Porosity of wood pulp fibers in the wet and highly open dry state
| Autor: | Tapani Vuorinen, Pegah Khanjani, Thaddeus Maloney, Ville Lovikka, Saija Väisänen |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
02 engineering and technology
engineering.material 010402 general chemistry 01 natural sciences chemistry.chemical_compound Nitrogen adsorption stomatognathic system General Materials Science Cellulose Dissolving pulp Porosity ta216 Dissolution Chromatography Pulp (paper) Sorption General Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 0104 chemical sciences stomatognathic diseases chemistry Chemical engineering Kraft process Mechanics of Materials SEM engineering 0210 nano-technology Critical point drying Kraft paper |
| Zdroj: | MICROPOROUS AND MESOPOROUS MATERIALS. 234:326-335 |
| ISSN: | 1387-1811 |
| DOI: | 10.1016/j.micromeso.2016.07.032 |
| Popis: | The porosity of kraft and dissolving pulp samples with different drying histories were studied in the wet (Water Retention Value, Solute Exclusion) and dry state (N 2 sorption, Scanning Electron Microscopy) and the results were compared. An efficient drying protocol was created to minimize porosity loss upon water removal for dry analyses. The samples were first solvent exchanged by dialysis to dry acetone and then critical point dried (CPD) from CO 2 . It was found out that even after reaching relatively high specific surface areas of 200–300 m 2 /g for CPD pulp, the samples had shrunk and most of the micropores were not detectable until rewetting. However, the dry state mesoporosity correlated well with the wet state values. SEM was used to examine the pore structure and fibril arrangement of the CPD fiber sample. The kraft pulps were found to have a larger specific pore volume and surface area than the dissolving pulps as measured by N 2 sorption. However, SEM analysis of the samples showed the dissolving pulps had a more homogenous and more open surface porosity than the kraft samples. The kraft pulp showed less hornification after drying and rewetting than the dissolving pulp. Heating of kraft pulp to 100 °C during drying increased the irreversible pore closure. Pores were often arranged in chain-like formations and signs of surface fibril aggregation were detected. |
| Databáze: | OpenAIRE |
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