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Juhele interfering with the curing of the resin during the pressing
cycle, which can result in a lower bonding effciency between
wood particles.
The pH of wood varies depending on the species and is
in the range of three to six. The pH of the extractives present
in the wood can inhibit the chemical reactions that harden

the adhesive, thus harming the development of resistance, as
well as the adequate cohesion of the glue line.
It is known that during the production process of OSB
panels, there are occasional material losses in the operational
phase of mat formation, causing the effective density of the
panels to be lower than the nominal density.
In order to avoid the material losses problem during the
consisted of fve types of OSB with three replications, totalling production process, in the calculation for the manufacture of
15 panels with different proportions of strands per species. the panels assessed in this study, 10 percent extra material

In all panels, pine strands had some percentages in the was added, which is why the effective density of the panels
composition of the OSB panels. To compare the different produced in this study was higher than the planned nominal
mixtures, an analysis of variance was performed, and Tukey’s density of 650 kg/cubic metres.
mean test, at a fve percent error probability level. Panels with an apparent density of 590 to 800 kg/cubic
The statistical software used for data analysis was R metres are classifed as medium-density panels. Thus, all the
software version 4.2.2. The average values of each evaluated panels obtained in this study ft the classifcation mentioned
property, per panel category, were obtained and then compared by the referred authors.

with the minimum values specifed by the EN 300 standard. The panel compression rate was greater than 1.3. A
wooden panel compaction ratio must be at least 1.3 for the
Extractive Content, Physical & Mechanical Properties necessary mat densifcation to occur, providing adequate
Regarding the percentage of total extractives, it appears that contact between strands, so that there is good bonding and
the species that presented the highest extractive content was proper consolidation of the panel during the hot-pressing phase.
Caryocar villosum, followed by Hymenolobium excelsum and The 100 percent pine (T1) showed the highest water
Erisma uncinatum. absorption at 2 and 24 h. In addition to the species factor,
According to Frihart and Hunt, higher-density woods have another component that may have infuenced this result is
a higher concentration of extractives, which can interfere the difference between the basic density of pine wood and

with the curing of adhesives. As reported by Iwakiri, the the densities of wood mixtures.
concentration of extractives in the surface layers of wood Lower-density woods, due to their greater porosity,
can block the passage of water and delay its evaporation absorb a greater amount of water compared to high-density
rate, increasing pressing time. woods. Particleboards with wood residue mixtures from
Wood species with a low extractive content are preferable, fve tropical species (Hymenolobium sp./Andira sp., Qualea
as wood with a high extractive content is more susceptible sp., Nectandra sp./Ocotea sp., Cedrelinga cateniformis, and
to generating problems, such as, for example, negatively Mezilaurus itaúba), showed lower water absorption values