Cellulose Nanofibers Impart Melt Resistance to Ice through Optical and Thermal Mechanisms

Ice is ubiquitous in cold regions with historical significance as a key structural material. Contemporary efforts to leverage ice for the construction of large structures have incorporated cellulose-based reinforcing materials to increase strength. While an increased resistance to melting has been observed, it has not been investigated. Herein, we provide evidence that cellulose nanofibers (CNFs), as a heterogeneous component to synthetic ices, increase melt resistance through optical and thermal mechanisms. Specifically, we investigated the effect of 0.1–1.0 wt % CNFs on the reflectance, thermal conductivity, and melt rate of ice. The presence of CNFs increased reflectance of ice from 20 to 70% at 640 nm. Thermophysical measurements revealed that CNFs both slow melting and facilitate freezing and do not statistically affect the specific heat capacity of ice. Measurements with light flash analysis revealed that CNFs reduce thermal conductivity up to 10%. Overall CNFs reduced the melt rate of ice by 10× with only 1.0 wt % CNF. These results demonstrate that insoluble CNFs impart melt resistance to ice by both optical and thermal mechanisms, results that provide an interesting combination of controls for ice stability and formation to optimize ice material properties for high performance applications in cold regions.