Preparation And Properties Of Polycap-Rolactone/Polydimethylsilioxane/Epoxy Resin Composites

Silyl-terminated polyprolactone/polydimethysiloxane (PCL-TESi/PDMS-TESi) was directly synthesized via -OH and -NCO nucleophlic addition reaction.Epoxy resin (EP) was then modified with the PCL-TESi/PDMS-TESi oligomers.The modified system was cured with amino curing agent via amoni-glycidylreaction and Sol-gel process at different oligomer/epoxy ratio.The morphology of composites system was investigated by Scanningelectron microscopy (SEM), Transmission electron microscopy(TEM), andEnergy disperse spectroscopy(EDS). The results showed that toughness of themodified epoxy resin was evidently improved when different content ofPCL-TESi/PDMS-TESi oligomer was added. The phase structure of themodified composite changed from separated phase, via co-continuous phase, tophase inversion with increasing PCL-TESi/PDMS-TESi content, where thephase formed by PCL-TESi and PDMS-TESi dispersed in continuous EP phase,when ratio of PCL-TESi/PDMS-TESi and EP was smaller than 4:6 (wt%), andthe dimension of dispersed phase gradually increased with increasingPCL-TESi/PDMS-TESi content. Furthermore, when the ratio was between 4:6 and 6:4, phase structure changed to Inter-penetrating Network (IPN) via thehydrolysis, condensation of-Si(OR)₃ and amoni-glycidyl reaction.Thermal decomposition properties of the cured composites were studied byTGA and DTG, the results of which indicated that initial decompositiontemperature (defined as temperature at 5% weight loss) decreased at first andthen gradually increased with increasing PCL-TESi/PDMS-TESi content. Theinitial decomposition temperature was 309.7℃at PCL-TESi/PDMS-TESi:EP=5:5, higher 153.9℃than pure epoxy resin.The surface tension of composite system was obtained based on the contactangle via Owens-Wendt-Kaelble model. The results showed that the surfacetension decrease with the increasing of PCL-TESi/PDMS-TESi content.However, the composites cured at 50℃had a higher surface tension than thatcured at room temperature. At the same time, the distribution of Si element atthe composites surface was studied by X-ray photo spectroscopy, confirmingthat Si element migrated toward surface to some extent.Corrosion resistance properties of the composites were also studied. Theresults showed the composites had a little change of mass change generally,indicating that they had a good anti-corrosion performance. But water-resistance,acid-resistance and salt-resistance increased after decreasing a little with theincreasing of PCL-TESi/PDMS-TESi content and reached a peak atPCL-TESi/PDMS-TESi:EP=5:5. But the base-resistance properties graduallybecame worse with increasing PCL-TESi/PDMS-TESi content. All of research methods, experimental data and results in the paper arebenefit to modify epoxy resin in the future.