Test for Measuring Formaldehyde Emission from Formaldehyde Resin Bonded Particleboards and Plywood

The amount of free formaldehyde in particleboard and plywood was quantitatively determined by heating, under vacuum, a sample of ground board and absorbing the liberated in formaldehyde in water. The amount of formaldehyde collected was determined by titration. The board samples were from various sources with some being made under carefully controlled conditions. Three main factors affect the amount of free formaldehyde. These are moisture content, resin composition, and temperature. By increasing the moisture content four fold (2-1/2 percent to 10 percent), the free formaldehyde is increased over six fold. The manufacture of a special low free formaldehyde resin can decrease the free formaldehyde by a factor of three over boards made with conventional resins. The square of the free formaldehyde varies linearly with the temperature of the board. The free formaldehyde varies linearly with the resin content of the board, while press time affects free formaldehyde only slightly. The temperature and moisture have large effects because the breakdown of urea-formaldehyde resins is hydrolytic in nature.

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