Synthesis Of Azidized Polyurethane And Studr On Properties Of Polyurethane Matrix Composites

Thermoplastic polyurethane(TPU)is a polymer material with a wide range of applications.It owns the characteristics of both plastic materials and rubber materials.However,its poor thermal conductivity and electrical conductivity properties limit its application to some extent.Carbon nanotubes,as a kind of nano carbon materials,has been widely applied to preparation of polymer matrix composites.But in the process of preparing composites,carbon nanotubes is easy to reunite into polymer matrix and due to the inert surface of CNTs,and limits the performance of composites.So surface functionalization of CNTs before preparing composites is common measure to improve the dispersibility and compatibility in polymer matrix and the performance of composites.In this thesis,we prepared interface compatibilizers-azidized PU(APU),and we used APU to functionalize MWCNTs,then to prepare MWCNTs@APU/TPU composites.The mechanical,thermal conductivity and antistatic properties of the nanocomposites prepared by adding the TPU matrix were significantly improved.1.Under heating condition,the azide groups of APU could decomposed into nitrene structure which could combine with MWCNTs,the APU successfully wrapped onto the surface of MWCNTs(MWCNTs@APU),using Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy(Raman),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and thermogravimetric analysis(TGA)proved that azidized polyurethane was successfully wrapped in carbon nanotubes and between the two kind of structure macular which we designed originlly,the macular owns higher content of-COOH groups has better encapsulation effect on MWCNTs.2.The MWCNTs@APU/TPU nanocomposites were prepared by solution method.The SEM and AFM tests showed that the dispersion and interface compatibility of MWCNTs@APU in the TPU matrix were improved obviously,and the strength,thermal conductivity and antistatic properties of composites were improved greatly at the same time.When the addition amount of MWCNTs@APU in the composites is 2wt%,the maximum tensile strength of the composites is equivalent to 158%times of the pure TPU resin;when the addition amount is 3wt%,the electrical conductivity of the composite material reaches 4.23×10-6 s/cm,compared with the pristine MWCNTs/TPU composites,it is increased by 6 orders of magnitude;when the addition amount is 6 wt%,the thermal conductivity reached 0.4247 W/m.K,which is much higher than that of pure TPU resin.So in this thesis,we has prepared MWCNTs@APU/TPU composites with excellent mechanical,thermal conductivity and antistatic properties successfully.