| Autor: |
Leo F. Munier, Tom Franke, Nadine Herold, Alexander Pfriem |
| Rok vydání: |
2020 |
| Předmět: |
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| Zdroj: |
BioResources. 15:1563-1574 |
| ISSN: |
1930-2126 |
| DOI: |
10.15376/biores.15.1.1563-1574 |
| Popis: |
The dynamic-mechanical behavior of phenol-formaldehyde-impregnated beech wood (Fagus sylvatica L.) veneers was evaluated at various relative humidities. The aim was to identify the plasticizing effects of moisture on phenol-formaldehyde-impregnated veneers. Thin beech veneer samples were impregnated with a low and a medium molecular weight phenol-formaldehyde resin. The measurements were performed with a dynamic-mechanical thermal analysis equipped with a humidity generator. The storage modulus and the loss factor of the uncured phenol-formaldehyde-impregnated and the untreated control veneers were determined at a relative humidity of 15%, 60%, and 85% and a constant temperature of 25 °C. The untreated control veneers exhibited the smallest reduction of the normalized storage modulus. In contrast, the phenol-formaldehyde-impregnated samples exhibited a more intense relative reduction of the storage modulus with increasing relative humidity. This effect was more distinct for samples impregnated with low molecular weight phenol-formaldehyde than for those impregnated with medium molecular weight phenol-formaldehyde. In addition, higher solids contents in the resins led to even smaller normalized storage modulus. Consistently, the loss factor indicated a greater softening of the samples with an increasing humidity and higher solids content of the phenol-formaldehyde. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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