Rheological properties of waterborne polyurethane paints
writer：Huan-huan Zhang, Ran Niu, Xin-bing Guan, Dong-hua Xu*,Tong-fei Shi.
keywords：rheology, paints
source：期刊
specific source：Chinese Journal of Polymer Science
Issue time：2015年
The rheological properties of two specific waterborne polyurethane (PU) paints were studied by both macrorheological and microrheological methods. During the macrorheological measurement on a rotary rheometer, evaporation of solvent cannot be totally excluded, which has an influence on the reliability of rheological results. So, the linear oscillatory frequency sweep results (storage and loss modulus versus frequency) and steady shear results (viscosity versus shear rate) got from the rotary rheometer measurement are only used for qualitative analysis. As the evaporation of solvent can be neglected during microrheological measurements on a diffusing wave spectroscope (DWS), the results of storage modulus (G′) and loss modulus (G″) versus frequency are more credible than the results obtained from the rotary rheometer measurement. Thus, the results of G′ and G″ versus frequency from DWS measurements are used for quantitative analysis in this work. The G′ for both of the waterborne PU paints are larger than G″ at low frequency and that is opposite at high frequency in the experimental angular frequency range. The values of modulus at same frequency and viscosity at low shear rate for the two PU paints have apparent difference, which determines the difference of their application.