Erik Larnøy
Seniorforsker
Sammendrag
Non-destructive and rapid analysis of adhesive penetration in engineered wood products ensures bond integrity, enabling the development of novel adhesives and quality manufacturing. The present study evaluated the X-ray densitometry method for studying the adhesive penetration in birch plywood. In this approach, it was quantified as a function of distance by measuring the X-ray density profile section where the adhesive bond-line density was above the baseline wood density. Accordingly, untreated and esterified birch veneers were pressed into plywood using both liquid and solid-type phenolic adhesives, resulting in four types of five-layered plywood of 7-8 mm in thickness. Optimization of X-ray beam attenuation through the plywood was done by preliminary trials and identified the specimen dimensions as 50 mm in height and 25 mm in width using a scanning speed of 0.5 mm min $$^{-1}$$ . The X-ray densitometry measured densities of cured phenolic adhesive to be 1150 ± 50 kg m $$^{-3}$$ and esterification-modified birch plywood to be 750 ± 25 kg m $$^{-3}$$ . These density values are consistent with gravimetric density measurements. Density profile observations indicate that both liquid and solid forms of phenolic adhesives exhibited similar levels of adhesive penetration in plywood. X-ray densitometry analysis determined a total interphase thickness ranging from 0.50 to 0.75 mm, encompassing the central adhesive bond-line and the effective adhesive penetration into both adjacent veneers. These values are comparable with those measurements obtained from microscopy imaging analysis. Therefore, X-ray densitometry could be a swift method for quantifying adhesive penetration, although further studies are needed to validate its accuracy and reliability.
Forfattere
Andrea Ponzecchi Albin Lobo Claudia Cocozza Paolo Cherubini Matthias Saurer Erik Larnøy Lisbeth G. ThygesenSammendrag
Broadleaf afforestation increasingly requires planting material that combines valuable wood properties with resilience to climatic stress. High heartwood content is a desirable trait in pedunculate oak (Quercus robur), but it is unclear whether selecting for it could be a trade-off with resistance and resilience to drought. We addressed this question in a 24 year old progeny trial in southern Denmark where trees were ranked by heartwood production and the 2018 drought was used as a natural stress event. Trees with contrasting heartwood content were assessed using multiple indicators of drought response, including annual ring width, vessel anatomy, wood density, and dual stable isotopes (δ¹³C and δ¹⁸O) measured separately in earlywood and latewood over a five-year period. The 2018 summer drought was of moderate intensity at the trial site, with SPEI3 approximately −1.5, but it was clearly reflected in isotopic signals, indicating that trees perceived the water deficit. In contrast, radial growth did not decline, and ring widths remained above average in 2018. Across all metrics, trees with lower and higher heartwood content showed broadly similar physiological and wood-structural responses. Within the environmental conditions and drought intensity observed in this study, our results provide no evidence for a strong trade-off between heartwood content and response to a drought of moderate severity. They therefore support, with appropriate caution, the continued consideration of heartwood content as a selection trait in breeding and afforestation programs in comparable environments.
Forfattere
Erik LarnøySammendrag
På oppdrag fra Norges Fotballforbund (NFF) har NIBIO undersøkt innholdet av sink i korkgranulat brukt som innfyll på kunstgressbaner. Korkprøver fra to baner i Oslo (Rustad og Bjørndal) ble sammenlignet med fabrikkny kork fra Amorim og naturlig vinkork. Analysene viste at korkgranulat fra banene inneholdt noe mer sink enn referanseprøvene, men nivåene var lave, med målte verdier fra 8,5 til 32,6 mg/kg. Alle verdiene ligger betydelig under nasjonale og internasjonale terskelverdier som benyttes ved vurdering av forurenset jord. Resultatene indikerer at korkgranulatet over tid påvirkes av omgivelsene gjennom opptak av mineraler og salter fra banen og nærliggende miljø. Høye nivåer av natrium bekrefter påvirkning fra vintervedlikehold og salting. For å undersøke om saltingsmidler kunne forklare de forhøyede sinknivåene, ble to produkter som brukes på kunstgressbaner analysert. Begge viste svært lave innhold av sink, og salting vurderes derfor ikke som kilden til de målte sinknivåene. På bakgrunn av de gjennomførte analysene vurderes sinkinnholdet i korkgranulat som uproblematisk.
