Natural durability of Eucalyptus urophylla plywood treated with NMethylol compound (mDMDHEU) and Cashew Nut Shell Liquid (CNSL)
Keywords:
Blue stain,, Cashew Nut Shell Liquid, Eucalyptus urophylla, modified dimethylol dihydroxyethyleneurea (mDMDHEU), modified plywood, weatherAbstract
Eucalyptus urophylla veneers were impregnated with N-methylol (modified
dimethyloldihydroxy ethyleneurea - mDMDHEU) and Cashew Nut Shell
Liquid (CNSL) following the conditions of vacuum and pressure
impregnation and then heat treated to make modified plywood. The
modified plywood was then exposed to the testing field under natural
weathering conditions of Hanoi, Vietnam for evaluation of the modified
plywood resistance against to weather and microorganism degradation. The
chemical efficiency stability of modified plywood is evaluated basing on
color stability, bonding delamination, blue stain resistance and water uptake
reduction. The results showed a significantly improved color stability E =
12.52 with the plywood treated by mDMDHEU; the plywood treated with
CNSL showed a higher E = 25.48, while the untreated plywood losing
much color by E 37.71. After 9 months of exposures, the mDMDHEU
treated plywood was maintained comparably to the control without
deformation and no bonding delamination (using PRF adhesive) according
to durability level 1 - Very Durable, the delamination of CNSL treated
plywood is at the durability level 2. The bonding delamination of the MUF
plywood treated with mDMDHEU and CNSL passed the level 2 - Durable
The mDMDHEU and CNSL treated plywood are highly resisted to less then
15% blue stain infection. The results after 9 months of ouside weathering
showed low equilibrium moisture content of the mDMDHEU and CNSL
treated plywood at 14,2% và 13,5% respectively as compared to the 25%
moisture content of the untreated plywood.
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