The influence of curing conditions on properties of melamine modified wood

The curing conditions influence the material properties of wood modified with methylated melamine formaldehyde resin. To identify the most influential parameters, the process conditions were varied separately. The degree of conversion (differential scanning calorimetry; DSC), work in bending, nitrogen fixation, formaldehyde emission, formaldehyde content and content of free formaldehyde were measured to verify the influence of the curing conditions on the material properties. The temperature and duration positively influenced the curing of melamine resin as the DSC results and the nitrogen fixation indicate. However, the relative humidity (RH) had the greatest influence on the material properties: the formaldehyde properties and the work in bending differed most between dry and high RH processes with the latter producing material being less brittle and having lower formaldehyde emissions. It can be derived that DSC measurements, formaldehyde emission and -content are valuable methods to characterize the influence of curing conditions on the material properties. The formaldehyde content in combination with the emission revealed a different formaldehyde release factor for dry and high RH processes. In the future, the curing process conditions can be designed depending on the desired material properties: dry, high temperature processes will lead to more complete curing, whereas hot steam processes can be used for material with low formaldehyde emissions.