Formaldehyde diffusion within crystalline and amorphous cellulose at different temperatures and electric fields: A molecular dynamics study

Abstract

To provide a microcosmic theoretical support for the reduction of formaldehyde in building material, the diffusion process was investigated by molecular dynamics simulation. In addition, the diffusion model of formaldehyde molecules in crystalline and amorphous cellulose was built, and diffusion coefficients at different temperatures and electric fields were studied. The simulation temperature was from 293 to 393 K and electric field was from 0 to 400 kV/m. Diffusion coefficient increased with greater temperature and electric field both in crystalline and amorphous region. However, the diffusion coefficient in amorphous region could be ignored for it was two orders of magnitude lower than diffusion coefficient in crystalline region. The relationship between diffusion coefficient and temperature, and the relationship between diffusion coefficient and electric field were obtained by simulation, verified by the experiment. Temperature was shown to have a significant contribution to formaldehyde diffusion than electric field. Compared with experimental studies, the molecular dynamics simulation could only analyse the diffusion coefficient qualitatively because of the difference between micro-scale and macro-scale.

Wood–Moisture Relationships Studied with Molecular Simulations: Methodological Guidelines

“…As for adsorption properties, in their molecular simulation of adsorption of various absorbates in cellulose, Da Silva Perez et al [73] found that the heat of adsorption for a large variety of aromatic compounds is consistent with experimental values; 84% of the adsorbate-cellulose couples displayed differences of less than 20% between the measured and predicted heats of adsorption. Xu and Chen [74] also found that PCFF predicts formaldehyde diffusion in cellulose showing a temperature-dependent self-diffusion coefficient in good agreement with experimental data. Overall, the research presented above shows that the PCFF forcefield can provide a reasonable, at least semi-quantitative, description of cellulose in terms of its density, mechanical, and adsorption properties.…”