Preparation And Properties Of Epoxy/Polyurethane/Montmorillonite Composites

In this paper,polyurethane prepolymer(PUR)and epoxy resin(EP)were blended by solution blending,and then cured with diaminodiphenyl sulfone(DDS)to prepare EP/PUR castings with different PUR contents.It is characterized by Fourier transform infrared spectroscopy(FTIR),dynamic mechanical properties(DMA),thermogravimetric(TGA),scanning electron microscopy(SEM),limiting oxygen index(LOI),and mechanical properties such as bending,tensile,and impact.The results of FTIR showed that the groups before and after the mixing of PUR and EP did not change significantly,which belonged to physical mixing.The analysis of the cured product showed that both of them had solidified completely.The mechanical properties show that when the PUR content is 25%,the impact strength of the EP/PUR system is optimal,and the impact performance of the EP is increased by 2 times,but the bending and tensile strength are reduced to different degrees.The DMA results show that with the increase of PUR content,the storage modulus of EP/PUR system decreases and the glass transition temperature decreases.The impact fracture morphology can be seen by SEM.The fracture morphology of EP/PUR is more rough than that of EP.The fractures are more wrinkles,the texture is finer,and the actual surface area of the fracture surface is larger.It is a typical peak ductile fracture.The results of TGA showed that the thermal decomposition temperature of EP/PUR system decreased slightly with the increase of PUR content;the LOI value showed that the value decreased slightly with the increase of PUR content.The montmorillonite(MMT)was intercalated with octadecyl ammonium bromide(CTAB)and characterized by infrared and X-ray diffraction.The intercalation was successful and the interlayer spacing was expanded.The EP/PUR-OMMT composites with different content of montmorillonite were prepared by organic intercalation modification of montmorillonite by monomerintercalation-in-situ polymerization.Same as above,FTIR results show that EP/PUR-OMMT composites are completely cured.XRD results show that montmorillonite exists in the form of exfoliation in EP/PUR-OMMT composites with montmorillonite content of 1% to 3%,In EP/PUR-OMMT composites with montmorillonite content of 3%to 5%,montmorillonite exists in the form of intercalation-peeling.The mechanical properties show that when the content of montmorillonite is 3%,its comprehensive mechanical properties are the best,its impact strength is three times higher than that of PUR-EP,and it is doubled compared with EP/PUR,and its bending and tensile strength are also obtained Increase.The DMA results show that when the content of montmorillonite is3%,the storage modulus is the largest,but the glass transition temperature is the lowest.Through the SEM analysis of the impact fracture,it can be seen that the sections have obvious lamellar structure.These lamellar structures increase a large number of fracture surface areas,and the fracture cracks are more tortuous and complicated,so the impact performance of EP/PUR-OMMT system can be obtained.Greatly improved.The TGA results show that with the increase of montmorillonite content,the thermal decomposition stability of EP/PUR-OMMT composites is improved,and the amount of residual carbon is also increased;LOI results show that with the content of montmorillonite Increasing its value becomes larger,indicating that montmorillonite has a good flame retardant effect.