toughness of epoxy resin were improved at the same time.The impact strength of PDMS/EP was increased by 118％.The re-sults of fracture morphology showed that the phase structure of island morphology was produced in both resins,and the phase structure size of PPPS/EP was smaller than that of PDMS/EP.Both polysiloxanes could improve the thermal stability of epoxy resin.The PPPS/EP had better heat resistance and higher carbon residue rate,and the carbon residue rate could reach 15.7％at 1 000 ℃.
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