One aim of this work program was to select the torrefaction parameters for which durability is largely improved with the maintain of acceptable values for mechanical properties. For this, it was necessary to establish << prescriptions >> involving a lot of tests usually carried out to qualify a given wood species with or without chemical treatment.
Thus, physical properties were defined first, followed by mechanical properties and durability to biological agents tests.
For industrialization purposes, paintability, gluability and processing tests were also carried out. A test of resistance to fire was also done.
At last, to be sure that torrefaction is really a friendly process for environment, ecotoxicity test on leachates were done, results confirming their non toxic content.
All tests were carried out on a large selection of treatment conditions (temperature and duration) according to two different processes; in total 30 cases applied on Spruce, Poplar and Curupixa; additionnal scots Pine cases were also tested.
The results of all tests have permitted to select 3 cases of conditions, owing to the adequate temperature is about 230 C. For less temperatures, durability is not sufficient and for higher temperatures, integrity of mechanical properties is not respected.
A window manufacture was done on line in two window plants. Some problems arose concerning tooling, fasteners setting, indicating that some changes are needed in particular, new design of profiles are necessary.
By a thermo chemical transformation of wood a material with new properties can be made. Non durable wood species get more hydrophobic properties and become resistant to fungal and insect decay. The mechanical properties and dimensional stability can be maintained or even improved in the torrefaction process. The objective of this project is to study this technology in relation to various potential applications : joinery, waterworks, hardwood replacement, etc. ... The wood starting material will be predominantly poplar and spruce as available in the EEC. The torrefaction process aims mainly at up grading these wood species to Hazard Class 3 uses or commodities. The fundamental process parameters
understood as a result of the study (pre competitive part according to CRAFT objectives).
Funding SchemeEAW - Exploratory awards