Comparison of Nanofibrillated Cellulose and Hydroxyethyl Cellulose in Improving the Storage Stability of Waterborne Coatings

keywords:waterborne coatings  nanofibrillated cellulose  hydroxyethyl cellulose  yield stress  storage stability

Abstract:Waterborne coatings often delaminate and settle during long-term storage, requiring the addition of thickeners. The effects of nanofibrillated cellulose (NFC) and the commonly used thickener, hydroxyethyl cellulose (HEC), on the storage stability of waterborne coatings were compared in this study. The morphology of NFC was characterized using infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The rotational viscosity and rheological properties of the waterborne coatings with NFC and HEC were tested. Stationary settling experiments were also conducted at different temperatures to compare the difference of NFC and HEC on improving the storage stability of the waterborne coatings. The results showed that the waterborne coating with NFC exhibited pseudoplastic fluid characteristics; a small addition of NFC can achieve the same improvement effect on the storage stability of waterborne coatings as HEC. Further, the improvement effect of NFC was not affected by temperature. The waterborne coating with NFC still exhibited good storage stability at high temperatures, which was significantly superior to that of HEC. Therefore, NFC is a feasible agent for improving the prolonged storage stability and warming-induced delamination of waterborne coatings.