The effects of several parameters on the storage stability of the melamine-formaldehyde (MF) polymers by using a traditional design of experiment (DOE) software

Melamine-formaldehyde (MF) polymer is a hard, thermosetting plastic material made from melamine and formaldehyde by polymerization. The limited storage stability of MF polymer solutions hampers the applicability of these resins. The effects of several operative parameters, viz., reaction vessel pH, reaction time and temperature on the synthesized polymers (resins) stability time were investigated. The results were supported by FTIR, DSC and TGA identification techniques. A design of experiment (DOE) software was employed to derive an appropriate equation to predict the stability time of the synthesized MF polymer and also, to derive the optimum values of the studied parameters. The experimental tests showed that the studied parameters were effective on the stability of the MF. The original MF polymer solutions had less stability than water-diluted polymer solutions. The FTIR spectrums proved the bridge formation between two methylol-melamines and consequently, MF polymer synthesis. The DOE software suggested a second-order polynomial equation to predict the stability time of the MF polymers. The software also suggested the optimum parameters’ values of 8.47, 1.87 h and 71.36 °C for the reaction vessel pH, reaction time and temperature, respectively. By using the aforementioned optimum values, the stability time was calculated as 22.44 days.