利用ATR-FTIR定量测定聚氨酯预聚体的异氰酸酯基含量

Quantitative determination of isocyanate group content in polyurethane prepolymer by ATR-FTIR

对于多苯基多亚甲基多异氰酸酯与聚醚多元醇制备的聚氨酯预聚体系列样品进行衰减全反射傅里叶变换红外(ATR-FTIR)测试,分别用异氰酸酯基团(-NCO)的红外特征峰(~2245 cm^(-1))的吸光度A和校正峰面积S与电位滴定法得到的-NCO含量进行线性拟合。结果表明,后者的线性关系优于前者,相关系数R 2分别为0.9967和0.9856。依据校正峰面积S对-NCO含量之间的工作曲线,测定了新制备预聚体的-NCO含量,与电位滴定法相比,相对误差均<0.2%,相对标准偏差均<0.5%,表明测试准确度良好,方法可靠。利用ATR-FTIR测定聚氨酯预聚体的-NCO含量,样品无需任何前处理且用量少,不产生废液、环境友好,测试结果可靠;便于在工业生产现场进行操作和应用。

Attenuated total reflection Fourier transform infrared(ATR-FTIR)tests were performed on a series of polyurethane prepolymer samples prepared from polymeric methylene diisocyanate(pMDI)and polyether polyol.The absorbance A of the infrared characteristic peak(~2245 cm^(-1))and the corrected peak area S of isocyanate group(-NCO)were used to linearly fit with the content of-NCO obtained by potentiometric titration,respectively.The results showed that the linear relationship of the latter was better than the former,the correlation coefficients R 2 were 0.9967 and 0.9856,respectively.According to the working curve between the corrected peak area S and the content of-NCO,the content of-NCO of newly prepared prepolymers were determined.Compared with the potentiometric titration method,the relative error of new working curve was<0.2%,and the relative standard deviation was<0.5%,indicating that the test accuracy is good enough and the method is reliable.As ATR-FTIR is used to determine the-NCO content of polyurethane prepolymer,the sample does not need any pretreatment and volume of samples are tiny.In this way,it does not produce waste liquid and is environmentally friendly.The test results are reliable,and it is convenient for operation and application in industrial production site.