PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 8, Number 3, 2022
WOOD PANEL “Comparative analysis of very volatile organic compounds and odors released from decorative medium density fiberboard using gas chromatography–mass spectrometry and olfactory detection”, Weidong Wang, Jun Shen, Ming Liu, Wang Xu, Huiyu Wang & Yu Chen, Chemosphere , Vol.309, Part 1, 136484 (Dec. 2022). VVOCs with a retention range below C6 have become one of the main indoor pollutants that negatively affect human health. Most studies have focused on the emission of VOCs from furniture and decorative materials, seldom consider VVOCs. To close this gap, a 15-L environmental chamber, combined with multi-absorbent tube, was used for gas sampling. Emissions of VVOCs and odors released from decorative medium density fiberboard (MDF) were measured using gas chromatography–mass spectrometry and olfactometry detection. The results demonstrated that multi-absorbent tubes had excellent capture capacity for low-molecular-weight VVOCs. Thickness and decorative materials had conspicuous effects on VVOCs and odor emissions. The total VVOCs (TVVOC) from 18- mm decorative MDF was consistently higher than that of 8-mm samples. The major VVOCs from these decorative MDF were alcohols, esters and ketones, which were the major odor contributors with high odor intensity values. VVOCs concentration generally increased as thickness increased, but it decreased after decorative treatment. Fruity and alcohol-like were the main odor impressions of 8-mm MDF, whereas sweet and fruity were the major odor impressions of 8-mm polyvinyl chloride decorative MDF (PVC-MDF) and melamine impregnated paper decorative MDF (MI-MDF). Fruity was the main odor impression of 18-mm decorative MDF. The overall odor intensity increased and the major odor impression may differ when thickness was changed. Both the MI and the PVC decorative materials blocked some odor emissions but did so to a greater extent with the former than with the latter. Identification and analysis of the composition of VVOCs can supplement a database structure network of volatile pollutants and establish a novel and feasible method to investigate low-molecular-weight substances from wooden materials and their products. “Multiscale analysis of water vapor diffusion in low density fiberboard: Implications as a building material”, Patrick Perré, Romain Rémond & Giana Almeida, Construction and Building Materials , Vol.329, 127047 (25 Apr. 2022). This work is devoted to diffusion mechanisms in low-density fiberboard (255 kg m í ). Experiments were performed under unsteady state conditions (relative humidity step from 37% to 71%) with different thicknesses (half thickness ranging from 1 mm to 20 mm). The mass diffusivity was determined by inverse analysis from the experimental moisture content evolution, using a comprehensive macroscopic model of coupled heat and mass transfer. A clear failure of Fickian’s law becomes evident regarding the effect of thickness. A dual-scale model, based on the concept of distributed microstructure models with coupled heat and mass transfer at both scales, was used to simulate the experiments. The large number of dual-scale simulations proposed in this work were also analyzed by the inverse method. These dual-scale simulation results were successfully confronted to the experiment. The good fit with the experimental data is obtained for a diffusivity of the microscopic phase WKHVWRUDJHSKDVH HTXDOWRí m 2 s í for a fiber radius of 20 μm. As the main recommendation, we advise that the dual scale effect can be neglected for this kind of fiberboard for a total thickness larger than some centimeters, depending on the panel density. This also means that this effect must be considered in material characterization or when capturing the buffering effect of the surface layers of the envelope.
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Technical Abstracts
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