able 2. The difference between each system on formaldehyde emission was not shown in FLEC data while TVOC of tannin/PVAc hybrid adhesives were slightly increased compare to the natural tannin adhesive.
3.3. Curing behavior
It is important to understand the thermal properties because tannin adhesives are thermosetting adhesives. These resins are in the liquid state at room temperature and become solid at high temperature after curing has taken place. Dynamic thermal mechanical test methods have been widely used for investigating the structures and dynamic mechanical properties of thermoset
Table 2 Formaldehyde and TVOC emission of engineered flooring bonded with Natural adhesive and tannin/PVAc hybrid adhesives by desiccator and FLEC method Equipment Desiccator (mg/L) FLEC (mg/m2 h) Air pollutant Formaldehyde Formaldehyde TVOC Non-coated Coateda Natural tannin adhesive 1.19 0.34 0.2 0.32 Tannin90/PVAc10 1.32 0.44 0.21 0.39 Tannin80/PVAc20 1.33 0.47 0.21 0.4 a UV curable urethane acrylate coating.
50
100
150
200
Tannin adhesive Tannin90/PVAc10 Tannin80/PVAc20
0
50
100
150 Emission concentration (μg/ m3)
Adhesives for surface bonding
Toluene TVOC Ethybenzene Styrene Xylene
TVOC Emission concentration (μg/m3)
Fig. 2. VOC emission concentrations (toluene, ethylbenzene, xylene and styrene) from engineered flooring bonded with natural adhesive and tannin/PVAc hybrid adhesives as determined by