(317b) Diffusion-Softening of a Mechanically Adaptive Cellulose Nanocrystal Polyurethane Composite
We explore the dynamics of the mechanical softening upon exposure to water and develop a relationship between storage modulus and water diffusion as functions of filler loading. Dynamic mechanical analysis (DMA) coupled with a relative humidity accessory enabled direct evaluation of the mechanical adaptivity in response to the water stimulus and thermogravimetric analysis â sorption analysis (TGA-SA) was implemented to evaluate the diffusivity of water in a high relative humidity environment. Following a hindered diffusion model, the ratio of bound-unbound water was characterized for its impact on mechanical softening providing new insight into the softening kinetics. Finally, an empirical relationship between water and filler concentration on storage modulus was developed and compared to existing theories such as Halpin-Kardos, and percolation theory.