Time-Dependent Elastic Tensor of Cellulose Nanocrystal Probed by Hydrostatic Pressure and Uniaxial Stretching

Abstract

The elastic properties of crystals are fundamental for structural material. However, in the absence of macroscopic single crystals, the experimental determination of the elastic tensor is challenging because the measurement depends on the transmission of stress inside the material. To avoid arbitrary hypotheses about stress transfer, we combine hydrostatic pressure and uniaxial-stretching experiments to investigate the elastic properties of cellulose I β . Three orthogonal compressibilities are 50.0, 6.6, and 1.71 TPa −1 . Combining Poisson's ratios from a uniaxial stretching experiment directly gives the Young's modulus along the chain direction (E 33 ). However, Poisson's ratio depends on the deformation rate leading to apparent modulus E 33 = 113 GPa using a slow cycle (hours) and 161 GPa using a fast cycle (minutes). The lattice deformation along the chain is not time-dependent, so the off-diagonal elements are time-dependent on the scale of minutes to hours.Letter pubs.acs.org/JPCL

Quantifying the Contribution of the Dispersion Interaction and Hydrogen Bonding to the Anisotropic Elastic Properties of Chitin and Chitosan

“…The experimental estimates for chitin and chitosan by Nishino et al look reasonable especially as the f -values, i.e., the modulus multiplied by the chain cross-sectional area, are similar. Also in previous DFT calculations on crystalline cellulose, moduli were high compared to the static deformation experiments, , and the simulated Poisson’s ratio was low even in classical MD calculation . Thus, there are definitely limitations for both DFT and classical MD approaches.…”

“…Simulated moduli are indeed much higher than experimentally determined values (41 and 59.3 ± 11.3 GPa and 65 GPa, using two different X-ray techniques). This difference is probably related to the low off-diagonal elements calculated by DFT . In reality, when the fibril is stretched in the axial direction, the lateral dimension decreases to keep the volume unchanged, and thus the energy increase is attenuated.…”

“…This difference is probably related to the low off-diagonal elements calculated by DFT. 26 In reality, when the fibril is stretched in the axial direction, the lateral dimension decreases to keep the volume unchanged, and thus the energy increase is attenuated. This process is probably slow, and the molecular deformation to accommodate the available space might be incompatible with strict periodicity in all directions.…”

“…The experimental Poisson’s ratio was obtained from the displacement of the diffraction spots in previous studies of crystal moduli measurements . The X-ray diffraction strain measurement of β-chitin was carried out by using extracellular crystalline filaments from Thalassiosira weissflogii embedded in PVA, following the same protocol and analysis as a recent study on cellulose . The strain of d -spacings of equatorial spots with respect to the strain meridian spots is also shown in Figures S1 and S2.…”

Anionic polymerization of nonaromatic maleimide to achieve full-color nonconventional luminescence

“…The pressure was manually adjusted through a screw rod and balanced for 5 min. Then the fluorescent spectra and confocal images of A-PM-TEA under different hydrostatic pressures were acquired 54 .…”