Application of Fourier transform infrared spectroscopy (FTIR) to investigation of moulding sands with furan resins hardening process

There were investigated some initial structural transformations which take place in ureafurfuryl binding systems. They were investigated by FTIR spectrometry. There were also used two different techniques: transmission and diffuse reflection (DRS). The spectra were recorded within a range of 400-4000 cm(-1). The subjects of studies were two modified urea-furan resins (Kaltharz F700 and Kaltharz U404U) and the hardening process with two activators. Changes in FTIR spectra during hardening of the resins were recorded after the time of 1, 2,4, 8 and 24 hours. In comparison there were also examined mechanical properties (tensile strength and bending strength) of sands prepared with these resins. Changes in the spectra of both resins with different activators were visible in the same range of 1400-1700 cm(-1) in about 2 hours since the moment of making the sand; then the number of the bands and their intesity were decreasing. From the conducted tensile and bending tests of the sand it follows that the highest increase of these parameters takes place within the time of up to 2 hours; then the strength increases but only slightly. As it follows from the preliminary studies, FTIR spectroscopy, and DRS technique - in particular, can be helpful in assessment of the hardening degree of moulding sands with organic binders and in getting familiar with the mechanism of the hardening process of these binders. There are also needed further investigations, especially to identify all the peaks in obtained spectrums.