Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2019
Forfattere
Charlotte Grosse Warren J. Grigsby Marion Noël Andreas Treu Marie-France Thévenon Philippe GérardinSammendrag
When exposed to moisture, wood undergoes swelling and is susceptible to fungal degradation. Chemical modification via oligomeric lactic acid (OLA) treatment has been found to be a promising environmentally friendly solution to this disadvantage. In this study, wood was impregnated with OLA and then variously heat treated to polymerize the OLA in situ. The effect of curing temperature and time on OLA polymerization has been determined chemically. Dimensional stability was examined by water immersion and hygroscopicity measurements and biological decay resistance also evaluated. OLA impregnation followed by heat treatment enhanced wood properties. OLA cure at 160 °C for 48 h resulted in treated wood with greater dimensional stability and biological resistance.
Forfattere
Lone RossSammendrag
Det er ikke registrert sammendrag
Forfattere
Lone RossSammendrag
Det er ikke registrert sammendrag
Sammendrag
Surface mould growth contributes to the colour changes of outdoor exposed wood over time. Modelling mould growth can thus help visualize wooden facades’ colour development, which can improve facade design and service life. However, existing wood mould models do not consider transient wetting effects that occur outdoors due to precipitation and condensation. To address this, four mould models were evaluated using laboratory experimental data that included exposure to transient wetting. First, the models (the original and the updated VTT model, the biohygrothermal model and the mould resistance design (MRD) model) were evaluated for Scots pine sapwood. For this evaluation, the transient wetting effect was implemented in the models by using hourly wood surface relative humidity (RH), calculated from electrical resistance measurements, as input. This showed that the original and the updated VTT model gave best fit to the experimental data. However, further evaluation of these two models for more wood materials showed that the updated VTT model was sensitive to the choice of material parameters. Large discrepancies occurred when varying the material parameters in the updated VTT model. Finally, different estimates of RH were tested in the original VTT model. Using wood surface RH as input gave best fit to the experimental data, and ambient air RH gave poorest fit. Overall, the results indicate that the original VTT model is fairly reliable and can be used to predict mould growth on wooden claddings exposed to transient wetting as long as the wood surface climate is used as climatic input data.
Forfattere
Lone RossSammendrag
Det er ikke registrert sammendrag
Foredrag – My experience with COST networks – cooperation, scientific boost and friendship
Lone Ross
Forfattere
Lone RossSammendrag
Det er ikke registrert sammendrag
Sammendrag
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Sammendrag
Laboratory screening tests are commonly used to indicate wood materials’ resistance or susceptibility to surface mould growth, but the results can deviate from what happens during outdoor exposure. In this study, the aim was to investigate how well agar plate screening tests and water uptake tests can predict mould growth on exterior wooden claddings. The tested wood materials included Norway spruce heartwood (Picea abies), sapwood and heartwood of Scots pine (Pinus sylvestris), aspen (Populus tremula), acetylated Radiata pine (Pinus radiata) and DMDHEU-modifed Scots pine sapwood. The agar plate test included four inoculation methods (two monoculture spore suspensions of Aureobasidium species, one mixed-culture spore suspension, and inoculation from outdoor air) and three incubation temperatures (5, 16 and 27 °C). Inoculation method and incubation temperature had signifcant efects on the mould rating in the agar plate screening test, but none of the agar plate test combinations gave good indications of outdoor performance. Results from the agar plate test gave signifcantly negative correlations or no signifcant correlation with results from the outdoor test. However, the water uptake test gave signifcantly positive correlations with outdoor mould rating, and could be a useful indicator of susceptibility of uncoated wooden claddings to surface mould growth.
Sammendrag
This study addresses changes in visual appearance of unpainted wood materials exposed outdoors. Specimens of aspen (Populus tremula), Norway spruce (Picea abies), untreated Scots pine (Pinus sylvestris), DMDHEU-modified Scots pine and acetylated Radiata pine (Pinus radiata) were exposed facing south in Ås, Norway for 62 weeks. During this period, mould growth coverage, lightness (L*) and the uniformity of the weather grey colour were assessed. Mould growth coverage was evaluated visually using a rating system. L* and the uniformity were evaluated using image analysis. The increase in mould rating of the wood materials developed in varying speed, but all specimens had reached the maximum rating after 42 weeks. Until then, the changes in L* correlated significantly with the mould rating. However, the specimens continued to darken after they had reached maximum mould rating. DMDHEU was the only material that obtained a more uniform colour as a consequence of the weathering.
Sammendrag
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