| The polyurethane adhesive contained large amount of polar groups, the hydrogen bond could be formed and the material could be bonded due to hydrogen bonding. This adhesive not only possessed a series of advantages, but also some disadvantages, such as poor temperature resistance and poor corrosion resistance. To its shortcoming, a lot of research had been carried on domestic and foreign, the vast majority was use a substance to improve the defects, but this way could not enhance its comprehensive performance. Although it could expanded the field of application, there were limits. In this paper, selection of epoxy resin, acrylic polyurethane to improve the performance of PU, a IPN structure and semi IPN structure adhesive are synthesized, and the corresponding content adjusted to explore the corresponding rules, to determine a good adhesive.PU adhesive had been synthesized by prepolymer method to which were included the unmodified PU adhesive, PU/epoxy interpenetrating polymer networks(IPN) adhesive, PU/epoxy/acrylate IPN adhesive. The variety of the modifier and the solid content were adjusted to obtain the variation of the properties. The results showed that:(1) when the solid content is 70%, PU adhesive no modified has low tensile strength is19.10 MPa, tensile and shear strength of 0.27 MPa, the initial thermal decomposition temperature is 244.6℃, no obvious phase separation were observed under the scanning electron microscope(SEM), and the acid corrosion resistance is poor, under the condition 50%H2SO4 and 75℃(following acid corrosion test conditions were the same), the specimen surface began to change obviously after 5h.(2) When the solid content is 70%, PU adhesive is modified by E-51, the tensile strength is 27.32 MPa, the tensile shear strength is 1.14 MPa, as well as initial decomposition temperature is 262.3℃. The SEM images in which the phase is slightly separated showed that its acid corrosion resistance is improved significantly, PU adhesive specimens have obviously changed after 10 h.(3) When the solid content is 70%, the PU adhesive is modified by E-51 and acrylate, the tensile strength is 25.02 MPa, tensile shear strength is 7.02 MPa, initial thermal decomposition temperature is 266.2℃,under the SEM we can see obvious phase separation and distribution, the acid corrosion resistance is improved, the surface changes after 72 h.(4) When the solid content is 80%, PU adhesive is modified by E-51, acrylate, the granular not suitable for coating adhesives, tensile strength is 12.30 MPa, initial thermal decomposition temperature is 263.0℃. The surface showed in SEM image. is obviously changed in phase separation obviously after 48 h with soaking in acid.In the synthesis of 70% modified PU transform, it is get the best condition for the corresponding physical mechanical, adhesive properties and TG, DSC, acid resistance, water resistance when the content of AIBN, the content of NCO and the content of E-51 were changed respectively. The test data showed that it has the best performance, the tensile strength is 25.02 MPa, the tensile shear strength is 7.02 MPa, the initial decomposition temperature is 266.2℃, the interior has a relatively uniform phase separation, the surface has obvious change after 72 h when the solid content is 70%, the AIBN is 1% of the total mass of acrylic and NCO content of 4%, E-51 is 20 g,PU adhesive was synthesis with semi IPN structure and non-solvent, and when exploring with the NCO content changing and the chain extension agent E-51 and DADMT ratio is not the same, their various performance changes. Experimental results showed that: when in the ratio of m(MMA+BMA) and m(E-51) is 1:3.5, the ratio of E-51 and DADMT is 1:2.5, the NCO content is 7%, it has a good resistance to corrosion, physical mechanical properties and adhesive properties, but at this time the resistance temperature is the lowest. And from the SEM, the internal dispersion is more uniform, there is a more obvious phase separation. |
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