Abstract:

In this paper,epoxy resin-modified sulphonated waterborne polyurethane emulsions with a solid content of 50% were synthesized,with isophorone diisocyanate,hexamethylene diisocyanate and polyethylene glycol adipate diol as the main raw materials,and with 1,4-butanediol,N-( 2-aminoethyl) -amino ethane sulphonated sodium and epoxy resin E-51 respectively as the small-molecular chain extender,the hydrophilic chain extender and the
modifier. Then,the influences of epoxy resin content on the crystallization property of the cast films were investigated by means of FT IR, XRD, SEM, AFM, DSC and DMA. The results show that,with the increase of epoxy resin content,the two sharp diffraction peaks at 21.2° and 24.3° in XRD spectra are disrupted,the phase separation of the hard segment from the soft one of the cast films shown in SEM and AFM images is inhibited,distinct exothermic and endothermic peaks in DSC curve can be easily found,the relative crystallinity of the cast films decreases,and the glass transition temperature of the soft segment shown in DMA curves shifts to a lower value. All these abovementioned statements indicate that the addition of epoxy resin weakens the crystallization of the cast films.

Key words: sulphonate, waterborne polyurethane, epoxy resin, crystallization property