Effect of humidity on the creep response of cellulose nanocrystals films
Cellulose nanocrystals (CNCs) are a derivative of cellulose, the Earth’s most abundant source of a sustainable polymer. There are many applications for CNCs such as batteries, antimicrobial films, flexible displays and drug delivery. This research is focused on CNCs films and the mechanical properties once humidity was introduced. The creation of self-aligned CNCs films was utilized to perform dynamic mechanical analysis (DMA) testing. The Forest Products Lab (FPL) in Madison, Wisconsin provided the CNCs used. Both 3.5 wt.% and 9.1 wt.% films were made and tested. A DMA method was created to test the creep response of the CNCs films at humidity levels of 80%, 40% and 0%. This method was performed at both 30°C and 50°C. Before and after the films were tested in the DMA, optical microscopy images were taken to analyze the structure of the films. It was found that the films experienced a higher strain rate at 30°C, but regardless of temperature the trend of strain was non-linear, with the highest strain reached at 80% humidity. There was full creep recovery at 40% humidity and shrinkage of the films once the humidity level reached 0%.
Youngblood, Purdue University.
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