Comparative analyses of thermal transport in cellulose at crystalline, paracrystalline and amorphous states

Cellulose exhibits distinct phase characteristics across its crystalline, paracrystalline, and amorphous states. While prior studies have established correlations between condensed states and thermal properties in inorganic materials, the fundamental mechanisms governing heat transfer in polymers, particularly regarding phase transformations, remain poorly understood. Through molecular dynamics simulations, we quantitatively characterize the progressive loss of long-range order during crystalline-paracrystalline-amorphous transition of cellulose and elucidate its profound impact on thermal transport suppression. Our in-depth phonon analyses reveal synergistic mechanisms driving this reduction: diminished mid-frequency phonon contributions, enhanced phonon localization, intensified scattering processes, and reduced phonon lifetimes and group velocities. This work sheds light on the fundamental mechanisms of thermal transport during polymer phase transformations and offers valuable insights for the design and application of cellulose-based functional materials, particularly in thermal management applications.