American researchers have developed a heating and cooling process that makes wood porous, paving the way for its use as thermal and acoustic insulation.
Tenfold insulating properties
Yes bois is one of the most durable building materials, it is generally considered a poor insulator. In the context of work published in the journal Nature SustainabilityLiangbing Hu and colleagues at the University of Maryland set out to change that, boiling it in a solution of sodium hydroxide (to remove lignin and hemicelluloses) and then letting it dry at room temperature for seven hours.
Such a process resulted in the formation of tiny cavities less than 10 micrometers in diameter, reducing the density of the material from 0.27 grams to just 0.11 grams per cubic centimeter and tripling its ability toisolation insulation, now equivalent to that of expanded polystyrene foam (EPS), commonly used in the building sector.
The study authors also found that the new material retained much of the strength of the original wood: tests showed it to be around seven times stronger than EPS foam, meaning it could be used as a combined structural component and insulator.
Treated wood was also found to be 10 times more effective at blocking sound than its untreated counterpart, when tested at frequencies between 500 and 2,500 hertz. According to Hu, this material has the potential to reduce carbon emissions associated with the construction of new housing, as it could replace foam made from petroleum, while reducing subsequent environmental damage.
A material that degrades safely in a few months
If the experiments performed involved paulownia wood (Paulownia tomentosa), a fast-growing tree found around the world, Hu says a wide range of species, including balsa, linden and pine, could also be suitable.
« Disposal or landfill of synthetic materials, especially polymeric foams, at the end of their lifecycle can pose environmental challenges, as most plastics take hundreds or even thousands of years to degrade due to the stability of the long polymer chains “, explains the scientist. ” Our wood insulation degrades safely within months. »