IR Analysis of the Polyurethane Resins by a Modified Method

Abstract

Three moisture curable polyurethane resins with different NCO (isocyanate) contents were prepared by reacting a poly(tetramethylene ether) glycol (PTMEG) with excess Isophorone diisocyanate (IPDI), and they were characterized by the IR (infra red) spectroscopic analysis by a modified method with the quartz plate as the sample carrier. A quartz plate was scanned as the background in the FTIR in the range of 4000 to 2100 cm^(-1), and IR spectra of the moisture curable polyurethane resin coated quartz plates were scanned. In this IR range of 4000 to 2100 cm^(-1), the characteristic peaks of NH, CH and NCO groups of the polyurethane resins can be seen clearly. Thus, the use of the quartz plate as the sample carrier is proved to be successful in the IR analysis of the moisture curable polyurethane resins. The relationship between the relative absorbance of the resin coated quartz plate and the NCO content shows good linearity, indicating that the NCO content of the moisture curable polyurethane resins can be quantitatively determined by this modified method. It can be also seen that the quantitative analysis of the moisture curable polyurethane resins by this modified method is better than the conventional salt plate method.