4. Conclusions
The results of this research show that all wood vinegars prepared from different resources can be used as coagulating and antifungal agents to replace formic and acetic acids. The coagulating efficiency of all wood vinegars was similar to acetic acid and better than formic acid. The wood vinegars showed higher antifungal efficiency than both formic and acetic acid. The antifungal property of wood vinegars are in order of coconut shell wood vinegar > bamboo wood vinegar > Eucalyptus wood vinegar according to their phenolic compound contents.
Since NR farmers can produce wood vinegar by themselves through charcoal production, it could also reduce the cost of NR sheet's production. Therefore, wood vinegars could become important factors in NR industry with ever rising costs of petrochemical products. This study also provided the first evidence that wood vinegars can inhibit the fungi growth on NR sheets which makes them an environmental friendly substitute for highly toxic antifungal agents.
From our experience with the wood vinegars, our recommendation to NR production is: substitute formic and acetic acids with wood vinegar.
Acknowledgements
This research was supported by the Small Project on Rubber (SPR), National Research Project on Rubber, the Thailand Research Fund and the Center of Excellence for Innovation in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Education, Thailand.